Gate valves are normally used for on-off service and are not recommended for throttling service.
Gate valves are normally installed in horizontal pipe lines with valve stem vertically up.
Flexible wedges are recommended for valves in service above 500° F to avoid wedge binding when the valve is closed when cold, and then heated to operating temperature
Seal weld seats in valves are recommended for high velocity (turbulent) flow or thermal cycling.
After closing a gate valve with sufficient force to develop shut off, the stem should be backed up slightly (1/8 to1/4 turn) to relieve stem load. This will enable the stem to expand slightly without damaging the valves.
Service recommendations for globe valve
Globe valves are normally installed with flow and pressure under the disc. Check the direction of flow on the valve casting. Consult the manufacturer before installing the valve in other direction
For valves equipped with cylinders, electric actuators there may be cost advantage in designing and installing the valves with flow and pressure above the disc.
Conventional globe valves are suitable for throttling applications. Prolonged opening at less than 10% of opening is not recommended due to possibility of excessive vibration, noise and damage of disc and seats. Continuous severe throttling applications may require control valve.
Service recommendations for check valve
Swing check valves are best suited for moderate velocity applications .Either a too low velocity or too high velocity can damage valve internals and shorten valve life. Correct sizing of swing check valves is important.
Service in system involving rapid and frequent flow reversals should be avoided. Locating swing check valve away from elbows, equipments etc, with in the piping system can minimize or eliminate problem.
Swing check valves are normally designed for installation in horizontal pipe runs. Valves may also be installed in vertical runs but flow and pressure under the disc and opening the disc.
Out side lever and weights are effective in preventing slamming of swing check valve in size above 6" NB.
Seal welded seats in valves in service with high velocity (turbulent) flow or thermal cycling recommended.
General recommendation for handling and trouble free operation
End protectors are attached to each valve before shipment. Do not remove the protector until installing the valve.
Valves must be stored in dust free, dry and clean storage room on a proper rubber sheet, wooden crates.
For lifting the valves use proper rope, wire,. Etc through the lifting lugs to avoid damage.
Do not use actuator or valve stem for lifting purpose.
Depressurize and drain the testing fluid in the pipe line before installation.
Before mounting the valves, make sure all foreign objects such as sands or scales are removed by filters or strainers to protect valve seat surface.
Ensure that valve flanges and pipe flanges are coupled with correct alignment.
After mounting the valves, clean the inside of the pipes again so that no weld spatters, chips, scales or sand are left.
For flanged end valves tightening of bolts must be done alternately and diagonally. Provide valve support if required, to reduce pipe stresses.
If leakage is observed from the gland while valve in service, the gland must be retightened immediately. Gland must be tightened just sufficient to stop the leakage. If operating torque is increased after this procedure then it is recommended to replace the packing.
It is recommended to replace the packing during valve maintenance operation. But never replace while valve is being pressurized.
Care to be taken to clean the packing chamber and the valve stem before replacing the packing.
Cast Steel Plug Valves
Compensator Steel Plug Valves (bottom entry) & Lubricated Plug Valves (top entry) comply with the Specifications of API 6-D & API-599.
Mechanical and pressure Balance fixture to avoid jamming of the plug.
Flanged RF or RTJ ends, Threaded ends or Butt Weld ends.
Meets Fire Test in accordance API-6FA.
Flanges in accordance ANSI/ASME B16.5.
Hand-wheel, Impact Hand-wheel, Chain-wheel, Gear operation, Electric, Pneumatic or Hydraulic Actuation as per Customer requirements.