Valve Installation and Testing

Valves control the flow of water, gas, chemicals, and sewage in pipework systems on construction sites.
Common types include gate, butterfly, check, ball, and pressure-reducing valves in various sizes.
Large valves weighing over 25 kg require planned lifting using slings, chain blocks, or cranes.
Flange bolts must be tightened in a cross-pattern sequence to the specified torque to prevent leaks.
Pressure testing after installation verifies the valve body and flange connections are leak-free.
PUWER 1998 requires that installed valves are suitable, accessible for maintenance, and properly guarded.
Chemical valves must be compatible with the process fluid — incorrect material causes corrosion and failure.
Valve actuators — electric, pneumatic, or hydraulic — must be isolated before any maintenance work.
Handwheels and operating mechanisms must be accessible and clearly labelled with open and close directions.
As-installed records must document valve type, size, material, location, and test results.

Leak prevention	Incorrectly installed or under-torqued valves leak process fluids causing injury and damage.
Handling risk	Heavy valves require lift plans — manual handling of large valves causes back injuries.
Material compatibility	Wrong valve materials corrode and fail, releasing hazardous fluids.
Operational safety	Poorly labelled or inaccessible valves cause errors during emergency operations.

Do

Don't

Check valve type, size, material, and orientation match the installation drawing.
Use a lift plan for valves too heavy to handle manually — typically over 25 kg.
Tighten flange bolts in a cross-pattern sequence to the specified torque value.
Pressure test the valve and connections before putting the system into service.
Label each valve with its tag number, function, and open/close direction.
Ensure valves are accessible for operation and maintenance after installation.
Isolate actuators before working on powered valve mechanisms.
Record installation details and test results in the commissioning documentation.
Protect installed valves from construction damage until the system is commissioned.
Brief the operations team on valve locations and emergency isolation procedures.

DON'T install a valve in the wrong orientation — check flow direction arrows.
DON'T force valve connections — misalignment indicates pipework issues.
DON'T under-torque or over-torque flange bolts — follow the specification exactly.
DON'T lift heavy valves without a planned lift using rated equipment.
DON'T use valves made from materials incompatible with the process fluid.
DON'T leave valves unlabelled — operators need clear identification in emergencies.
DON'T pressurise the system before completing all valve installation and testing.
DON'T work on powered actuators without confirmed isolation and lock out.
DON'T bury or conceal valves that need to be accessed for maintenance.
DON'T skip the pressure test — leaks at valves cause flooding and contamination.

See also: Pipe Fitting and Flange Safety | Pressure Testing Safety

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