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Differences between Casting Vs. Forging

Steel items can be produced through either casting or forging processes. In steel casting, the metal is melted until it becomes liquid and is then poured into a mold to form the desired shape. Conversely, steel forging involves applying mechanical pressure to heated solid steel blocks (like ingots or billets), and permanently molding them into the required products.

STEEL FORGING VS. CASTING

BASIC DEFINITIONS

Steel casting and forging are two fundamental manufacturing processes used to form steel into desired products, each with distinct characteristics, advantages, and applications. Understanding the differences between these methods is crucial for choosing the most suitable approach for specific industrial needs.

Steel Casting

Steel casting involves melting steel into a liquid state and pouring it into a mold, where it solidifies into a specific shape. This process is advantageous for creating complex shapes and components that would be challenging to manufacture through other methods. Cast steel products can range from simple parts like gears and valves to intricate designs such as components for heavy machinery and automotive assemblies.

Steel casting finds applications in industries where complex shapes or specialized materials are required, including automotive, mining, aerospace, and construction.

Steel Forging

Forging involves heating solid steel blocks (ingots or billets) and then deforming them under high pressure or impact to achieve the desired shape. This process can be performed at various temperatures, leading to classifications such as cold forging, warm forging, and hot forging.

Steel forging is widely used in industries requiring high-strength components, such as automotive and aerospace for parts like gears, shafts, levers, and critical fasteners (including valves).

Cast Valve Materials

Both manufacturing processes require the application of high temperatures to steel raw materials (to liquefy or make it malleable) and the execution of CNC machining work at the end of the process to obtain the final product.

Final products may also undergo surface finish treatment, such as painting, powder coating, polishing, various types of coating (for example zinc plating) and wear protection/hardening (application of tungsten carbide overlay).

Last but not least, cast and forged parts may be assembled, welded, brazed, and hard-faced before being shipped as final products.

The products resulting from casting and forging processes have different properties in terms of surface porosity (generally better for forged vs. cast products), grain structure (finer for forged products), tensile strength (generally superior for forged products), and fatigue resistance.

These alternative manufacturing processes are therefore used (and suited for) different circumstances and applications.

CHOOSING BETWEEN CAST & FORGED PRODUCTS

The decision to use casting or forging depends on several factors:

  • Design Complexity: Casting is preferred for more complex shapes while forging is ideal for simpler, high-strength parts.
  • Material Properties: If the application requires specific alloy properties, casting may offer more flexibility. For applications where material strength and integrity are paramount, forging is often the better choice.
  • Production Volume: Forging can be more cost effective for large production runs of simpler shapes, whereas casting can be more economical for small to medium batches, especially of complex parts.
  • Cost Considerations: Initial setup costs for casting molds can be high, but per-unit costs decrease with volume. Forging requires significant investment in tooling and machinery, especially for high-volume production.

The casting process is generally preferred for:

  • parts and components that would be too complex or expensive to manufacture by steel forging (for example: large valve bodies);
  • parts that have internal cavities;
  • large-sized parts (there are virtually no size limits in terms of the weight of the parts that can be produced with the casting process);
  • parts in special alloys (some specific alloys are more difficult to forge than cast, for example, those with a high content of Nickel and Moly, which have considerable resistance to mechanical forces);
  • parts requiring mass production and small lots.

The forging process is preferred for:

  • parts requiring extremely high strength, toughness, and resistance (indeed, during the forging process the steel grain structure gets modified to conform to the shape of the final product – with high uniformity of composition and metallurgical recrystallization);
  • parts that have to withstand stronger impacts and mechanical forces;
  • parts where porosity, the risk of a gas void, pockets, and the possible formation of cavities (even micro-granular) are not acceptable;
  • production of mechanically strong parts without using expensive alloys;
  • parts that require high wear resistance;
  • parts subject to high loads and stress;
  • high-end applications when the integrity and the quality of the part are the main objectives in the production process, rather than time and cost.

 

The evolution of casting technologies has reduced the gap between the physical properties of cast vs. forged products making modern cast products very competitive in terms of quality, strength, and wear resistance: however, in many fields, steel forging remains, still, the preferred manufacturing option (example: small sized valves, i.e. forged valves, or high-pressure valves).

Read about forging steel on Wikipedia.

FIELDS OF APPLICATION

Steel casting and forging are used to produce products and parts for a multitude of sectors, including but not limited to:

  • petrochemical plants (for example forged valves, forged fittings, flanges, etc)
  • power generation and waste processing
  • mining and mineral processing
  • agriculture and livestock handling
  • water treatment
  • aeronautics
  • automobile industry (pulleys and gear wheels)
  • materials handling
  • brickworks
  • asphalt plants
  • stormwater parts
  • rendering plants
  • railways

STEEL CASTING

DEFINITION

Steel casting is a manufacturing process that involves melting steel until it becomes liquid, then pouring the molten steel into a mold where it solidifies into the desired shape. This method allows for the production of parts with complex geometries and detailed features that might be challenging to achieve through other manufacturing processes.

cast valve body
cast valve body

The molds used can be made from a variety of materials, including sand, metal, or ceramics, depending on the precision, surface finish, and reuse requirements of the casting. Steel castings are utilized across a broad range of industries, including automotive, aerospace, construction, and energy, due to their versatility in shape and size, and the ability to tailor the material properties through the selection of specific steel alloys and post-casting treatments such as heat treatment.

This process is particularly valuable for producing components that require high strength, durability, and resistance to wear and corrosion.

STEEL CASTING PROCESS

The steel casting manufacturing process involves several key steps that transform steel into precisely shaped components. This process is known for its ability to produce complex shapes and sizes, offering flexibility in design and material properties.

Here’s an overview of the main stages in the steel casting manufacturing process (in general terms, variations may exist based on the specific type of casting process adopted):

1. Pattern Making

The first step is creating a pattern that represents the shape of the final casting. Patterns can be made from various materials such as wood, plastic, or metal, depending on the complexity of the design and the casting quantity. The pattern is a replica of the final part but slightly larger to account for the shrinkage of the metal during cooling.

2. Mold Making

Using the pattern, a mold is made by packing a molding material (often sand mixed with binders) around the pattern in a molding box. When the pattern is removed, it leaves a cavity in the shape of the part to be cast. For complex parts, the mold consists of two halves (cope and drag) that are assembled before pouring. Cores may be used to form internal cavities within the casting.

3. Melting and Pouring

Steel is melted in a furnace at temperatures exceeding 1600°C (2900°F). The composition of the steel alloy is carefully controlled to meet the specific properties required for the casting. Once the steel is melted and any required alloying elements are added, the molten steel is poured into the prepared mold. The pouring process must be carefully controlled to ensure the mold is filled completely and to avoid defects.

4. Solidification and Cooling

After pouring, the steel begins to cool and solidify within the mold. Cooling rates can affect the microstructure and properties of the cast part. In some cases, directional solidification is used to control the way the metal cools, minimizing internal stresses and defects.

5. Mold Removal

Once the steel has fully solidified and cooled, the mold material is broken away to reveal the cast part. Sand molds are typically destroyed to remove the casting, while metal molds (used in permanent mold casting processes) are opened and reused.

6. Cleaning and Finishing

The casting is cleaned to remove any residual mold material and inspected for defects. Excess material from the pouring process, such as gates and runners, is removed. The casting may undergo various finishing processes, including grinding, machining, and heat treatment, to achieve the desired surface finish and mechanical properties.

7. Inspection and Quality Control

The final step involves inspecting the casting for defects and ensuring it meets the specified dimensions and material properties. Non-destructive testing methods such as X-ray or ultrasonic testing may be used to detect internal defects.

ADVANTAGES/DISADVANTAGES OF CAST STEEL

Advantages

Cast steel offers a unique set of advantages that make it a preferred choice for a wide range of applications across various industries. These benefits stem from the versatility of the casting process as well as the intrinsic properties of steel. Here are some of the key advantages of cast steel:

1. Design Flexibility

Cast steel allows for the production of complex shapes and intricate designs that are difficult or impossible to achieve with other manufacturing processes. This flexibility enables designers and engineers to create components with optimized geometries for specific applications, incorporating features like internal cavities, contours, and complex external shapes without the need for assembly or welding of multiple parts.

2. Material Properties

Steel casting can utilize a wide range of steel alloys, offering the ability to tailor the material properties to specific application requirements. This includes adjusting the alloy composition to enhance strength, ductility, wear resistance, impact resistance, and corrosion resistance. Additionally, post-casting heat treatments can further modify the mechanical properties, providing additional customization options to meet the demands of the application.

3. Large Component Production

The steel casting process is well-suited for producing large components that would be challenging or cost-prohibitive to manufacture through forging or machining from a solid block of steel. This capability is particularly valuable in industries such as mining, construction, maritime, and energy, where large, durable components are essential.

4. Cost-Effectiveness

For small to medium production volumes, casting can be more cost-effective than other manufacturing methods, especially for complex shapes that would require extensive machining or assembly of multiple parts. The ability to produce near-net-shape components reduces the need for additional processing and material waste, further contributing to cost savings.

5. Surface Finish and Detail

Cast steel can achieve a good surface finish and a high level of detail directly from the mold, reducing the need for additional finishing processes. This is beneficial for parts that require precise dimensions or aesthetic considerations.

6. Reliability

Steel castings undergo stringent quality control and testing procedures to ensure they meet the required specifications and standards. Non-destructive testing (NDT) techniques, such as x-ray, ultrasonic, and magnetic particle inspection, help detect any internal or surface defects, ensuring the reliability and performance of the cast component in its intended application.

7. Speed to Market

The casting process can be relatively quick from design to production, especially for prototypes or limited production runs. This speed can significantly reduce the time to market for new products or components, providing a competitive advantage.

In conclusion, the combination of design flexibility, customizable material properties, and cost-effectiveness makes cast steel a versatile and valuable option for a wide range of industrial applications. From heavy machinery and automotive components to artistic and architectural elements, the advantages of cast steel enable engineers and designers to meet complex challenges and deliver innovative solutions.

Disadvantages

The manufacturing and utilization of cast steel components offer distinct advantages but also come with certain disadvantages. Understanding these can help in making informed decisions about when and how to use cast steel in various applications:

1. Cost

  • Initial Costs: The production of cast steel components can involve high initial costs due to the need for specialized molds, which can be expensive to manufacture, especially for intricate designs or low production volumes. This can make cast steel less economical for small batches.
  • Material Costs: Steel, especially alloyed varieties used in casting for enhanced properties, can be more expensive than other metals, adding to the overall cost of the casting process.

2. Surface Finish and Tolerances

  • Surface Finish: Cast steel might have a rougher surface finish compared to other manufacturing processes like forging or machining. This can necessitate additional finishing processes, increasing production time and costs.
  • Dimensional Tolerances: Achieving tight dimensional tolerances can be more challenging with cast steel, especially for complex shapes or large components. This might require further machining or processing to meet precise specifications.

3. Porosity and Defects

  • Porosity: The casting process can introduce porosity (tiny holes or voids) in the steel, which can affect the mechanical strength and integrity of the part. Porosity is particularly concerning in applications where pressure integrity or structural strength is critical.
  • Defects: Castings are susceptible to various defects such as shrinkage cavities, cold shuts, and inclusions. These defects not only compromise the structural integrity and mechanical properties of the part but also require rigorous inspection and quality control measures to detect and mitigate.

4. Material Limitations

  • Alloy Restrictions: While casting allows for the use of a wide range of alloys, some compositions might not be suitable for casting due to their melting characteristics or reactions with mold materials. This can limit the choice of materials for specific applications.
  • Size and Weight Limitations: There are practical limits to the size and weight of cast steel components, dictated by the capacity of foundry equipment and the challenges of managing heat dissipation and material properties uniformly across large castings.

