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.

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.

(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