Control valve pressure test

 

Introduction

For proper working of control valves there are some tests .they are commonly called as control valve pressure test.There are 3 types of Control valve pressure tests

  1. Body test

  • For body test blind the output of control valve using blind flange
  • Valve should be fully opened position either control valve is NO or NC. It should be open at the time of test.
  • The other important parameter to check is body rating of control valve.

Body rating is the amount of total pressure which the body and stem seal can withstand without leaking.

  • If the body rating is 300 psi
  • The pressure of water that should give through inlet of control valve is 300  * 1.5 = 450 psi
  • With the help of pump produce 450 psi in the control valve and with the help of master gauge we can make sure that pressure is 450 psi
  • Then close the mechanical valve.
  • Check whether any leakage of water through outlet of control valve.
  • If there is no leakage the body test is passed.

 

  1. Seat leakage test(flow test)

  • For flow test outlet of the control valve should be open
  • The valve should be fully closed
  • The procedure is same as body test
  • Apply 450 psi to the valve and check for any leakage.
  • If there is leakage i.e. due to trim damage, seat ring damage, actuator and valve stem are not properly connected and aligned.

  1. Function test

  • Check whether the valve is properly assembled.
  • The valve, i/p converter, current generator, and instrument air supply are set up.
  • Instrument air supply Is checked. It is set according to the i/p converter requirements
  • 4 ma current signal is applied to the i/p converter the valve stem shall be in 0% travel
  • When 20 ma is applied 100% travel should be done
  • If the valve stem travel indication didn’t show correctly then calibration is to done.
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