7 Key Factors Influencing the Selection of Check Valve Types in Petrochemical Applications

This is the most fundamental and critical factor.

• Corrosiveness: Whether the medium is corrosive (e.g., sulfur-containing crude oil, acidic gases, strong alkalis) determines the material selection for key components such as the valve body, valve disc, and seal rings. For instance, corrosion-resistant alloys like stainless steel, Monel, Hastelloy, or even titanium must be selected.
• Viscosity and Cleanliness: For high-viscosity media (e.g., heavy oil, asphalt) or media containing solid particles and prone to scaling (e.g., residual oil, slurry), choose check valves with unobstructed flow paths that resist jamming, such as swing-type, ball-type, or non-wear types. Wafer-type double-disc or lift-type valves are unsuitable as they are prone to jamming.
• Toxicity and Hazardous Properties: For highly toxic, flammable, or explosive media, check valves must exhibit zero leakage or extremely low leakage characteristics. Metal-to-metal sealed check valves are typically selected, or in special cases, valves with grease injection systems may be employed.

• Steady Flow:Suitable for most check valves.
• Low Flow or Fluctuating Flow: Requires valves that open and seal sensitively at low velocities, such as wafer-type double-disc check valves due to their lightweight discs and rapid response.
• High Flow Velocity: Swing check valves and axial flow check valves better accommodate high flow velocity conditions while offering lower pressure drop.

• Working Pressure Rating: Directly determines the valve's pressure class (e.g., Class 150, 300, 600).
• Minimum Opening Pressure: Lift check valves require a certain back pressure to seal, while swing and wafer types require lower opening pressures.
• System Pressure Fluctuations: In systems with frequent pressure fluctuations, select types that operate stably to prevent valve disc “chattering” and premature wear.

• Lift Check Valves: Typically only installable on horizontal pipes, requiring the valve disc axis to be perpendicular to the horizontal plane.
• Swing Check Valves: Installable on horizontal or vertical pipes (when installed vertically, the medium must flow from bottom to top).
• Wafer Check Valves: Flexible installation orientation, but medium flow direction must still be considered.

• Wafer-type check valves: Shortest structural length, highly space-efficient, lightweight.
• Swing-type check valves: Longer structural length, requiring greater installation space.
• Lift-type check valves: Higher structural height.

This is a critical factor in preventing water hammer phenomena.

• Quick-closing Type: Such as wafer-type double-disc or swash plate check valves, which close rapidly to effectively prevent significant reverse flow of the medium. However, excessively fast closing may trigger direct water hammer.
• Slow-closing/Controlled-closing Type: Examples include swing check valves with dampers or buffer mechanisms, and axial flow check valves. These achieve a two-stage closing process—rapid initial closure followed by controlled deceleration—via hydraulic or counterweight systems. This significantly reduces pressure peaks (water hammer) during closure, making them ideal for critical locations like pump outlets.

• Swing, axial flow, ball, and Y-type lift check valves feature unobstructed flow paths with minimal pressure drop. (Low-resistance types). 
• High-resistance types: Traditional lift check valves exhibit relatively high pressure drop due to tortuous flow paths.

The petrochemical industry adheres to stringent specifications and standards; valve selection must comply with project requirements.

• International/Industry Standards: e.g., API 594 (wafer and double-flanged check valves), API 6D (pipeline valves), ASME B16.34 (valve flange ends, butt-weld ends). These standards define valve construction, pressure-temperature ratings, and testing/inspection requirements.
• Fire Safety Standards: Examples include API 607/ISO 10497, which require valves to maintain seal integrity for a specified duration during fire conditions. This is typically achieved through specialized soft-seal designs and metal-to-metal auxiliary sealing mechanisms.

• Initial Purchase Cost: Wafer-type check valves typically offer the lowest cost, while those with special features (e.g., slow-closing) or special materials incur higher costs.
• Installation and Maintenance Costs: Wafer-type check valves feature simple installation but require disassembly of bolts on both flanges during maintenance. Double-flanged (swing check) valves are heavier and demand robust mounting supports, but their openable bonnet facilitates in-service internal component maintenance.
• Operating and Energy Costs:Low-flow-resistance valves reduce pumping energy consumption, yielding significant long-term electricity savings.
• Reliability and Lifespan: Selecting valves suited to operating conditions substantially minimizes failure downtime and repair/replacement expenses. Over the entire lifecycle, such valves may prove more cost-effective than initially cheaper alternatives.