5. Environmental Considerations

  • Energy Consumption: The melting and casting of steel require significant amounts of energy, contributing to the environmental footprint of cast steel products.
  • Waste Production: The process can generate waste, including used molds and cores, excess metal from gates and risers, and defective castings, which need to be managed and recycled when possible.

TYPES OF STEEL CASTING PROCESSES

Steel casting processes can be categorized based on the type of mold used, the method of mold filling, and the handling of the molten steel. Each process has its unique advantages and is suited to specific applications. Here’s an overview of the primary types of steel casting processes:

Sand Casting

Sand casting is the oldest casting method and consists of pouring liquid metal into binders that resist the molten metal (such as clay bonded/green sand hard bonded/resin, thermosetting resin sand, and shell).

Sand Casting

  • Description: This is the most common and versatile method, using sand molds to create steel parts. The sand can be shaped into complex forms, making it suitable for a wide range of components.
  • Applications: Used for large parts and small to medium production runs, including automotive frames, heavy machinery components, and decorative pieces.

Investment Casting (Lost Wax Casting)

This term refers to precision molding executed by injecting the liquid metal into a metal die and a ceramic coating. The mold material can be hard wax, lost wax, lost foam, and similar. Investment casting is the preferred method for manufacturing parts with a high number of details, and small parts that cannot afford the costs of traditional sand casting.

Investment casting process

  • Description: A precision casting process where a wax model is coated with refractory material to create a mold. After the wax is melted out, molten steel is poured into the cavity. This method provides excellent surface finish and dimensional accuracy.
  • Applications: Ideal for small, complex components with tight tolerances, such as turbine blades, medical equipment, and firearm components.

Centrifugal Casting

  • Description: In this process, molten steel is poured into a rotating mold, creating parts with cylindrical shapes. The centrifugal force pushes the molten steel against the mold walls, producing a dense and uniform casting.
  • Applications: Used for components requiring high material integrity, such as pipes, cylinders, and rings.

Continuous Casting

  • Description: A highly efficient process where molten steel is solidified in a continuous strand through a mold. The solidified steel is then cut into desired lengths. This method significantly reduces the need for further processing.
  • Applications: Primarily used for producing basic shapes like billets, blooms, and slabs, which are further processed into various steel products.

Shell Molding

  • Description: Similar to sand casting, but uses a resin-coated sand that bonds to form a shell around the pattern. This method offers a better surface finish and more precise dimensions than traditional sand casting.
  • Applications: Suitable for medium to high-volume production of small to medium-sized parts, such as valve components and gear housings.

Vacuum Casting

  • Description: A process where molten steel is poured into a mold under a vacuum. This reduces the occurrence of defects and improves the quality of the casting by minimizing turbulence and gas entrapment.
  • Applications: Used for components that require high integrity and are free of pores and voids, such as in the aerospace and power generation industries.

Die Casting

  • Note: While die casting is predominantly used with non-ferrous metals due to the high melting point of steel, there are specialized high-pressure die-casting processes capable of handling steel alloys.
  • Applications: Suitable for high-volume production of small, precise components that require a good surface finish.

Each steel casting process has its ideal applications based on the required part size, complexity, production volume, and material properties. Selecting the appropriate casting method is crucial for achieving the desired part performance and cost-efficiency. Sand casting is used for large parts, investment casting for small parts up to 100 kilograms and 1,5 meters of max. length.

STEEL FORGING

DEFINITION

Steel forging is a manufacturing process involving the shaping of metal using localized compressive forces. In steel forging, steel is heated to a high temperature, making it pliable, and then it is hammered, pressed, or rolled into a desired shape.

This process can be performed at various temperatures, leading to different classifications such as hot forging, warm forging, and cold forging, each offering distinct advantages in terms of the material’s ductility and finished properties.

Steel forging appeared in China in the ancient ages to produce various types of metal products.

While the methods and equipment for creating forged components have evolved since those old days—from traditional anvils, hammers, and manual labor to modern automated machinery like hydraulic presses—the fundamental process of steel forging remains consistent. It involves heating solid steel blocks and then shaping them into finished products through the application of mechanical forces, such as hammering.

FORGING PROCESS

The steel forging process is a critical manufacturing technique used to shape metal into desired forms through the application of force and heat. It involves several key steps that transform a piece of steel into a strong, durable component with specific properties. Here’s a detailed look at the steel forging process:

1. Material Selection

The process begins with selecting the appropriate type of steel for the intended application. The choice depends on the required mechanical properties, such as strength, ductility, and resistance to wear and corrosion. Commonly used steel grades in forging include carbon steel, alloy steel, stainless steel, and tool steel.

2. Heating

The selected steel is heated to a high temperature, typically between 950°C and 1250°C (1742°F and 2282°F), although the exact temperature depends on the type of steel and the specific forging process being used. Heating the steel makes it more pliable and easier to deform. This step is crucial for hot forging, while warm forging and cold forging require different temperature ranges.

3. Forging

Once the steel is at the appropriate temperature, it is forged using one of several techniques:

  • Hammer Forging (Drop Forging): The steel is placed on an anvil and struck repeatedly with a hammer, either manually or mechanically. This method is effective for creating a wide variety of shapes with good precision.
  • Press Forging: The steel is compressed between two dies using a hydraulic or mechanical press, applying pressure gradually rather than through successive impacts. Press forging allows for better control over the deformation process and is suitable for large-scale production.
  • Rolled Forging: The heated steel is passed through two rolls that decrease its thickness and increase its length. Rolled forging is commonly used for producing long, cylindrical shapes like shafts.

4. Shaping

During the forging process, the steel’s internal grain structure deforms to conform to the shape of the part. This alignment enhances the mechanical properties of the steel, such as strength and toughness. The steel can be shaped into nearly any form, from simple flat sheets to complex geometrical components.

5. Trimming

Excess material, known as flash, is often produced during the forging process, especially in die forging. This excess material is trimmed off while the steel is still hot or after it cools down, depending on the specific process and material properties required.

6. Heat Treatment

After forging, the steel components may undergo various heat treatment processes such as annealing, normalizing, quenching, and tempering. These treatments are used to adjust the steel’s properties, such as increasing hardness, improving ductility, or relieving internal stresses induced during forging.

7. Finishing

The last step involves finishing the forged steel component to achieve the desired surface finish and dimensional accuracy. This may include machining, grinding, and polishing, depending on the application requirements.

8. Inspection and Testing

Finally, the forged steel components are inspected and tested to ensure they meet the required specifications and quality standards. This can involve dimensional checks, visual inspection, and various non-destructive testing methods, such as ultrasonic or magnetic particle inspection.

Upon completion of the process, the resulting products possess remarkable strength, impact toughness, and resistance to wear. This is attributed to the metallurgical changes, specifically recrystallization and grain refinement, that occur due to the thermal and mechanical treatments applied during the process.

The video below shows how steel forging works:

ADVANTAGES/DISADVANTAGES OF FORGED STEEL

Forged steel, known for its strength and reliability, is a preferred material for many industrial applications. However, like any manufacturing process, steel forging has its set of advantages and disadvantages. Understanding these can help in making informed decisions about its use in specific applications.

Advantages Of Forged Steel

1. Superior Strength and Toughness

Forging refines the grain structure of the steel, aligning it with the shape of the product. This enhances the mechanical properties of the steel, making forged parts stronger and more resistant to impact and fatigue compared to cast or machined parts.

2. Improved Reliability

The forging process produces parts with consistent material properties and without internal voids, cracks, or other defects that could weaken the part. This uniformity ensures high reliability and performance, especially in critical applications.

3. Reduced Material Waste

Modern forging techniques are highly efficient, often resulting in less material waste compared to other manufacturing processes like casting or machining. This efficiency can lead to cost savings, especially in high-volume production.

4. Versatility in Materials

Steel forging can be performed with a wide range of alloys, allowing for the production of parts with specific properties tailored to the application, including high-temperature resistance, corrosion resistance, and wear resistance.

5. Cost-Effective for Large Production Runs

Although the initial setup and tooling costs can be high, forging can be more cost-effective than other processes for large production runs due to its material efficiency and the reduced need for secondary processing.

Disadvantages Of Forged Steel

1. Higher Initial Costs

The initial costs for setup and tooling in forging can be significant, especially for complex shapes. This can make forging less economical for small production runs compared to other manufacturing processes.

2. Limitations on Shape Complexity

While forging can produce a wide range of shapes, extremely complex or intricate designs may be challenging to achieve through forging alone and might require additional machining or processing.

3. Size Limitations

The size of forgings is generally limited by the capacity of the forging equipment. Very large components might be difficult or impractical to forge and may require alternative manufacturing methods.

4. Need for Secondary Processing

Depending on the application’s requirements, forged parts may require secondary processes such as machining, heat treatment, or surface finishing to achieve the desired dimensions, properties, or surface quality.

5. Energy Intensive

The forging process, particularly hot forging, requires significant amounts of energy to heat the metal, which can impact the overall environmental footprint of the manufacturing process

TYPES OF STEEL FORGING PROCESSES

Steel forging processes vary in technique and application, each suited to different manufacturing requirements and objectives. These processes are categorized mainly based on the temperature at which the steel is forged (cold, warm, or hot forging) and the method of applying force (hammer or press forging). Here’s a closer look at the primary types of steel forging processes:

1. Hot Forging

  • Description: Performed at temperatures typically between 950°C and 1250°C (1742°F to 2282°F), hot forging allows the steel to be shaped easily, as the high temperature increases its plasticity and reduces resistance to deformation.
  • Advantages: Enables the forging of complex shapes with less force and energy; reduces strain hardening during the process.
  • Applications: Used for parts that require high strength and toughness, such as automotive components, construction equipment, and machinery parts.

2. Cold Forging

  • Description: This process is carried out at or near room temperature, offering a cleaner finish and stronger products due to strain hardening.
  • Advantages: Produces parts with excellent surface finish and dimensional accuracy; increases the strength of the steel through work hardening.
  • Applications: Suitable for smaller products with simpler shapes, like fasteners, screws, and bolts, where high precision and strength are required.

3. Warm Forging

  • Description: Warm forging is conducted at temperatures ranging from 650°C to 950°C (1202°F to 1742°F), serving as a middle ground between hot and cold forging.
  • Advantages: Balances the benefits of hot and cold forging, allowing for reduced force compared to cold forging and better dimensional accuracy than hot forging.
  • Applications: Often used for medium-complexity parts where a balance between strength, precision, and cost is needed.

4. Open-Die Forging

  • Description: In open-die forging, the steel is worked between two flat or simply contoured dies that do not enclose the workpiece, allowing the material to flow outward as it is forged.
  • Advantages: Highly versatile, capable of producing very large parts, and allows for the adjustment of the workpiece during forging.
  • Applications: Ideal for large, simple shapes such as shafts, bars, beams, and plates.

Open die forging involves shaping metal by pressing or hammering it between two dies that don’t entirely enclose the material. The piece of metal is worked upon through successive movements of the dies, which apply force to mold the metal into the desired shape. This technique is demonstrated in the action showcased in the video below:

5. Closed-Die Forging (Impression-Die Forging)

  • Description: Steel is compressed between two or more dies that contain a precut profile of the desired part, resulting in a more precise and complex shape.
  • Advantages: Produces parts with close tolerances and minimal waste; suitable for high-volume production.
  • Applications: Widely used for automotive, aerospace, and industrial components that require detailed features and high strength.

