Quick Overview:
- Check valve selection for specific industries — oil and gas, water treatment, HVAC, chemical processing and fire suppression — requires matching the valve design to the specific fluid, temperature, pressure, debris content and operational cycling requirements of each application.
- API 6D covers check valves for pipeline service in oil and gas; API 594 covers wafer and lug check valves; BS EN 12334 covers industrial check valves for general service; and BS EN 13959 covers check valves for water supply — using the right standard ensures the valve meets the industry-specific requirements.
- Fire suppression check valves and backflow prevention check valves have additional requirements beyond standard industrial service — approvals from FM Global, UL or LPCB are mandatory for fire system service, and WRAS approval is mandatory for potable water backflow prevention.
Check Valves Across Industries: Application-Specific Selection Guide
A check valve is a check valve — until you look at what it is actually doing, and then you realise that the check valve on a borehole pump discharge in a rural water supply, the check valve on a crude oil pipeline pig receiver, and the check valve in a fire suppression deluge system are three fundamentally different products serving fundamentally different purposes in fundamentally different environments. The selection process for each is different, the applicable standard is different, and the maintenance requirements are different. Here is how to navigate that landscape.
Oil and Gas Pipeline Service — API 6D and API 594
Check valves in oil and gas pipeline service must comply with API 6D (Specification for Pipeline and Piping Valves) for mainline applications, or API 594 (Check Valves: Flanged, Lug, Wafer, and Butt-Welding) for plant and process check valves. API 6D sets requirements for materials (generally ASTM A105/A216/A352 for carbon steel, with NACE MR0175/ISO 15156 compliance for sour service), testing (API 598 hydrostatic and seat leakage tests), and documentation (material test reports, dimensional inspection, traceability marking).
Pig-compatible check valves are a specific requirement in pig-launched pipeline systems. A standard swing check with an internal disc pivot arm protruding into the bore will catch and trap a pipeline pig, causing a pig loss and a major pipeline retrieval operation. Pig-compatible check valves have a clear, unobstructed bore when open — they use a full-bore swing disc that retracts fully into the body, or a ball check where the ball is retained in a cage clear of the bore. This is a design specification that must be explicitly called up in the purchase enquiry; do not assume a standard check valve is pig-compatible.
Sour service in oil and gas introduces the hydrogen sulphide stress corrosion cracking (SSCC) risk. Carbon steel components exposed to H2S-containing fluids under tensile stress can crack suddenly at stress levels well below the normal yield strength. NACE MR0175/ISO 15156 restricts the hardness of all wetted metallic components to HRC 22 or below (for standard carbon steels), which limits the range of hardfacing materials that can be used on seat faces and excludes some high-strength bolt materials. Verify NACE compliance for every component in the wetted path when specifying check valves for sour service.
Water Treatment and Distribution
Check valves in water supply must comply with BS EN 13959 (Check valves DN 6 to DN 250 — Flanged and wafer check valves for potable, non-potable water and sewage) and carry WRAS approval for potable water applications. The WRAS approval confirms that all materials in contact with the drinking water — body, seat, disc, seals, lubricants — have been tested and are confirmed not to impart taste, odour or harmful substances to the water. Using a non-WRAS-approved check valve in a potable water supply is a regulatory non-compliance; water companies will insist on replacement.
In water distribution, check valves must also be compatible with water network flushing velocities. During mains flushing, flow velocities of 1.5 to 2.5 m/s are routinely achieved in distribution mains, and the check valve must open fully at these velocities without generating unacceptable pressure drop that would prevent the hydraulic flushing gradients being achieved. Verify the pressure drop characteristic at maximum flushing velocity as well as at design flow.
Sewage check valves require special consideration for the solids-handling requirement. Flat-face swing check valves with smooth internal surfaces and no internal protrusions are preferred; dual plate check valves with their internal spring and hinge pin are generally not suitable for raw sewage service. Non-slam designs are important on sewage rising mains where slam-induced pressure pulses can rupture old clay or concrete sewer pipes, which have limited ability to withstand transient pressures beyond their static working pressure.
HVAC and Building Services
Heating and chilled water systems use check valves to prevent reverse thermosiphoning through standby pumps, to protect heat exchangers from reverse pressure during maintenance, and to prevent backflow through three-way valve bypass circuits. The key selection criteria in HVAC are low pressure drop (to minimise pump energy), quiet operation (noise propagation through building structure is a significant concern), and compatibility with glycol antifreeze solutions in chilled water systems.
Silent check valves — spring-assisted lift designs that close before reverse flow establishes — are widely used in HVAC because their controlled closure prevents the valve slam that would create noise complaints in occupied buildings. The spring force must be sized to close the disc against the maximum system backpressure (pump discharge head) but not so strong that it creates excessive pressure drop at normal flow. HVAC check valve manufacturers publish the spring force options for each valve size; select the appropriate spring based on the pump shut-off head.
Chemical Processing
Chemical process check valves face the widest range of material compatibility challenges. Aggressive acids (sulphuric, hydrochloric, nitric), bases (caustic soda, ammonia), solvents and oxidising agents require specific body and seal materials that go beyond the standard bronze and EPDM of general service valves. PTFE-lined check valves — with a full internal PTFE lining and PTFE or FKM (Viton) seals — handle the majority of aggressive chemical service applications. All-polypropylene or PVDF (polyvinylidene fluoride) check valves are used in concentrated hydrofluoric acid and some oxidising acid services where even PTFE fails.
Check valve selection for chemical service always begins with a chemical compatibility table lookup — matching the process fluid, concentration, and temperature against the published resistance data for the candidate body and seal materials. This is not optional: a check valve seal material that is rated “borderline” at ambient temperature in a mild concentration of the process chemical will fail rapidly at elevated temperature or higher concentration.
Fire Suppression Systems
Check valves in fire suppression systems — sprinkler systems, deluge systems, foam systems — carry the added burden of life-safety certification. Every check valve installed in a fire suppression system must be approved by one or more of the recognised fire safety certification bodies: FM Global (Factory Mutual), UL (Underwriters Laboratories) or LPCB (Loss Prevention Certification Board). These approvals confirm that the valve has been tested to specific operational performance standards and will function reliably after extended periods of standby — potentially years — during which the valve may not have been operated at all.
The specific check valve in a wet sprinkler system is the alarm check valve — a swing check valve with an alarm port that connects to the water flow alarm and pressure switch. When the disc lifts in response to a sprinkler head operating, water flows through the alarm port and triggers the alarm signal. The alarm check valve must therefore maintain a reliable dry seat for years of standby, open reliably at the low differential pressure of the first sprinkler head activating, and seal against reverse flow when the system is restored after use.
Conclusion
Check valve selection is never generic — it is always application-specific. The fluid, the industry, the standard, the certification requirement and the operational duty all combine to define the correct product. Treat check valve specification as seriously as you would treat a control valve selection, verify the minimum flow requirements and closure behaviour against the actual system, and confirm the applicable approval or standard for the industry context. Do those things and the check valve will silently and reliably perform its single function for the life of the installation.