Check Valves For Oil & Gas Applications
Figure 1: Check valves are used throughout offshore drilling platforms to prevent contamination and dangerous situations.
Check valves in oil and gas systems mitigate backflow, preventing dangerous problems like leaks, fires, explosions, contamination, and shutdowns. The check valve opens when the gas or oil pressure reaches the valve's cracking pressure and closes when the pressure drops or backflow occurs. This article covers common considerations when selecting a check valve for oil or gas media.
Table of contents
- Common check valve applications in oil and gas systems
- Types of check valves used in oil and gas
- Materials
- Installation considerations
- FAQs
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Common check valve applications in oil and gas systems
- Subsea pipelines: Check valves are installed to prevent seawater from returning to the pipeline, which could cause contamination or corrosion.
- Wellhead assemblies: Used to prevent the backflow of oil or gas from the wellbore, ensuring safe and controlled extraction.
- Gas lift systems: Check valves are used to control the injection of gas into the well, preventing the backflow of oil or gas into the gas lift lines.
- Pump discharge lines: Installed to prevent the reverse flow of media back into the pump, protecting it from damage.
- Storage tanks: Check valves prevent the backflow of oil or gas into the supply lines, ensuring safe storage conditions.
Types of check valves used in oil and gas
Each type of check valve commonly used in the oil and gas industry has its own advantages:
- Swing check valves: These valves have a disc that swings on a hinge to block reverse flow. They are suitable for low-pressure applications (up to 16 bar or 232 psi) and provide minimal resistance to flow.
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Spring-loaded check valves: These valves use a spring to help close the valve quickly, preventing backflow. They are suitable for applications requiring fast response and can be installed in any orientation. They are ideal for high-pressure applications (up to 63 bar or 914 psi).
- Read the standard MSS SP-126 for more information on typical characteristics of spring-loaded check valves in oil and gas applications.
- Y-shape check valves: These valves have a Y-shaped body that allows for a streamlined flow path, reducing pressure drop across the valve. The disc is mounted at an angle and lifts to enable flow, returning to the seat to prevent backflow. They are ideal for high-pressure applications (up to 40 bar or 580 psi).
Figure 2: Common check valve types in oil and gas applications: spring-loaded (left), y-shape (middle), and swing (right).
Table 1: Comparison of Different Check Valves
| Feature/Criteria | Lift check valves | Swing check valves | Spring-loaded check valves | Ball check valves | Y-shape check valves | Sanitary check valves |
|---|---|---|---|---|---|---|
| Operation | Disc lifted by fluid flow, closes by gravity or back pressure | Hinged disc swings open with flow, closes when flow reverses | Spring mechanism compresses to open, expands to close | Ball moves away from seat to allow flow, returns to seat to block reverse flow | Y-shaped body with disc | Designed for hygienic applications, often with a spring-loaded disc |
| Advantages | Good sealing for high-pressure applications | Low pressure drop Suitable for fluids with suspended solids | Fast response to flow changes Can be installed in any orientation | Simple design, reliable operation Can handle viscous fluids | Compact design Low pressure drop | Easy to clean Suitable for food and pharmaceutical industries |
| Limitations | Lift check valve pressure drop is higher due to disc lifting Limited to horizontal installation Sensitive to debris, which can obstruct disc movement | Generally limited to horizontal installation Slower response, allowing potential backflow before sealing | Higher cost due to spring mechanism Potential for spring wear in high-cycling applications | May not seal well with low back pressure Limited to certain orientations | Not suitable for high-pressure applications Limited to specific flow conditions | Higher cost Requires regular maintenance to ensure hygiene |
| Ideal applications | Clean fluid systems with consistent flow | Water and wastewater systems with large volumes and suspended solids | Systems requiring quick response and versatile installation | Pumping systems, wastewater applications | Low-pressure steam and gas systems | Food, beverage, and pharmaceutical processing |
| Installation flexibility | Limited (horizontal only) | Limited (primarily horizontal) | High (any orientation) | Moderate (depends on design) | Moderate (depends on design) | High (often designed for easy disassembly) |
| Cost | Moderate | Low | Higher | Low to moderate | Moderate | Higher |
| Maintenance | Low to moderate, depending on debris exposure | Low | Moderate to high, due to potential spring wear | Low | Low to moderate | Moderate to high, due to hygiene requirements |
Materials
Check valves for oil and gas applications are typically made from durable materials to withstand harsh conditions. Common materials include:
-
Stainless steel: Known for its corrosion resistance and strength, stainless steel is ideal for high-pressure and high-temperature applications.
- MSS SP-42 has more information on stainless steel check valves with flanged ends and their application in oil and gas systems.
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Brass: While not as strong as stainless steel, brass is often used in lower-pressure applications due to its good corrosion resistance and cost-effectiveness.
- BS 5154:1991 contains more information about copper-alloy check valves, including brass check valves.
Figure 3: A stainless steel 316 check valve (left) and brass check valve (right).
Seal materials
For most valves, the seal material controls the valve's operating pressure and temperature more than the body material. This is due to the seal typically degrading at lower pressures and temperatures than the metal body. For oil and gas applications, seals must be robust and are often made of the following materials:
- FKM
- Teflon
The recommended maximum temperature for these materials is approximately 200 °C (392 °F). Teflon handles higher pressures than FKM.
Installation considerations
Proper installation is crucial for the effective operation of check valves. Consider the following:
- Orientation: Install the valve in the correct orientation to ensure proper flow direction.
- Accessibility for maintenance: Position the valve where it can be easily accessed for inspection and maintenance.
- Compatibility: Ensure the check valve material is compatible with the system's fluid to prevent corrosion or damage.
- Pressure and temperature ratings: Verify that the valve is suitable for the system's pressure and temperature conditions.
- Pipe alignment: Ensure proper alignment of the pipes to avoid stress on the valve, which can lead to leaks or failure.
Read our check valve installation guide for check valves to learn more.
FAQs
How do check valves work in oil and gas systems?
Check valves in oil and gas systems use a disc or ball that opens with forward flow and closes against reverse flow, preventing backflow.
What materials are used for check valves in oil and gas?
Check valves in oil and gas are made from materials like stainless steel, carbon steel, and alloys to withstand harsh conditions and corrosive fluids.