Closed-die forging is a process where the dies close in on the workpiece, either completely enclosing it or partially. The process begins by placing a piece of heated raw material, roughly shaped or sized to match the final product, into the lower die. This process is demonstrated in the following video:

6. Seamless Rolled Ring Forging

  • Description: This process involves piercing a hole in a thick, round piece of metal to create a donut shape, which is then rolled and stretched to produce a seamless ring.
  • Advantages: Efficiently produces rings with excellent structural integrity and homogeneous characteristics.
  • Applications: Commonly used for bearings, flanges, gear rings, and wind turbine components.

Difference Between Open-Die & Close-Die Forging

Open-die and closed-die forging are two fundamental processes used in metalworking to shape metal, especially steel, into desired forms through the application of force. While both processes serve the purpose of forging, they differ significantly in their methodologies, applications, and the types of products they produce. Understanding these differences is crucial for selecting the appropriate forging process for a specific application.

Open-Die Forging Key Features
  • Versatility in Shape and Size: Suitable for large or uniquely shaped components that cannot be forged in closed dies.
  • Flexibility in Production: Ideal for low-volume production or one-off items due to the adaptability of the process.
  • Less Precise Dimensions: The final products may require further machining to achieve the desired dimensions and tolerances.
  • Greater Material Handling: Larger workpieces can be accommodated, which is beneficial for creating large industrial components.
Open-Die Forging Applications

Large industrial parts like shafts, beams, and simple shapes that require significant material deformation but not intricate details or precise dimensions.

Close-Die Forging Key Features
  • High Precision and Detail: Produces parts with close tolerances and complex geometries without the need for significant post-forging machining.
  • Efficiency in High-Volume Production: More suitable for mass production of parts due to the repeatability and speed of the process.
  • Limited to Smaller Sizes: Generally used for smaller components due to the constraints of the die sizes and press capacities.
  • Reduced Material Waste: The process is designed to closely approximate the final part shape, minimizing excess material.
Close-Die Forging Applications

Automotive, aerospace, and hardware components that require precise dimensions, complex shapes, and high strength, such as gears, levers, and fasteners.

Conclusion

The choice between open-die and closed-die forging depends on the specific requirements of the project, including the size and complexity of the parts, the precision needed, the volume of production, and cost considerations. Open-die forging is favored for its flexibility and capability to produce large parts, whereas closed-die forging is preferred for its efficiency and ability to produce parts with complex shapes and tight tolerances.

OPen vs Closed Die Forging Steel

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HOW TO ORDER A VALVE

Learn about the different types of valves used in the oil and gas industry: API and ASME gate, globe, check, ball, and butterfly designs (manual or actuated, with forged and cast bodies). Valves are mechanical devices used in piping applications to control, regulate and open/close the fluid’ s flow and pressure. Forged valves are used for small bore or high-pressure piping applications, cast valves for piping systems above 2 inches. 

WHAT ARE VALVES?

INTRODUCTION TO OIL & GAS VALVES

Valves play a crucial role in the oil and gas industry, serving as the gatekeepers for controlling the flow of fluids through pipelines and equipment. These mechanical devices can open, close, or partially obstruct pathways to manage the movement of oil, gas, and sometimes water or other fluids, ensuring safe and efficient operation of extraction, processing, transportation, and storage systems.

Petrochemical valves
Petrochemical Valves

Let’s delve into the importance, types, and applications of valves in the oil and gas sector, offering a comprehensive overview for readers interested in the pivotal role these components play in our energy infrastructure.

Functions Of Valves In Oil And Gas

Valves are indispensable for the oil and gas industry due to their ability to:

  • Control the Flow: Regulate the rate of flow of oil and gas in pipelines, ensuring optimal operation conditions (start/stop/modulate/change the direction of the flow)
  • Maintain the Pressure: Keep the pressure within pipelines and systems at safe levels to prevent accidents and ensure the integrity of the system.
  • Ensure Safety: Act as safety devices that can shut off flow in emergency situations, preventing leaks, spills, and catastrophic failures.
  • Allow operational Flexibility: Allow for the maintenance of parts of the system without shutting down the entire operation, providing operational flexibility and minimizing downtime.

Petrochemical valves

(Source: Spirax Sarco)

ypes Of Valves In Oil And Gas

The oil and gas industry uses a wide variety of valves, each designed for specific functions, pressure ranges, and fluid types. Some of the most common include:

  • Gate Valves: Used for on/off control of fluid flow, offering minimal restriction when fully open.
  • Globe Valves: Ideal for regulating flow or pressures as well as starting or stopping flow due to their precise throttling capabilities.
  • Ball Valves: Known for their quick shut-off capabilities, providing a tight seal with a quarter-turn motion, suitable for both on/off and throttling services.
  • Butterfly Valves: Feature a disc that rotates to open or close the flow path. They are compact and suitable for large-diameter pipes, offering quick operation and low-pressure drop.
  • Check Valves: Allow fluid to flow in one direction only, preventing backflow that could damage equipment or disrupt the process.
  • Safety Valves: Automatically release pressure when it exceeds set limits to protect equipment and ensure safe operations.
  • To explore these valve types in greater detail, our site hosts specialized articles for each category. Follow the links mentioned above to gain a more comprehensive understanding of each specific valve type, if you wish to broaden your expertise.

    Applications Of Valves In Oil And Gas

    Valves are used throughout the oil and gas supply chain, from upstream exploration and production to downstream refining, distribution, and storage:

    • Upstream Operations: In drilling rigs, production wells, and offshore platforms, valves control the flow of oil and gas from reservoirs to the surface and manage injection processes for enhanced recovery.
    • Midstream Infrastructure: Valves are used in pipelines, pumping stations, and compressor stations to transport oil and gas across long distances, ensuring that flow and pressure levels are maintained.
    • Downstream Processing: In refineries and petrochemical plants, valves manage the flow of crude oil into various processes for separation, conversion, and treatment to produce fuels and chemicals.
    • Storage and Distribution: Valves are essential in tank farms and terminals for controlling the storage and loading of oil, gas, and finished products for distribution.

    A valve is manufactured by assembling multiple mechanical parts, the key ones being the body (the outer shell), the trim (the combination of the replaceable wetted parts), the stem, the bonnet, and an actioning mechanism (manual lever, gear, or actuator).

    Valves with small bore sizes (generally 2 inches) or that require high resistance to pressure and temperature are manufactured with forged steel bodies; commercial valves above 2 inches in diameter feature cast body materials.

    The valve market is rather huge in terms of revenues and number of dedicated workers: it was worth approximately 40 billion USD per year in 2018. The major manufacturers of oil & gas valves are located in the US, Europe (Italy, Germany, France, and Spain), Japan, South Korea, and China.

    In conclusion, valves are fundamental to the safe, efficient, and effective operation of the oil and gas industry, ensuring that energy resources are extracted, processed, transported, and stored with precision and care. Their variety and adaptability make them indispensable tools in the complex systems that fuel the modern world.

  • VALVE TYPES

    Valves used in the oil and gas industry and for piping applications can be classified in multiple ways:

    BY DISC TYPE (LINEAR, ROTARY, QUARTER TURN)

    In the diverse world of valves, categorizing them by their operational mechanics—specifically, how they move to regulate flow via the disc —provides insight into their suitability for different applications in industries like oil and gas, water treatment, and chemical processing.

    Let’s explore the distinctions between linear motion valves, rotary motion valves, and quarter-turn valves to understand their functionalities, advantages, and typical uses.

    Linear Motion Valves

    Linear motion valves operate by moving a closure element in a straight line to control the flow of fluid. This category includes:

    • Gate Valves: Utilize a flat gate that moves vertically to the flow, providing a straight-through pathway when open and a secure seal when closed.
    • Globe Valves: Feature a plug that moves up and down against the flow, offering precise flow regulation and the capability to stop flow entirely.
    • Diaphragm Valves: Employ a flexible diaphragm that moves up and down to permit or restrict flow.

    Advantages:

    • Precise control of flow and pressure.
    • Suitable for on/off and throttling applications, particularly where flow rate control is essential.

    Typical Uses:
    Situations requiring tight shut-offs and flow regulation, such as in water treatment plants and in the control of gas or steam.

    Rotary Motion Valves

    Rotary motion valves rotate a disc or ellipse about an axis to control fluid flow. This group encompasses:

    • Ball Valves: Contain a ball with a hole through it, which rotates 90 degrees to open or close the flow path.
    • Butterfly Valves: Have a disc mounted on a rod, which rotates to allow or block flow.

    Advantages:

    • Compact and lightweight design.
    • Quick operation with low torque requirements.
    • Generally lower in cost than linear motion valves for the same size and rating.

    Typical Uses:
    Broadly used in applications requiring rapid operation and space-saving solutions, such as in the chemical industry and for water distribution systems.

    Quarter-Turn Valves

    Quarter-turn valves are a subset of rotary motion valves that operate with a simple 90-degree turn of the handle or actuator to go from fully open to fully closed positions, or vice versa. This category includes Ball Valves and Butterfly Valves, as mentioned above, due to their quarter-turn operation.

    Advantages:

    • Speed and ease of operation.
    • Effective shut-off capabilities, making them ideal for both isolating and control applications.
    • Versatility in handling a wide range of media, pressures, and temperatures.

    Typical Uses:
    Extensively used across various sectors, including oil and gas for pipeline flow control, in manufacturing processes, and in HVAC systems for controlling water flow and temperature.

    In summary, the choice between linear motion, rotary motion, and quarter-turn valves depends on specific application requirements such as the need for precise flow control, space constraints, and operational efficiency. Linear motion valves excel in providing precise control and tight shut-off, rotary motion valves offer compact and quick solutions, and quarter-turn valves bring the best of rotary action in terms of speed and simplicity, making them versatile for a wide array of applications.

  • Oil & Gas Valve Types Linear motion valves Rotary  motion valves Quarter turn valves
    Gate valve X
    Globe valve X
    Check valve X
    Lift check valve X
    Tilting-disc check valve X
    Stop check valve X X
    Ball valve X X
    Pinch valve X
    Butterfly valve X X
    Plug valve X X
    Diaphragm valve X
    Safety Valve / Pressure Relief Valve X

  • VALVES BY BODY MATERIAL (CAST, FORGED)

    The distinction between cast and forged valves lies in their manufacturing processes, which fundamentally affect their physical characteristics, performance, and applications.

    As a general rule, cast bodies are used for valves above 2 inches in bore size, whereas forged bodies are used for valves below 2 inches (or preferred to cast valves, regardless of the pipeline bore size, in mission-critical applications). 

    Both types of valves play critical roles in controlling the flow of liquids and gases in various industries, including oil and gas, power generation, and water treatment.

    Understanding the differences between cast and forged valves is essential for selecting the right valve for a specific application, ensuring optimal performance, durability, and safety.

    Cast Valves

    Manufacturing Process

    Cast valves are made by pouring molten metal into pre-shaped molds where it solidifies into the desired valve shape. The casting process can be done through various methods, including sand casting, investment casting, and die casting, each with its own set of characteristics regarding surface finish, dimensional accuracy, and intricacies of design.

    Characteristics

    • Versatility in Design: Casting allows for complex shapes and sizes, making it possible to produce valves with intricate internal geometries that would be difficult or impossible to achieve through forging.
    • Material Variety: A wide range of materials can be cast, including various types of steel, iron, and non-ferrous alloys, offering flexibility in material selection based on the application requirements.
    • Cost-Effectiveness for Complex Shapes: For complex shapes and larger sizes, casting can be more cost-effective than forging, especially for low to medium-volume production.

