Valve
Troubleshooting

A gate valve that passes fluid through in the closed position has a seat or wedge sealing failure.

Leakage from the valve stem area (stuffing box or gland packing) is one of the most common maintenance issues on gate valves.

Excessive handwheel torque on a gate valve makes manual operation unsafe and can indicate imminent mechanical failure.

Gate valves operated in a partially open position vibrate and produce noise, causing rapid wear of the wedge and seating faces.

A ball valve passing fluid in the closed position has worn, damaged, or chemically degraded seats.

A ball valve requiring excessive operating force may fail to open or close when needed, which is particularly dangerous for emergency shutdown (ESD) valves.

Leakage past a closed butterfly valve disc occurs when the disc-to-seat contact is broken by wear, deformation, or chemical attack.

Butterfly valve discs vibrate at certain partial-open positions due to vortex shedding from the disc edges.

Check valve chatter (rapid, repeated opening and closing of the disc) causes severe impact damage to the disc, seat, and hinge pin, and can cause piping fatigue.

Water hammer after pump shutdown occurs when a swing check valve closes slowly, allowing significant flow reversal before disc contact.

A check valve that allows reverse flow in the closed position defeats its purpose as a non-return device.

Globe valve seat leakage is typically caused by wire-drawing erosion - a high-velocity groove eroded through the seat face when the valve is operated at a partial opening for extended periods.

A safety valve that leaks continuously at operating pressure is 'simmering' - a critical issue that wastes product, accelerates seat erosion, and can cause the valve to be damaged by the time it needs to relieve.

A safety valve that fails to open at or below its certified set pressure is a critical safety system failure.

Diaphragm failure is the primary failure mode for diaphragm valves.

An actuated valve that does not move when a control signal is received can have causes in the signal path, the actuator power supply, the solenoid valve, or the mechanical linkage.

A control valve that oscillates continuously around a setpoint (hunting) wastes control response, causes rapid seat wear, and creates cyclic loading on the process.

Valves requiring high operating torque — large gate valves, high-pressure butterfly valves, and large ball valves — are fitted with a manual gearbox (bevel gear operator or spur gear operator) to multiply the handwheel force.

A blocked strainer screen is a normal maintenance event but if not detected promptly, the increasing differential pressure across the strainer can collapse the screen, sending accumulated debris downstream into the equipment it was protecting.

Flange joint leakage at a valve is one of the most common maintenance issues in industrial plants.

Stem packing leakage is the most common valve maintenance issue across all valve types.

Cavitation occurs when pressure within the valve drops below the liquid's vapour pressure, forming vapour bubbles that collapse violently as pressure recovers downstream.

Valves that have not been operated for months or years can seize due to corrosion, product build-up, or packing dry-out.

A valve failing its LDAR (Leak Detection and Repair) survey has detectable volatile organic compound (VOC) or methane emissions above the regulated threshold (typically 500 ppm for EPA Method 21, or 10,000 ppm for the 'leaker' definition).

Flashing occurs when liquid pressure drops below its vapour pressure across the valve and remains below it downstream — the fluid converts to vapour and stays as vapour.

Valve sizing errors are one of the most common causes of process control instability, noise, vibration, cavitation, and premature trim wear.

Thermal locking (also called heat seizure or thermal bind) occurs when a valve becomes impossible to operate due to differential thermal expansion between the valve body, trim, and stem components at elevated temperature.

Valves in cryogenic service (LNG, liquid nitrogen, liquid oxygen, liquid argon, liquid CO2) operate at temperatures from -40 degrees C down to -196 degrees C.

Slurry erosion is the mechanical removal of valve material by solid particles suspended in the process fluid.

Pressure seal bonnet valves (gate and globe, Class 900 through 2500) use the process pressure itself to energise the seal between the bonnet and body — unlike bolted bonnet valves which rely on bolt load alone.