Valve Installation Best Practices for New Plant Commissioning

Pre-Installation Checks

Before installing a valve, verify that the correct valve has arrived against the purchase order, isometric drawing, and valve tag number. Check the pressure class, end connection type, bore size, material certification, and test reports. Remove shipping plugs, protective coatings, and flange protectors. Inspect the valve bore for debris, damage, and correct seat condition. Confirm actuator rotation or travel direction is correct for the designed fail-safe position.

Piping Alignment and Support

• Do not use the valve to pull misaligned pipe flanges together: creates body stress and leakage

• Verify flange face parallelism and concentricity before bolting: maximum gap deviation specified in ASME B16.5

• Install valves with actuator at correct orientation: typically upright but some designs allow horizontal

• Provide independent pipe supports near heavy actuators to prevent bending loads on valve body

• Spring hangers or guides prevent thermal expansion loads from being transferred to valve connections

Flange Bolt Torquing

Flange bolts must be tightened in a star or cross pattern in at least four passes to achieve uniform gasket compression. The final torque values are calculated based on gasket type, bolt material, and flange rating. Under-tightening causes gasket leakage; over-tightening crushes soft gaskets or stretches bolts beyond yield. Torque verification with a calibrated torque wrench is required for Class 600 and above flanged connections.

Commissioning Flush and Testing

• Flush pipelines before valve installation to remove mill scale, weld spatter, and construction debris

• Alternatively, install temporary spool pieces during flushing and install valves after

• Commission valves with instrument air and control signal prior to process introduction

• Stroke all actuated valves full open and full close and verify position indication accuracy

• Confirm fail-safe position on loss of signal or instrument air before process startup

Documentation at Handover

Installation and commissioning records must be collected for each valve: installation torque data, pre-commissioning test results, functional test records, and any deviations or punch list items. These records form part of the plant's as-built documentation and are required for future maintenance, LDAR, and inspection programs. Valve tag numbers must be physically affixed and match the P&ID and asset register.