    Limitations

    • Potential for Defects: The casting process can introduce internal defects such as porosity, shrinkage cavities, and inclusions, which can affect the mechanical properties and integrity of the valve.
    • Variability in Quality: Cast valves can exhibit variability in quality and material properties across different batches due to the nature of the casting process.
    Forged Valves

    Manufacturing Process:
    Forged valves are created through the process of forging, where a piece of metal is heated and then deformed and shaped into the desired form using high pressure. Forging can be performed using various techniques, including open-die forging, closed-die forging, and ring rolling, depending on the desired final shape and characteristics.

    Characteristics

    • Strength and Durability: Forging produces valves with superior strength, ductility, and resistance to impact and fatigue compared to casting. The forging process aligns the grain structure of the metal with the shape of the valve, enhancing its mechanical properties.
    • Consistency in Quality: Forged valves generally offer more uniformity and consistency in material properties, with fewer internal defects than cast valves.
    • High Performance in Critical Applications: Due to their strength and reliability, forged valves are preferred in high-pressure, high-temperature, and other critical applications where safety and performance are paramount.

    Limitations

    • Design Limitations: Forging cannot achieve the same level of complexity and intricate internal features that casting can, especially for large or very complex valve designs.
    • Cost Considerations: For high-volume production of simple shapes, forging can be cost-effective. However, for complex shapes or lower volumes, the cost may be higher than casting, particularly for large-sized valves.

    In summary, the choice between cast and forged valves depends on the specific requirements of the application, including mechanical strength, pressure and temperature conditions, desired material properties, design complexity, and cost considerations. Forged valves are typically favored in high-stress, high-performance applications due to their superior strength and reliability, while cast valves offer greater design flexibility and cost-effectiveness for complex shapes and large sizes.

  • To learn more about the difference between steel casting and forging please refer to the linked article.

    VALVES BY TYPE OF ACTUATION (MANUAL, ACTUATED)

    Valves can also be categorized based on their method of operation into manually operated valves and actuated valves. Understanding the differences between these two types is crucial for selecting the appropriate valve for a specific application, considering factors like ease of operation, control precision, and the necessity for automation.

    Manually Operated Valves

    Characteristics

    • Operation: Manually operated valves require physical effort by an operator to change their position, using handwheels, levers, or gears. The manual input directly controls the opening, closing, or throttling of the valve.
    • Design Simplicity: These valves are simpler in design as they do not require additional equipment for operation, making them straightforward to install and maintain.
    • Cost-effectiveness: Without the need for external power sources or automation equipment, manually operated valves are generally more cost-effective than their actuated counterparts.
    • Reliability: With fewer components that could fail, manually operated valves are highly reliable and suitable for applications where valve adjustments are infrequent or where direct manual control is preferred.

    Limitations

    • Labor Intensive: For systems requiring frequent adjustments or in situations where valves are not easily accessible, manual operation can be labor-intensive and time-consuming.
    • Lack of Remote Control: Manual valves cannot be operated remotely, limiting their use in large, complex systems or in hazardous environments where remote operation is necessary for safety.
    Actuated Valves

    Characteristics

    • Operation: Actuated valves are equipped with an actuator that allows valve operation (open, close, or modulate) through electrical, pneumatic, or hydraulic power. Actuators can be controlled remotely, allowing for automation and integration into control systems.
    • Automation and Precision: With the ability to be controlled by various signals (electric, pneumatic, or hydraulic), actuated valves offer precise control over flow and pressure, enabling more efficient operation of the system.
    • Flexibility and Safety: Remote operation capabilities allow actuated valves to be used in inaccessible, hazardous, or harsh environments, improving safety and operational flexibility.
    • Adaptability: They can be integrated into automated control loops, responding to sensor inputs to adjust flow conditions automatically, which is essential for optimizing processes and ensuring safety in dynamic conditions.

    Limitations

    • Complexity and Cost: Actuated valves require additional components (actuators, power sources, control systems) making them more complex and expensive to install and maintain compared to manually operated valves.
    • Power Requirement: Dependence on an external power source (electrical, pneumatic, or hydraulic) for operation can be a limitation in environments where such resources are limited or unavailable.

    In summary, the choice between manually operated and actuated valves depends on several factors, including the need for automation, the operational environment, safety considerations, and cost. Manually operated valves are suitable for simpler, cost-sensitive applications where direct control and infrequent adjustments are sufficient. In contrast, actuated valves are ideal for complex systems requiring precise, remote, or automated control to enhance efficiency, safety, and operational flexibility.

    VALVE BY DESIGN

    Regarding their design, valves can be categorized in the following manner (it’s worth noting that our site features detailed articles on each type, so the descriptions provided here are intended to be broadly overviewed):

    GATE VALVE

    Gate valves are the most used type in piping and pipeline applications. Gate valves are linear motion devices used to open and close the flow of the fluid (shutoff valve). Gate valves cannot be used for throttling applications, i.e. to regulate the flow of the fluid (globe or ball valves should be used in this case). A gate valve is, therefore, either fully opened or closed (by manual wheels, gears, or electric, pneumatic and hydraulic actuators)

    GLOBE VALVE

    Globe valves are used to throttle (regulate) the fluid flow. Globe valves can also shut off the flow, but for this function, gate valves are preferred. A globe valve creates a pressure drop in the pipeline, as the fluid has to pass through a non-linear passageway.

    CHECK VALVE

    Check valves are used to avoid backflow in the piping system or the pipeline that could damage downstream apparatus such as pumps, compressors, etc. When the fluid has enough pressure, it opens the valve; when it comes back (reverse flow) at a design pressure, it closes the valve – preventing unwanted flows.

    BALL VALVE

    A Ball valve is a quarter-turn valve used for shut-off application. The valve opens and closes the flow of the fluid via a built-in ball, that rotates inside the valve body. Ball valves are industry standard for on-off applications and are lighter and more compact than gate valves, which serve similar purposes. The two main designs are floating and trunnion (side or top entry)

    BUTTERFLY VALVE

    Butterfly valves are versatile, cost-effective, valves to modulate or open/close the flow of the fluid. Butterfly valves are available in concentric or eccentric designs (double/triple), have a compact shape, and are becoming more and more competitive vs. ball valves, due to their simpler construction and cost.

    PINCH VALVE

    This is a type of linear motion valve that can be used for throttling and shut-off applications in piping applications that handle solid materials, slurries, and dense fluids.  A pinch valve features a pinch tube to regulate the flow.

    PLUG VALVE

    Plug valves are classified as quarter-turn valves for shut-off applications. The first plug valves were introduced by the Romans to control water pipelines.

    SAFETY VALVE

    A safety valve is used to protect a piping arrangement from dangerous overpressures that may threaten human life or other assets. Essentially, a safety valve releases the pressure as a set value is exceeded.

    CONTROL VALVE

    Control valves are automated devices that are used to control and regulate the flow in complex systems and plants. More details about this type of valves are given below.

    Y-STRAINERS

    while not properly a valve, Y-strainers have the important function of filtering debris and protecting downstream equipment that may be otherwise damaged

    VALVE SIZES (ASME B16.10)

    To make sure that valves of different manufacturers are interchangeable, the face-to-face dimensions (i.e. the distance in mm or inches between the inlet and the outlet of the valve) of the key types of valves have been standardized by the ASME B16.10 specification.

    ASME B16.34: VALVE COMPLIANCE

    The ASME B16.34 standard, issued by the American Society of Mechanical Engineers (ASME), is a pivotal guideline that specifies the requirements for the design, material selection, manufacturing, inspection, testing, and marking of flanged, threaded, and welding end steel valves for application in pressure systems.

    ASME B16.34 is also mentioned in the more general ASME spec ASME B31.1, “Power Piping Design”.

    This standard is critical for ensuring the safety, reliability, and efficiency of valves used in various industrial sectors, including oil and gas, chemical, power generation, and water treatment, among others.

    Understanding the ASME B16.34 standard is essential for engineers, manufacturers, and end-users involved in the selection and application of valves.

    Key Aspects Of ASME B16.34

    1. Valve Design and Construction:
      ASME B16.34 sets forth the criteria for the design of valves, including dimensions, pressure-temperature ratings, and other factors essential for ensuring that valves can operate safely under specified conditions. It covers a range of valve types, such as gate, globe, check, ball, and butterfly valves.
    2. Pressure-Temperature Ratings:
      One of the most critical aspects covered by ASME B16.34 is the pressure-temperature rating of valves, which defines the maximum allowable working pressure for a valve at a given temperature. These ratings ensure that valves are selected and used within their safe operating limits.
    3. Material Specifications:
      The standard provides detailed specifications for the materials used in valve construction, including requirements for body, bonnet, trim, and gasket materials. These specifications ensure compatibility with the fluid being handled and the operating environment, contributing to the valve’s integrity and longevity.
    4. Testing and Inspection:
      ASME B16.34 outlines the requirements for testing and inspecting valves to verify their integrity and performance. This includes tests for shell strength, seat tightness, and backseat effectiveness, among others, which are crucial for ensuring that valves meet stringent safety and reliability standards.
    5. Marking and Documentation:
      The standard specifies the marking requirements for valves, which include the manufacturer’s identification, pressure-temperature rating, material designation, and other relevant information. These markings provide essential information for the identification, traceability, and selection of valves.

    Importance Of ASME B16.34 In Valve Selection

    Adherence to the ASME B16.34 standard is crucial for ensuring that valves perform safely and effectively in their intended applications. Engineers and procurement specialists rely on this standard to select valves that meet the necessary performance criteria, including compatibility with the process medium, operating pressures and temperatures, and durability requirements.

    Compliance with ASME B16.34 is also often a regulatory requirement in many industries, making it a key consideration in the procurement and installation of valves in critical applications.

    Valve Compliance To ASME B16.34

    A valve complies with ASME B16.34 when the following conditions are met:

    • The valve body & shell materials comply with ASME and ASTM material standards for chemistry and strength
    • Body & shell materials are heat-treated to ensure proper grain structure, corrosion resistance, and hardness.
    • Wall thicknesses of the body and other pressure-containing components meet ASME B16.34 specified minimum values for each pressure class.
    • NPT and SW end connections comply with ASME B1.20.1 or ASME B16.11.
    • Stems are internally loaded and blowout-proof.
    • All bolting will be ASTM grade with maximum applied stress controlled by B16.34.
    • Each valve is shell tested at 1,5x rated pressure for a specific test time duration.
    • Each valve is tested for seat leakage in both directions for a specific test time duration.
    • Each valve is permanently tagged with materials of construction, operating limits, and the name of the manufacturer.

    In conclusion, ASME B16.34 plays a fundamental role in the design, selection, and application of valves in pressure systems. It provides a comprehensive framework for ensuring that valves are safe, reliable, and suitable for their intended use, supporting the operational integrity of industrial processes across various sectors.

