Admiral Valve Repair And Supply

Safety Relief Valve Pointers

 

1.  ASME Codes require that valves for air, steam and water service over 140 deg F. have test levers.

2.  Steam safety valves may be used for air service, but not vice versa.  Liquid valves should only be used on liquid service.

3.  Safety relief valves should be installed vertically with the drain holes open or piped to a convenient location.

4.  The inlet to and outlet from a safety relief valve must be at least as large as the inlet and outlet connections of the pressure relief valve.

 

Maintenance

Per the National Board RB-8010

Inspection areas of concern include:

A.  Safety considerations

B.  Device data

C.  Condition of the device

D.  Condition of the installation

E.  Testing and operational inspection.  

Per the National Board RB-8210

Check for evidence that the valve or device is leaking or not sealing properly.  Seals for adjustments should be intact and show no evidence of tampering.  Connecting bolting should be tight and all bolts intact.  The valves should be examined for deposits or material build up.  Evidence of rust or corrosion should be checked.  Check for damaged or misapplied parts. If a drain hole is visible, ensure it is not clogged with debris or deposits.  Check for test gags left in place after pressure testing of the unit.  Bellow valves shall be checked to ensure the bonnet vent is open or piped to a safe location.  The vent shall not be plugged since this will cause the valve set pressure to be high if the bellows develops a leak.  Leakage noted from the vent indicates the bellows is damaged and will no longer protect the valve from the effects of back pressure. 

Per the National Board RB-8300

Inspect the inlet piping and ensure that the pipe size is not smaller than the device inlet size.  Inspect the discharge piping and ensure that the discharge pipe size in not smaller than the device outlet size.  Check that the valve drain piping is open.  Check drainage of discharge piping.  Check that the inlet and discharge piping are not binding or placing excessive stress on the valve body which can lead to distortion of the valve body and leakage or malfunction.  Check that there are no intervening isolation valves between the pressure source and the valve inlet or between the valve outlet and its point of discharge (unless otherwise permitted) 

Per the National Board RB-8410

Recommended Inspection and Test Frequencies:

Power Boilers

A.  Pressure less that 400 psig: Manually check every 6 months; pressure test annually to verify nameplate set pressure or as determined by operating experience as verified by testing history.

B.  Pressure greater than 400 psig: Pressure test to verify nameplate set pressure every three years or as determined by operating experience as verified by testing history.  Pressure tests should be performed prior to bringing the boiler down for planned internal inspection so needed repairs or adjustments can be made while the boiler is down.

High Temperature Hot Water Boilers

A.  Pressure test annually to verify nameplate set pressure or as determined by operating experience as verified by testing history.  For safety reasons, removal and testing on a steam test bench is recommended.  Such testing will avoid damaging the safety valve discharge of a steam water mixture, which could occur if the valve is tested in place.

Low Pressure Steam Heating Boilers

A.  Manual check quarterly; pressure test annually prior to steam heating season to verify nameplate set pressure.

Hot Water Heating Boilers

A.  Manual check quarterly; pressure test annually prior to steam heating season to verify name.

Water Heaters

A.  Manual check every two months.  Due to the relatively low cost of safety valves for this services, it is recommended that a defective valve be replaced with a new valve if a repair or resetting is indicated.

Pressure Vessels and Piping

A.  Frequency of test and inspection of pressure relief devices for pressure vessel and piping service is greatly dependent on the nature of the contents and operation of the system and only general recommendations can be given.  Inspection frequency should be based on previous inspection history.  If valves are found to be defective or damaged by system contents during inspection, intervals should be shortened until acceptable inspection results are obtained.  Where test records and/or inspection history are not available, the following inspection and test frequencies are suggested.