Sunday, April 19, 2020

Boiler safety valve setting

  • Take standard pressure gauge (approved by surveyor) for accuracy.  
  •  Fill up water up to ¼ of gauge glass level, and shut main steam stop valve, feed check valve. 
  •  Without compression rings, hoods and easing gears, reassembled the safety valves with  spring compression less than previous setting.  
  • Raise the boiler pressure to desired blow off pressure.  
  • Screw-down spring compression nuts of any lifting valves, until all are quite.  
  • Arrange to have the desired steam pressure  
  • Adjust each valve in turn: 
a. Slacken compression nut until the valve lifts. 
b. Screw-down compression nut sufficiently enough, so that when the valve spindle is
lightly tapped, valve return to its seat and remain seated
c. Measure gap between compression nut and spring casing. 
d. Make a compression ring equal to this gap, and insert under compression nut. 
e. Gag the spindle of this safety valve, to prevent opening, while remaining valve is being
set. 
  • Remaining valve is again set and insert compression ring.  
  • Remove gag and retest both valve to lift and close together.  
  • Cap, cotter and easing gear to be refitted  
  • Caps and cotter pins padlocked to prevent accidentally altering the setting.  
  • When the surveyor satisfied the setting pressure, easing gear should be tested. 
All safety valves set to lift at not greater than 3% above approved working pressure (design
pressure)

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