  • HOW TO ORDER A VALVE

    Manufacturers of valves used in the oil and gas industry need to know the following information to supply the right device:

    • Valve type
    • Bore size in NPS or DN
    • Valve pressure rating (class range from 150# to 4500#)
    • Specification (example API 6D, API 600, API 602, etc)
    • Body and trim materials (at least)
    • Required end connection (flanged, threaded, butt weld, lug and others)
    • Fluid in the pipeline (>oil, gas, water, steam, solids)
    • Working temperature and pressure
    • Quantity
    • Delivery time
    • Origin restrictions (Chinese and Indian origins allowed or not)

    EXAMPLE HOW TO ORDER OIL & GAS GATE, GLOBE, CHECK VALVES

    Each manufacturer has own valves ordering sheets that map the valve configuration parameters that user has to consider:

    GS – F – 6″ / 150 – 316 – B

      1    2        3           4      5

    1. Valve type 2. End type 3. Size / Class 4. Body Material 5. Options
    C: Check Valve
    CL: Lift Check Valve
    CS: Check pressure Sealed Valve
    CW: Swing Check Valve
    G: Gate Valve
    GG: Forged Gate Valve
    GL: Light Type Gate Valve (API 603)
    GS: Gate Pressure Sealed Valve
    O: Globe Valve
    OB: Globe Bellowed Sealed Valve
    OS: Globe Pressure Sealed Valve
    Y: Y-strainer    		 F: Flanged End
    T: Threaded End
    W: Butt Weld End
    S: Socket Weld End    		 Size: NPS 1/2 – 80″

    ANSI Standard:
    150: 150 LB Class
    300: 300 LB Class
    600: 600 LB Class
    1500: 1500 LB Class

    DIN Standard：

    PN16
    PN25
    PN40

    JIS Standard：

    10K: JIS 10K
    20K: JIS 20K

    		 GG: Forged Gate Valve
    316: Casting S.S CF8M
    304: Casting S.S CF8
    F316: Forgings S.S F316
    F304: Forgings S.S F304
    WCB: Steel WCB
    LCB: Steel LCB
    HB: Hastelloy B
    IN: Inconel    		 B: By-Pass
    G: Gear Operator
    D: Drains
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ASTM Materials for Valves: ASTM A216, A351, A352, A105, and A182 (Cast & Forged Grades)

Discover the essential AsTM material standards for valves., Valves larger than 2 inches typically have cast valve bodies, created by casting molten metals into molds, Forged valve bodies, suitable for smaller or high-pressure valves, are made by shaping and machining solid steel. The principal material specifications for cast steel valve bodies include ASTM A216 (WCA, WCB, WCC forstandard conditions, ASTM A352 LCB/LCC for low temperatures, and ASTM A351 CF8/CF8M for stainless steel valves. For forged valve bodies, the relevant ASTM standards are A105, A350, and A182.

CAST STEEL VALVES(ASTM GRADES)

DEFINITION OF CAST VALVE

Cast valves are valves whose bodies have been formed by pouring molten metal into a mold where it solidifies into the desired shape. This casting process allows for the creation of complex shapes and sizes, making it possible to produce valve bodies with intricate internal geometries that would be challenging or impossible to achieve through forging or machining alone. Cast valves are widely used across various industries due to their versatility in design, the ability to work with a wide range of materials, and their cost-effectiveness for producing large or complex valves, They are suitable for numerous applications, handling everything from water and steam to chemicals and gas, depending on the material used in the casting process Therefore, cast valves are characterized by a body made through casting, whereas forged valves possess a body created by forging. Essentially, the difference between cast and forged valves lies in the method used to construct the valve body material.specifically whether it involves steel forging or casting.
Let’s now delve into the most common cast valve body materials according to ASTM

ASTM A216 WCA, WCB, WCC (CARBON STEEL FOR HIGH-TEMPERATURE)

ASTM A216 is a specification established by the American Society for Testing and Materials (AsTM) that covers carbon steel castings for valves, flanges, fittings, and other pressure-containing parts for high-temperature service. The standard is divided into three grades: WCA, WCB, and WCC, with WCB being the most commonly used grade.
These 3 grades covered by the AsTM A216 specification differ mainly in their mechanical properties and temperature capabilities:

 

WCA is the grade with the lowest strength and temperature tolerance.
WCB is the intermediate grade, offering a good balance of strength and ductility across a wide range of temperatures.
WCC has higher strength and impact properties at low temperatures compared to WCB.
ASTM A216 specifies the chemical composition, mechanical properties, heat treatment, and testing requirements to ensure the material’s quality and durability under high-temperature condition This standard is commonly applied in the manufacturing of components for industrial boilers, pressure vessels, and other equipment where robust performance at elevated temperatures is required.
The ASTM A216 specification applies to cast valves that match carbon steel pipes in grades A53, A106, and API 5L.
ASTM A216 steel castings shall be heat treated and can be manufactured in annealed, normalized, or normalized tempered conditions.The surface of steel castings shall be free of adhering elements such as sand, cracks, hot tears, and other defects.

Notes:
1., for each reduction of 0.019% below the specified maximum Carbon content, an increase of 0.04% of manganese above the specified maximum is allowed up to a maximum of 1.10%.
2. For each reduction of 0.01% below the specified maximum Carbon content, an increase of 0.0496 Mn above the specified maximum is allowed up to a maximum of 1.28%.
3. For each reduction of 0.01% below the specified maximum Carbon content, an increase of 0.04% of manganese above the specified maximum is allowed to a maximum of 1.40%.

ASTM A352 LCB/LCC (CARBON STEEL FOR LOW-TEMPERATURE)
ASTM A352 is an ASTM (American Society for Testing and Materials standard specification that covers steel castings for valves,flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service. The standard includes several grades of carbon and alloy steel castings that vary in their mechanical properties and chemical compositions to suit different environmental conditions and temperature ranges.
The grades under ASTM A352 are designed to perform reliably in environments where temperatures may fall below freezing, making them suitable for applications in cold climates or in processes requiring cryogenic temperatures.

 

Key grades within this specification include:
LCB: A grade of carbon steel castings suitable for low-temperature applications where temperatures can go as low as-46°C (-50°F).
LCC: Similar to LcB but with improved impact strength at lower temperatures, making it suitable for even more demanding
low-temperature environments.
LCl, LC2, LC3, LC4: These are alloy steel grades within AsTM A352, each designed for specific low-temperature ranges and applications, with Lc3, for example, being nickel steel castings intended for service down to -01’C -150°F).

Each grade specified in ASTM A352 has defined requirements for chemical composition, mechanical properties such as tensile strength, yield strength, and elongation), and toughness to ensure the castings perform adequately under the specified service conditions, The standard also outlines requirements for heat treatment, quality, and test methods to verify the properties of the castings.
ASTM A352 is widely used in the oil and gas industry, petrochemical plants, and other applications where materials are exposed to low temperatures and require a high level of toughness to prevent brittle fracture.
The ASTM A352 specification applies to cast valves that match carbon steel pipes for low-temperature applications in grades A333.
Chemical composition of A352 cast valves Gr, LCA/LCB/Lcc (valve material chart)

valve material chart

ASTM A351 CF8/CF8M (STAINLESS STEEL FOR HIGH-TEMP. & CORROSIVE SERVICE)

ASTM A351 is a standard specification established by the American Society for Testing and Materials (ASTM) that covers castings of austenitic steel for valves, flanges, fittings, and other pressure-containing parts. This specification is particularly focused on stainless steel castings that are intended for high-temperature service. The ASTM A351 standard includes several grades, each with specific chemical compositions and mechanical properties to suit different environments and applications.

Key grades under ASTM A351 include:

  • CF8: Equivalent to 304 stainless steel, this grade is known for its good corrosion resistance and is widely used in general applications.
  • CF8M: Equivalent to 316 stainless steel, CF8M offers enhanced corrosion resistance due to its molybdenum content, making it suitable for more corrosive environments such as those encountered in chemical processing.
  • CF3 and CF3M: These are the low-carbon versions of CF8 and CF8M, respectively, offering similar corrosion resistance but with improved weldability and reduced susceptibility to intergranular corrosion after welding or heating.

The standard specifies requirements for chemical composition, mechanical properties, heat treatment, and testing procedures to ensure the quality and performance of the castings. ASTM A351 stainless steel castings are commonly used in applications requiring good corrosion resistance at both ambient and elevated temperatures, including the chemical industry, food processing, and petrochemical operations, among others.

Any ASTM A351 cast part shall receive heat treatment followed by a quench in water or rapid cooling. The steel shall conform to the chemical and mechanical requirements set by the specification. The steel shall be made by the electric furnace process with or without separate refining such as argon-oxygen decarburization.

The ASTM A351 specification applies to cast valves that match stainless steel pipes for high-temperature and corrosive applications applications in ASTM A312.

 

ASTM A351 stainless steel valves, chemical composition

 

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Valve Material ASTM, DIN, JIS Convertion Chart

Valve Material ASTM, DIN, JIS Convertion Chart

Valve Material ASTM, DIN, JIS Convertion Chart

The following material is commonly used for valves.

ASTM DIN EN10213 DIN EN No. UNS JIS Trademark
A216 WCB GP240GH 1.0619 J03002 SCPH2  
A352 LCB G20Mn5 1.0622 J03003 SCPL1  
A352 LC3 G9Ni14 1.5638 J31550 SCPL31  
A217 WC1 G20Mo5 1.5419 J12524 SCPH11  
A217 C5 GX15CrMo5 1.7365 (1.7363) J42045 SCPH61  
A217 C12 GX12CrMo10-1 1.7389 J82090    
A351 CF3 X2CrNi19-11 1.4306 J92500 SCS19  
A351 CF3M X2CrNiMo17-12-2 1.4404 J92800 SCS16  
A351 CF8 GX5CrNiMo19-10 1.4308 J92600 SCS13  
A351 CF8C GX5CrNiNb19-11 1.4552 J92710    
A351 CF8M GX5CrNiMo19-11-12 1.4408 J92900 SCS14  
A351 CF8MC GX5CrNiMoNb19-11-2 1.4581      
A351 CG8M          
  GX2CrNiMoN22-5-3 1.447      
           
A351 CK3MCuN          
A351 CN7M     N08007 SCS23  
A494 N-12MV     N10001   HASTELLOY B
A494 CW-12MW     N10002   HASTELLOY C
A494 M35-1     N04400   MONEL 400
A494 CW-6MC     N06625   INCONEL 625
      N08825   INCOLOY 825
      S31803   SAF 2205
      S31254   254 SMO
      S32550   FERRALIUM 255
Material Comparison
Casting Forging
ASTM EN 10213 EN No. ASTM EN 10213 EN No.
A216 WCB GP240GH (GS-C 25N) 1.0619 A105 C22.8 1.046
A352 LCB G20Mn5 1.622 A352 LF2   1.0437
A352 LC3 G9Ni14 1.5638 A352 LF3   1.5637
A217 WC1 G20Mo5 1.5419 A182 F1   1.5415
A217 WC6 G17CrMo5-5 1.7357 A182 F11 14CrMo405 1.7335
A217 WC9 GS12CrMo9-10 1.738 A182 F22   1.738
A217 C5 GX15CrMo5 1.7365 A182 F5   1.7362
-1.7363
A217 CA15     A182 F6 X20Cr13 1.4021
A217 C12 GX12CrMo10-1 1.7389 A182 F9 15CrMo12.1 1.492
A351 CF3 X2CrNiMo17-12-2 1.4406 A182 F304L X2CrNi19-11 1.4306
A351 CF3M X2CrNiMo17-12-2 1.4404 A182 F316L X2cRNImO17-12-2 1.4404
A351 CF8 GX5CrNiMo19-10 1.4308 A182 F304 X5CrNi18-10 1.4301
A351 CF8C GX5CrNiNb 19-11 1.4552 A182 F321 X6CrNiTi18-10 1.4541
A351 CF8C GX5CrNiNb 19-11 1.4552 A182 F347 X6CrNiNb18-10 1.455
A351 CF8M GX5CrNiMo19-11-2 1.4408 A182 F316 X5CrNiMo17-12-2 1.4401
A351 CF8MC GX5CrNiMoNb19-11-2 1.4581 A182 F348 X6CrNiMoNb17-12-2 1.458
A351 CG8M GX2CrNiMoN22-5-3 1.447 A182 F317    
A351 CK3MCuN     A182 F44    
A351 CN7M     A182 F20  

 

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What is the difference between a foot valve and a check valve?

In short, a foot valve and a check valve are very similar in that they automatically open or close depending on system pressure, allowing flow in only one direction and preventing backflow. Figure 1 shows a check valve on the right and a foot valve on the left, with the main visual difference being that the foot valve has a strainer on it. Given the similarities between the two valves, there are important differences. Foot and check valves have different installation locations in a system, different material requirements, and different designs. This article will focus on these key differences. Read our comprehensive articles about check valves and foot valves to learn more about each type of valve.

