Pressure Tests
Shell Test:
o Involves subjecting the entire valve body to hydrostatic or pneumatic pressure.
o Typically performed at 1.5 times the valve's rated pressure.
o Aims to verify the structural integrity of the valve body.
Seat Test:
o Focuses on the sealing surfaces of the valve.
o Involves applying hydrostatic or pneumatic pressure to the closed valve.
o Checks for leakage across the valve seat.
Functional Tests
Operation Test:
o Evaluate the valve's ability to open and close fully and smoothly.
o Includes checking for stiction, binding, or excessive torque.
Leakage Test:
o Determines the leakage rate through the valve seat, stem, and packing.
o It can be performed using various methods, including bubble testing, helium mass spectrometry, or pressure decay.
o Includes cavity valve test (CVT).