Technical Requirements for Valve Installation

Technical Requirements for Valve Installation

Valves are devices used in fluid systems to control the direction, pressure, and flow of fluids. During the construction process, the quality of valve installation directly affects future normal operation, so it must be given high attention by both construction units and production units.

**Technical Requirements for Valve Installation**

1. **Directionality.** Generally, valve bodies have markings, and the direction indicated by the arrow is the forward flow direction of the gas. Special attention must be paid to avoid incorrect installation. This is because various valves require one-way flow of gas, such as safety valves, pressure reducing valves, check valves, and throttle valves. For globe valves, to facilitate opening and maintenance, gas is also required to pass through the valve seat from bottom to top. However, gate valves and plug valves are not restricted by flow direction during installation.

2. **Installation Position.** Consideration should be given to long-term valve operation and maintenance. The position should be as convenient as possible for operation and maintenance, while also paying attention to the aesthetic appearance of the assembly.

The valve handwheel can be vertically upward, tilted at an angle, or placed horizontally, but the handwheel must not face downward to avoid operating while looking up. Floor-mounted valves should have the handwheel at chest height for easy opening and closing. Non-rising stem gate valves cannot be used underground to prevent stem corrosion.

Some valves have special installation position requirements. For example, pressure reducing valves must be installed upright on horizontal pipelines and must not be tilted. Lift-type check valves require the disc to be vertical. Swing-type check valves require the pin shaft to be horizontal. In summary, the installation position must be determined based on the valve's operating principle; otherwise, the valve may not function effectively or may not work at all.

3. **Installation of Plug Valves.** Verify the model and specifications, inspect for damage, remove sealing covers from threaded ports and excess grease and debris from threads, and test the sealing performance of the plug valve. For gas plug valves, proper force must be applied during installation. Pipe wrenches or spanners of appropriate sizes should be selected based on the plug valve specifications for installation.

4. **Installation of Threaded Valves.** The valve company should ensure that the threads are complete and undamaged. Use a wrench when possible rather than a pipe wrench to avoid damaging the valve body appearance.

5. **Installation of Flanged Valves.** It must be ensured that the two flange faces are parallel to each other and on the same axis. Bolts should be tightened in a crisscross pattern to ensure even force on the valve end faces.

6. **Flanged and threaded valves should be installed in the closed position.** When butt-welding valves to pipelines, the weld root should be welded using argon arc welding to ensure internal cleanliness. During welding, the valve should not be closed to prevent thermal deformation.

7. Generally, valves are directly connected to bellows expansion joints. Therefore, based on the dimensions of the valve, bellows expansion joint, flange, and gasket, the pipelines on both sides should be cut to reserve space for installation.

8. **During valve lifting,** ropes must not be tied to the handwheel or valve stem to prevent damage. Lifting and lowering should be done gently without collision. When placed on supports, the valve should be stabilized and leveled at the required elevation. The valve must have a solid support or bracket underneath to support it. The valve must not be suspended to avoid stress.