Operation principle

Understanding how check and foot valves work is helpful before discussing their differences. Both valve types open when the inlet pressure is above the valve’s cracking pressure. The cracking pressure is the minimum amount of pressure required to open the valve and overcome the force keeping the valve closed (spring or gravity). When the inlet pressure reduces below this limit, or there is backpressure, the valve closes shut.

Differences between check valves and foot valves

Design

Foot and check valves have a variety of design types, for example, ball check valves and ball foot valves. This section, though, focuses on the design differences that exist between all check and foot valves.

  • Screen: The first visual difference is the screen attached to the foot valve’s inlet end, which is often called a strainer or filter. Foot valves typically sit submerged in water in a well. The screen prevents larger debris from entering the foot valve and sticking the valve’s disc open and damaging other components within the system. A check valve does not have this protection and therefore is not applicable for media that has large solids in the flow.
  • Threading: A check valve has threading on both sides. So, a check valve fits into any part of the piping deemed appropriate. Removing a section of the pipe and installing a check valve is a straightforward process. Foot valves, however, have threading only on one side. Therefore, foot valves are only suitable for the end of a pipe, which is the end of a pump’s suction line.

Material

The key material difference between foot and check valves is that foot valves are in water for the duration of their use. Therefore, whichever material selected must be corrosion resistant. Materials often chosen are PVC, heavy-duty cast iron, bronze, and stainless steel.

Check valves have a wider range of material options because they operate in a wider range of environments. When selecting a check valve material, first understand the system’s pressure, temperature, and operating environment. Read our chemical resistance guide to learn more.

Installation

Because foot valves work on pump systems, this section will only cover the installation locations of check and foot valves on these systems. Both valves stop media from flowing back into the well when the pump turns off, thus keeping the pump primed.

A jet pump uses a foot valve at the very end of its suction line. In contrast, a submersible pump has a foot valve directly installed on its inlet. Both pump systems can use check valves in the same locations. However, this is not suitable for any wells that may contain solids large enough to get stuck in the valve and hinder its operation.

Deep well systems use one or more extra check valves along the suction line to protect the submersible pump and foot valve from the water column’s pressure. Shallow well systems may have a check valve on the suction line. Also, check valves can install directly at the jet pump’s inlet or between the jet pump and pressure tank. Beyond stopping backflow into the well, check valves are applicable anywhere where backflow may damage an upstream component or contaminate upstream media.

Foot valve and check valve P&ID symbols

Figure 2 depicts a check valve symbol (left) and a foot valve symbol (right).

Check valve symbol (left) and foot valve symbol (right).Figure 2: Check valve symbol (left) and foot valve symbol (right).

Summary

Table 1: Comparison between foot valve and check valve

Foot valve Check valve
Design A foot valve has a strainer on the inlet side. A check valve does not have a strainer.
Material Foot valves have a limited selection of materials: stainless steel, heavy-duty cast iron, PVC, and bronze. Check valves have more material options because they do not rest in water.
Application Foot valves are used for suction lift applications, like a well pump. Check valves are applicable for pump systems and any system that requires backflow prevention.
Installation Foot valves only go at the end of a pump’s suction line. Check valves can go at the end of a suction line, in the middle of the suction line, and anywhere else in the system where necessary.
Threading Foot valves have threading on the outlet side only. Check valves have threading on both sides.

FAQs

What is the difference between a foot valve and a check valve?

A foot valve has a screen on its inlet side to prevent large solids from entering the valve. Also, it fits at the end of a suction line in a pump system. A check valve is suitable for any system, including pump systems, that require media to flow in only one direction.

Can a check valve be used in place of a foot valve?

Yes, a check valve can be used in place of a foot valve. However, check valves do not have a protective screen and any large solids in the media can stick them in the open position.

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How to Select the material for Gate Valve

Selecting the right gate valve material is crucial in the gate valve selection process. Various materials are used for the gate valve’s body and seal. The material selection depends primarily on the media type and design temperature. This article discusses the common materials used in gate valves and how to find the right one for each application.

Gate valve material selection

Gate valves are used in a wide range of applications, and they come in contact with diverse media. It is critical to consider the material used for valve construction to prevent premature valve failure and system delays during valve operation. Consider the following criteria to select the proper materials for a gate valve:

  1. Media composition (whether clear or filled with particles)
  2. Material compatibility with the media used
  3. How long the valve gets exposed to the media
  4. Operating pressure
  5. Service temperatures
  6. Effectiveness of coating on materials
  7. Material availability and cost

Gate valves are available in various materials, as discussed in the next section. Various organizations are committed to developing and maintaining standards for valves and materials in specific environments. For example, gate valves are specified by the American Petroleum Institute (API) and the National Association For Corrosion Engineers (NACE) for their suitability to work with heavy corrosive media.

Gate valve body materials

The various materials used to construct gate valve body are discussed below.

PVC gate valve

PVC gate valve gate-valve-pvc.jpegFigure 2: PVC gate valve

In a PVC gate valve, the valve’s three main components, namely, the handle, housing, and gate, are made of PVC.

PVC gate valve features

  • PVC gate valves are not damaged by freezing temperatures, and these valves can also withstand temperatures up to 60°C.
  • Resistant to corrosion, making these valves ideal for chemical processing applications involving highly corrosive substances.
  • PVC valves are affordable compared to metal valves.
  • Excellent durability offering many years of reliable use.
  • Available in a wide range of sizes.

PVC gate valve applications

PVC gate valves are a good low-cost solution for most flow control needs at home. These valves are durable and corrosion-resistant, hence widely used in aquatic environments. A few common applications are:

  • Aquatics and aquaculture
  • Landscaping and irrigation
  • Tank drain valves and septic systems
  • Indoor plumbing
  • Spas

Brass gate valve

In applications where PVC gate valves would burst, it is a viable option to use gate valves made of metals or their alloys.

Brass gate valve features

  • Brass gate valves work on 0-16 bar pressure range with media temperatures from -20°C to 120°C. Hence, they can withstand higher temperatures and pressure than PVC gate valves.
  • Brass is stronger than PVC, but stainless steel is the strongest.
  • Brass gate valves are costly compared to PVC gate valves, but less costly than stainless steel gate valves.

Brass gate valve applications

Brass can withstand more heat than PVC, making them an ideal choice for residential plumbing applications. Brass is extremely corrosion resistant, and the gate valves made of brass are ideal for manufacturing industries involving natural gas or potable water.

Stainless steel gate valve

Stainless steel gate valveFigure 3: Stainless steel gate valve

Stainless steel gate valve features

  • Stainless steel is the most durable, heat-resistant, and corrosion-resistant material when compared to brass and PVC.
  • Withstands very high temperature (up to 800°C) and pressure. Stainless steel can withstand a wide range of temperatures (low to high) and pressure compared to brass and PVC.
  • Used to manufacture gate valve body and internal parts
  • Stainless steel gate valves have a simple body design enabling ease of repair, cleaning, and maintenance
  • Used in applications involving liquid, gas, and steam
  • Expensive compared to PVC, brass, and bronze gate valves
  • Needs a large area for installation compared to brass or PVC

Stainless steel gate valve applications

Stainless steel is extremely durable and corrosion-resistant, hence used in marine and industrial applications. Some common applications are:

  • Industrial applications like transporting natural gas and crude oil
  • Slurry applications
  • Drinking water applications at home as the material doesn’t leach into the water

Bronze gate valve

Bronze gate valveFigure 4: Bronze gate valve

Bronze gate valve features

  • Excellent machinability, strength, and corrosion resistance
  • Used to manufacture relatively small gate valves in low-pressure applications
  • Bronze gate valves are typically used for water pipes and equipment pipelines of about 300 psi (20 bar) or less, and temperatures in the range -20° C -150° C.
  • Higher cost compared to PVC, but less than brass and stainless steel
  • Bronze has higher corrosion resistance than cast iron, but less than PVC or brass.
  • Costlier than PVC but the cost is lower than brass or stainless steel.

Bronze gate valve applications

Bronze has high lead content; hence the material is not used frequently for drinking water applications. Bronze is commonly used for fluid control in low-pressure manufacturing industries and works well with steam, air, and gas. The material is also used in HVAC and marine applications.

Cast iron gate valve

Cast iron gate valveFigure 5: Cast iron gate valve

Cast iron gate valve features

  • Cast iron has strength lying in between bronze and stainless steel
  • Used to manufacture gate valve body
  • Very low tensile strength and elongation properties, but good casting qualities
  • Cast iron gets corroded over time.
  • Less costly compared to all other valve materials.

Cast iron gate valve applications

Cast iron is used for constructing gate valves in low-pressure and low-temperature applications. The material is a popular choice for gate valves in water, wastewater, heating, ventilation, and air-conditioning (HVAC) units. Cast iron gate valves are extremely cheap, yet sturdy; hence these valves are more suitable for underground applications than steel valves.

Cast steel gate valve

Cast steel gate valve feature

  • Casted carbon steel is a tough material, and the material is hard with excellent tensile strength and impact value.

Cast steel gate valve application

  • Gate valves made of cast steel are commonly used in industrial plants for high temperature and pressure applications.
Cast steel gate valves used in industrial plantsFigure 5: Cast steel gate valves used in industrial plants

Gate valve seal materials

Gate valve seats are available in two forms:

  • Integrated-type: The gate valve seal is made of the same material as the valve body and it is integrated into the valve body.
  • Ring type: In this type, the gate valve seal is in the form of a ring that can be either pressed in or threaded which favors more variation. The seat can be coated with polytetrafluoroethylene (PTFE) to aid high-integrity shutoff. The ring-type seal is again classified into resilient-seated and metal-seated gate valves:
    • Resilient seated gate valves: The gate is mostly composed of ductile iron and enclosed in a resilient elastomer material like ethylene propylene diene monomer (EPDM) forming a tight seal. These valves are preferred in water distribution systems because of the tight shut-off.
    • Metal-seated gate valves: Ductile iron is commonly used as the gate material, and rings are made of bronze to ensure a watertight seal.
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What is the difference between standard port and full port ball valves?

A ball valve is a type of valve that controls the flow of fluids through piping systems. Depending on the intended application, ball valves have a variety of designs. Based on the port size, a ball valve can be classified as either a full port, standard port, or reduced bore ball valve. This article compares the various advantages and disadvantages of each ball valve type. Read our ball valve overview article for more details on the working and design of ball valves.

Ball valves based on port size

Full port ball valve

A full port or full bore ball valve is a type of ball valve where the inlet and outlet pipes have the same diameter as the bore in the valve. In simple terms, the valve port is the same size as the pipe resulting in a full flow ball valve. For a full port ball valve, there is little or no resistance to the flow of fluids, and the flow path is straight.

Standard port ball valve

In a standard port ball valve, the size of the bore in the ball is smaller than the size of the inlet and outlet pipes. The diameter of the flow path through the ball valve is narrower on the interior. The standard port ball valve creates resistance to flow, increasing its fluid pressure. The flow path is usually straight.

Reduced port ball valve

In reduced bore ball valves, the port in the ball valve is one pipe size narrower than the inlet and outlet pipes. In other words, the diameter of the bore is one specification smaller than the pipes’ diameter specification. The fluid flowing through a reduced port valve has a higher velocity.

Full port (left) and reduced port (right) ball valvesFigure 2: Full port (left) and reduced port (right) ball valves

Comparison between full port, standard port, and reduced port ball valves

As the features of reduced port and standard port ball valves are identical in all aspects both valve types are grouped into one throughout the comparison process as seen below.

Port size

  • Reduced/standard port ball valves: The valve port is smaller than the pipe diameter.
  • Full port ball valves: The size of the valve port is the same as that of the pipe diameter.

Media

Media is the fluid flowing through the pipes and the ball valve. The media can be solids, liquids, or gases.

  • Reduced/standard port ball valves: Reduced or standard port ball valves are helpful to convey plain fluids like gasses or water. These valves transport light media in general.
  • Full port ball valves: The full-bore ball valves are suitable forviscous fluids because it offers little or no flow resistance. Examples of viscous fluid include paraffin, glycerin, etc.

Pipeline and flow control

  • Reduced/standard port ball valvesReduced and standard port ball valves offer a flow resistance, thus producing a pressure drop. The flow path through the valve becomes narrower on the valve’s inside. Reduced or standard port ball valves are ideal for relaxed working conditions where pressure drop does not affect pipe performance. This is because these valves reduce the velocity of the medium and hence suitable for applications where flow resistance is acceptable.
  • Full port ball valves: A full port ball valve has a straight flow path and offers little or no resistance to the media flow. The flow path through a full port ball valve does not become narrower on the inside. Full-bore ball valves are the only option for piping systems under strict working conditions. Underground pipes, regardless of the medium, must only use full port ball valves. When it comes to pipeline control, full port valves are ideal.

Pigging applications

Pigging is the process of cleaning a gas pipeline where a device known as a pig travels through the pipeline. This process is not supported by certain valve types that do not allow the free travel of pig through the connected valve.

  • Reduced/standard port ball valves: Reduced port ball valves have different diameters for the bore and connecting pipe; hence the pigging device cannot travel freely through a reduced bore ball valve for cleaning purposes.
  • Full port ball valves: In an open state, the bore of a full-port ball valve is parallel to the inlet and outlet ports; hence, there is no visual difference between the valve and pipe bores. In this way, a pig can have an unrestricted flow through the valve, thereby cleaning the bore of the valve along with the entire pipeline.

Cost

  • Reduced/standard port ball valves: A reduced or standard port ball valve has a compact body and thus lower costs.
  • Full port ball valves: Purchasing a full port ball valve requires a larger initial investment than purchasing a reduced port ball valve. The full port is more expensive because many materials are used in its construction. Because of its effective performance, a full-port ball valve is cost-effective in the long run.

Fitting space

Fitting space is the amount of space the ball valve will occupy when installed.

  • Reduced/standard port ball valves: A reduced/standard port ball valve has a small volume and thus requires little space.
  • Full port ball valves: A full-port ball valve has a large volume necessitating more space.

Transportation

  • Reduced/standard port ball valves: The small volume and lightweight properties of a reduced port ball valve make it easy to transport.
  • Full port ball valves: The full-port ball valve is heavy and has a large volume. This makes its transportation difficult and costly.

Full port ball valve with a drain

A full port ball valve with a drain is essential for preventing fluid or condensation buildup inside the valve. Failure to drain the valve can damage the valve. Draining is done to replace contaminated and stale fluids within the valve. Draining relieves any pressure that has built up within the valve. To drain a ball valve, first, allow fluid to flow into the drain by opening the valve. Then, close the valve to prevent fluid from flowing through it. Finally, open the valve and allow the fluid to drain. Read our article on condensate drain valve for more information.

3-way full port ball valve

A 3-way full port ball valve has three ports. These valves are available with either an L or T-port design. The L and T designation refers to the internal bore design, determining the media’s flow direction. A 3-way ball valve with a T or L port allows for mixing, distribution, or diverting the flow direction for different applications. To open a 3-way, rotate the ball until the ports are aligned with the corresponding ports, allowing fluids to flow through. To close, rotate the ball back to the closed position. When the ports are closed, they are out of place and not aligned with one another.

Comparison chart

Table 1: Comparison between standard/reduced and full port ball valve port designs

Standard/reduced port ball valve Full port ball valve
Pipeline control Not ideal Ideal
Cost Low initial cost High initial most
Fitting space Less More
Transportation Easy Difficult
Pigging applications Not ideal Ideal

FAQs

What is the difference between standard port and full port ball valves?

In a full port ball valve, the ports of the valve have the same diameter as the connecting pipes. The valve port size is smaller than the pipe diameter in a standard port ball valve.

Why is the standard port more common than the other types of ball valves?

The design of a standard port ball valve is convenient for most applications. It is compact, relatively light, and less expensive.

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Which valve is better between globe valves and ball valves?

Globe valves and ball valves are both shut-off valves typically used in piping systems. However, it is usually not immediately obvious which valve is most suitable for an application. System design should be finished before valve selection in order to select the best valve for the job in terms of cost, installation space, flow control, and more. Keep reading to learn more about how a globe valve may be more suitable than a ball valve and vice versa.

Working principles

Globe valve working principle

A globe valve in the open position (left) and the closed position (right) with the valve stem (A), stem (B), plug (C), and body (D).Figure 2: A globe valve in the open position (left) and the closed position (right) with the valve stem (A), bonnet (B), plug (C), and body (D).

A globe valve is a multi-turn valve, meaning that the handwheel needs to be turned more than 360° to fully open or close the valve. The main components of a globe valve are the valve body, bonnet, handwheel, stem, and plug. Media flows into the valve body (Figure 2 labeled D) through an inlet and exits the valve body through an outlet. The bonnet (Figure 2 labeled B) protects the threaded components of the valve and attaches to the valve body. As the user turns the handwheel, it turns the threaded stem (Figure 2 labeled A), which raises or lowers the plug (Figure 2 labeled C). Raising the plug opens the orifice, thereby allowing media flow. Lowering the plug into the valve seat seals the orifice, preventing the flow. Raising the disc, on the other hand, increases the flow rate. The flow rate is maximum when the disc is raised to its maximum position. The fluid flow rate is controlled by moving the disc proportionally through the stem.

Ball valve working principle

Ball valve parts; Stem (A), o-rings (B), body (C), ball (D), and seat (E)Figure 3: Ball valve parts; Stem (A), o-rings (B), body (C), ball (D), and seat (E)

A ball valve is a quarter-turn valve, meaning that the handle only needs a 90° turn to fully open or close the valve. The main components of a ball valve are shown in Figure 3. The stem (Figure 3 labeled A) connects to the ball (Figure 3 labeled D). The ball sits on the ball valve seat (Figure 3 labeled E), creating the seal. O-ring stem seals (Figure 3 labeled B) are used to prevent leakage. All of these components are within the valve housing (Figure 3 labeled C). As seen in Figure 3, the ball has a bore running through it. Under normal operation, the bore is either aligned with the valve ports to allow flow, or perpendicular to the ports to block flow. Read our article on ball valves for more details on how they work.

Flow control

Globe and ball valves are both used to turn on or off the flow. Globe valves, though, can also function in a partially open or closed state to modulate the flow. This flow regulation is achievable due to the globe valve’s disc sitting parallel to the flow. The linear flow rate achieved by globe valves is higher than that achieved by ball valves, and reduces the effects of water hammer.

Head loss

Globe valves have significantly higher pressure loss (head loss) in the fully open position than ball valves. This is because the fluid has to change direction multiple times as it passes through a globe valve.

Valve design

Globe valve design

Globe valves are available in three basic configurations: T- or Z globe valve, Y-globe valve, and angle globe valve. Read our article on globe valves for more information on each type.

Ball valve design

The ball valve can be classified into different categories depending on its housing structure, ball design, and port size. Depending on the housing structure, we can have 1, 2, or 3-piece ball valves. Depending on the port size, ball valves are categorized as full port ball valves, standard port ball valves, or reduced port ball valves. And depending on the number of ports, ball valves are classified into 2-way and multiport valves.

Symbols

  • Figure 4 shows the symbols for various globe valve configurations.
Globe valve symbols: globe (A), hand operated (B), pneumatic (C), motor operated (D), hydraulic operated (E).Figure 4: Globe valve symbols: globe (A), hand operated (B), pneumatic (C), motor operated (D), hydraulic operated (E).

The symbols for a ball valve are shown in Figure 5. For more details on the symbols of various ball valve configurations, read our article on ball valve symbols.

Actuated ball valve symbols; manually operated ball valve (A), pneumatically actuated ball valve (diaphragm type) symbol (B), pneumatically actuated ball valve (rotary piston type) symbol (C), electrically actuated ball valve symbol, and a hydraulic actuator ball valve symbol (D).Figure 5: Actuated ball valve symbols; manually operated ball valve (A), pneumatically actuated ball valve (diaphragm type) symbol (B), pneumatically actuated ball valve (rotary piston type) symbol (C), electrically actuated ball valve symbol (D), and a hydraulic actuator ball valve symbol (E).

Applications

Globe valves are used to control fluid flow. Furthermore, globe valves are advantageous in applications requiring precise throttling. Ball valves, on the other hand, are commonly used for plumbing system shut-off and isolation. Industrial applications for globe valves include fuel oil systems and cooling water systems, while those of ball valves include chemical storage and natural gas industries.

Globe valve and ball valve similarities

Globe valves and ball valves share some similarities. Both valves are used in piping systems to control the flow of liquids and gasses. Both are shut-off valves designed to allow or block the fluid flow within a pipe. Globe valves and ball valves can be operated manually or automatically.

Pros and cons of ball valves and globe valves

  1. Operation: Ball valves are simple and easier to operate than globe valves.
  2. Throttling: Globe valves are suitable for throttling operations, whereas ball valves should be either fully shut or fully open.
  3. Handle: Ball valves are quarter-turn valves which means the ball valve handle must be turned by 90° to go from fully open to a fully closed state or vice versa. The handwheel of globe valves must be turned multiple times from entirely closed to fully opened.
  4. Cost: Due to their simple structure, ball valves are cheaper than globe valves.
  5. Space: Globe valves occupy more space compared to ball valves.
  6. Pressure rating: Ball valves can handle higher pressure than globe valves.
  7. Durability: Ball valves are longer-lasting than globe valves.
  8. Leakages: Globe valves are more prone to leakages than ball valves.
  9. Media flow resistance: A globe valve offers more resistance to media flow compared to ball valves.
  10. Head loss: Globe valves have a higher head loss than ball valves.

Globe valve and ball valve selection

The selection between a ball valve and a globe valve depends on the intended purpose. The main factors to consider during the selection process are discussed below:

  1. Flow rate: Ball valves are desirable in applications where a high flow rate is necessary due to their full-bore design.
  2. Pressure drops: Ball valves have lower pressure drops because flow moves straight through them.
  3. Maintenance: Ball valves are simple to maintain because the valve only needs a little lubrication to stay clean. Further maintenance is necessary upon debris buildup.
  4. Temperature: Ball valves function better under high-temperature conditions due to their durable construction.

FAQs

What are the typical applications of a globe valve?

Globe valves are used commonly to control water flow in irrigation systems, regulate airflow in AC systems, and control oil flow in pipelines.

What is the main difference between a ball valve and a globe valve?

The ball valve has a hollow ball that rotates inside the valve, whereas the globe valve has a disc that moves vertically through the valve stem.

Which valve is better between globe valves and ball valves?

This depends on the intended application. Globe valves are better for throttling applications, while ball valves offer better performance as shutoff valves.

View our online selection of globe and ball valves!

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What is the advantage of gate valves over globe valves?

Despite their similarities at first inspection, globe and gate valves have significant differences that make each suitable for their applications. When choosing between these two valves for an application, understanding the application’s pressure, sealing, and flow requirements can ensure the correct valve is selected. This article discusses the differences between globe and gate valves to allow an educated decision before choosing between the two valves.

Globe valve vs gate valve comparison

Globe valves and gate valves are multi-turn, linear motion valves, meaning both valves require multiple turns to open or close. The closing mechanism moves up and down in a straight line to turn open or close the valve. At this point, similarities between the valves begin to diminish.

The globe valve differs from most valves because its name derives from its body shape (rounded) rather than its disc, which is the gate valve’s convention. Its disc moves up and down to allow or block the flow, similar to a gate. Read more on globe valves and gate valves to get a comprehensive understanding of both.

Flow properties

As seen in Figure 2, a gate valve is a straight-through, bi-directional valve, meaning its design permits flow directly through it in both directions. The only change to the flow occurs when the gate valve is closed, and the flow stops.

A gate valve flow properties when it is closed (left) and open (right).Figure 2: A gate valve flow properties when it is closed (left) and open (right).

A globe valve, on the other hand, has more turns for the flow path. As seen in Figure 3, the flow can take a z-shaped path (T- or Z-valve), an oblique path (Y-valve), or a 90° turn path (angle valve).

Because a globe valve diverts flow in a specific way, it has an inlet and an outlet port. Typically, an arrow on the outside of the valve’s body will indicate the valve’s flow direction. Also, the flow diversion causes a significant pressure drop through the globe valve. In contrast, a gate valve’s pressure drop is nearly non-existent.

Globe valves' flow paths: T- or Z-valve (left), angle valve (center), and Y-valve (right)Figure 3: Globe valves’ flow paths: T- or Z-valve (left), angle valve (center), and Y-valve (right)

Valve functions

Both gate valves and globe valves can operate as on/off valves. A gate valve is not meant to bused to throttle flow, but a globe valve can. Flow diverts within the globe valve and becomes parallel to the valve seat. This design makes globe valves efficient flow throttlers. Globe valves become unsuitable for throttling flow at larger diameters (above DN 150). Gate and globe valves can be operated mechanically, pneumatically, or electrically.

Note: With other factors equal, Y-valves are the least efficient at throttling flow because the valve seat is not parallel to the flow direction. However, this also means that Y-valves have the smallest pressure drop.

Visual differences

At a quick glance, gate valves and globe valves are not easy to tell apart. The following traits are what to look for to tell the difference:

  • Body: Gate valves usually have a rectangular or wedge-shaped body. Whereas the body of a globe valve is rounder, especially at its bottom.
  • Maximum height: Gate valves usually are higher when opened than globe valves.
  • Flow direction indicator: Gate valves are bi-directional, whereas globe valves are unidirectional. A marker on the valve, such as an arrow, indicates the flow direction and that it’s a globe valve.

Advantages and disadvantages chart

Globe and gate valves may have similar or different materials for their housing and seals. Read our chemical resistance guide to learn more about the advantages and disadvantages of the various materials. See the following chart to learn about more advantages and disadvantages.

Table 1: Globe valve and gate valve advantages and disadvantages chart

Globe valve Gate valve
Application Used for flow regulation (e.g., cooling water systems and fuel oil systems) More suitable for slurry due to less space in the valve’s body for sediment to get stuck and build up
Flow control Can be used or on/off control and can throttle flow Can be used for on/off control and cannot regulate the flow
Flow capacity Lower Higher
Flow direction Unidirectional Bi-directional
Flow restriction/pressure drop Flow diversion within the valve’s body creates significant pressure drop Full-bore valve, meaning there is no reduction to flow and pressure drop is insignificant
Power requirement Needs a large amount of force or an actuator to close under high pressure Needs less power to close under high pressure
Operating conditions Can operate at higher temperatures Can operate at higher pressures
Cost More expensive than a gate valve due to its complicated structure Cheaper
Leakage More effective sealing because force is applied to the disc when closed Good sealing properties
Installation space Takes up less vertical space, but requires more horizontal space If a rising-stem style, needs more vertical space, but less horizontal space
Weight Heavier Lighter
Ports Can have a 3-port configuration for straight-through flow Two ports

Selecting between globe valves and gate valves

Gate valves and globe valves are both excellent shut-off valves. However, when choosing between them, neither valve will outperform the other in every single application. Consider the following factors:

  • Flow control: Select a globe valve if an application requires flow modulation.
  • Flow capacity: Choose a gate valve if an application demands high flow.
  • Flow direction: Choose a gate valve if an application requires bi-directional flow.
  • Pressure drop: Select a gate valve if a minimal pressure drop is necessary.
  • Sealing: If an application demands excellent sealing, select a globe valve.
  • Contaminated media: Choose a gate valve if an application has slurry or other contaminated media.

The above variables are typically the most important when selecting a shut-off valve. Refer to Table 1 for further information.

Example applications

Globe valves

  • Cooling water systems: Globe valves operate in cooling water systems by controlling the water flow to maintain a desired temperature.
  • Chemical injection systems: Globe valves work well in industrial systems that need control over chemicals into reaction vessels or process streams.

Gate valves

  • Bulk material handling systems: Heavy-duty processes (e.g., mining, agriculture, and construction) use gate valves to control the flow of bulk materials such as grains, coal, and aggregate.
  • Water distribution systems: Many components of a water distribution system do not require precise flow control. Therefore, gate valves are suitable because they either block or allow flow.

FAQs

Which is better? A gate valve or a globe valve?

Globe valves have better sealing than gate valves and last longer. However, gate valves have significantly lower pressure drop.

What is the advantage of gate valves over globe valves?

One significant advantage of gate valves over globe valves is that they require significantly less power to close since they close perpendicular to flow rather than parallel as globe valves do.

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What is the difference between a gate valve and a plug valve

Plug and gate valves are both stop-valves suitable for a wide array of applications and media types. For example, they can both be used for clean media and media containing solids or stringy material. Therefore, it may be difficult to determine which is more suitable for a specific application. This article looks closer at the similarities and differences between gate valves and plug valves to help ensure the correct valve is chosen and used for varying applications.

Before deciding between the two valves, it is important to consider the following:

  • The number of ports needed
  • How fast the valve needs to operate
  • The pressure and temperature of the planned system
  • Installation space available

  • Plug vs gate valve comparison

    Plug and gate valves are named after the method that each uses to allow or block flow. A plug valve uses a plug with an opening running through it. When a gate valve is closed, its disc sits perpendicular to and blocks the flow, operating much like a gate.

    Operating principles

    Plug valves are quarter-turn valves, meaning the valve stem needs to turn only 90° for the valve to fully open or close. With mechanical lever actuation (pneumatic and electrical actuation are also possible), the valve’s lever is turned 90° to accomplish this. When turned on, the opening in the plug is in line with the ports, and media can flow through the valve. Closing the valve rotates the plug, so the opening is no longer aligned with the ports, and the plug’s body blocks the flow.

    Gate valves are multi-turn valves, meaning the valve stem needs to turn more than 360° for the valve to fully open or close. Therefore, a gate valve closes significantly slower than a plug valve. Turning the valve’s handwheel (mechanical actuation) can raise or lower the disc within the valve’s body. Fully raising the disc allows media to flow unobstructed, and fully lowering the disc blocks the media. Discover more by reading our gate valve and plug valve articles!

    Plug valve design

    Plug valveFigure 2: Plug valve

    The four distinguishing design characteristics of a plug valve are the plug shape, plug opening, whether the valve is lubricated or non-lubricated, and the number of ports.

    Plug shape

    • Cylindrical: This shape allows for a larger opening but has a shorter life span.
    • Tapered: This shape has a restricted opening but typically lasts longer.

    Plug opening

    • Rectangular: This opening is the most common; the size of the opening is at least 70% of the connecting pipe’s inner diameter.
    • Round: This opening can be full-bore or reduced-bore design.
    • Diamond: This opening has a venturi restricted flow type and is designed for throttling flow.

    Lubricated vs non-lubricated

    • Lubricated: The valve’s parts are entirely metal. Lubrication reduces friction between the plug and valve body, acts as a seal, and prevents corrosion.
      • Before lubricating a plug valve, consult the plug valve’s manufacturer to determine the correct lubricant to use.
    • Non-lubricated: A Teflon or plastic sleeve fits around a tapered plug, which presses the sleeve against the valve body for better sealing. Non-lubricated plug valves require minimal maintenance and are unsuitable for high-temperature applications.

    Ports

    • Double-port: A standard, bidirectional design used as a full-bore or reduced-bore valve.
    • Multiport: 3-way plug valves are common, but 4-way and 5-way are also possible. Multiport plug valves are used in transfer lines and diverting services. A single multiport plug valve can take the place of multiple gate valves.

    Gate valve design

    Beyond how to actuate a gate valve (mechanically, pneumatically, or electrically), the primary distinguishing design characteristics are the valve’s disc, how the bonnet connects to the valve body, and whether the stem is rising or non-rising.

    Disc types

    • Wedge: This type has a high wedging force which assists with sealing due to its wedge shape that sits on two inclined seats.
    • Knife: This type can cut through thick fluids and dry solids that build up using its beveled edge.
    • Double-disc: This type uses two discs that expand from one another to give a tight seal.
    • Slab: This type is one piece with a hole bored through it. The hole aligns with the ports, allowing flow, when the gate is fully open and the disc body blocks flow through the ports when the gate is fully closed.

    Bonnet types

    • Welded: This type is less likely to leak because it is threaded into the valve body and the body-bonnet joint is welded.
    • Bolted: This type is suitable for high-pressure and large valve size applications.
    • Screwed: Normally used in small size valves, this is the simplest type of bonnet construction.
    • Pressure sealed: As pressure within the valve increases, the body-bonnet joint seal increases. This type is used typically for high-pressure applications above 100 bar.

    Rising vs non-rising stem

    • Rising stem: The stem moves up or down as the valve opens or closes.
    • Non-rising stem: The stem remains within the valve as the valve opens or closes.

    Advantages vs disadvantages chart

    There are many materials available for plug and gate valves, so finding the right material for an application is possible. Learn more by reading our chemical resistance guide!

    Tbale 1: Plug valve vs gate valve

    Plug valve Gate valve
    Installation space Requires less space but has a long handle relative to valve size that must be considered Requires more space, particularly space above for rising stem valves
    Response time Quarter-turn valve, faster Multi-turn valve, slower
    Operation frequency Designed for more cycles Designed for infrequent cycles
    Leakage Can provide a bubble-tight shutoff Strong sealing capabilities except for low-pressure systems
    Corrosion/Wear Less corrosion and wear on the stem because it doesn’t sit in the flow path. May cause water hammer if incorrectly operated. The stem sits in the flow path and will experience more corrosion and wear
    Pressure Excellent design for low-pressure systems More suitable for high-pressure systems and may leak if used in low-pressure systems
    Temperature Lubricated plug valves are more suitable for high-temperature applications than non-lubricated plug valves Suitable for higher temperature systems but check with the manufacturer as too high of temperatures may warp the valve body, which will cause the disc and seats to become unaligned
    Flow control Provides on/off functionality and diamond opening plug valves can throttle flow Can only provide on/off functionality. Throttling flow will damage the valve.
    Flow restriction/Pressure drop Plug valves with restricted openings cause some pressure drop, full-bore plug valves are available Full-bore valve, pressure drop is insignificant
    Flow capacity Lower Higher
    Flow direction Bidirectional and multiport Bidirectional
    Power requirement Higher under high pressure Lower under high pressure
    Torque High, especially under high pressure Low

    FAQs

    Is a plug valve full bore?

    A plug valve’s plug opening can be full bore but is also available in reduced flow for applications where pressure drop is not a large concern.

    What is the difference between a gate valve and a plug valve?

    A big difference between a gate and plug valve is that a gate valve is multiturn, and a plug valve is quarter-turn. So a plug valve can be opened or closed faster than a gate valve.

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