MS-FGAS 005/A METHOD STATEMENT

MS No: 005 A Issue: Generic 2
F Gas Test Rigs: ……………. Name: …………………… /
ThornliebankInd Estate, Glasgow G46 8JW
Tel: 0141 638 7916 Fax: 0141 638 8111
e-mail:
OFN Tightness Pressure Testing of F Gas Test Rigs (Braze Test Piece and Test Rig
previously strength tested) / Candidate to initial each step as the test progresses
Assessment 2: / Tightness Test of F Gas Rig / Pressure Source: / OFN Package
Date:
1. / Tie red/white tape to warn staff and third parties the equipment is pressurised (GS4 27(b)).
2. / Place “no entry” signs at all entrances to the test area.
3. / Personal Protective Equipment shall be worn (RA-FGAS001).
4. / Check pressure in the pressure source. Fit correct regulator and gauge test set supplied for F Gas test. Note 0-50.0 Bar (G) outlet regulator supplied.
5. / NEVER LEAVE THE PRESSURE SOURCE UNATTENDED WHILE CONNECTED.
6. / The immediate test area shall be evacuated and personnel moved to locations behind a brick wall or similar with no line of sight to the Test Rig while it is being tightness tested.
7. / Ensure a pressure test relief valve (pre-set to 27.6 bar) is fitted on the HP Receiver and a pressure test relief valve (pre-set to 16.2 or 17.2 Bar) is fitted on the compressor body on the suction side. (Assessor to explain to candidates that system normal relief valve is set to 24.8 Bar and that the 27.6 Bar and 16.2 or 17.2 Bar relief valves are fitted for safety reasons).
8. / Close compressor Suction, Discharge and Oil Return stop valves to isolate the compressor during the tightness test.
9. / Check all flare and compression type fittings for tightness.
10. / All valves to be checked and placed open to ensure entire pressure envelope is tested. Note: The liquid solenoid will require a magnetic coil to open the valve.
11. / Connect the charging line at the appropriate places on system and secure the charging line at BOTH ends in case it blows off.
12. / Determine what 10% of the design allowable pressure is and set the regulator outlet pressure to not more than 5 Bar (G) above this. Then slowly pressurise the equipment (GS4 27d) to 10% of the allowable pressure.
13. / At 10% of the design allowable pressure isolate the pressure at the regulator.
14. / Reduce the pressure by 0.5 Bar (G).
15. / Enter the cordoned off area and check aurally for leaks. If necessary carry out a soapy bubble test to identify the source of a leak.
16. / If a leak is identified vent the OFN to reduce the pressure in the rig back to atmospheric. When the leak has been repaired leave the cordoned off area (GS4 29).
17. / Do not attempt to tighten anything whilst leaking part is pressurised (GS4 31).
18. / Set the regulator outlet pressure to not more than 5 Bar (G)above the tightness test pressure then slowly pressurise the equipment. The pressure shall be applied gradually increased by steps of approximately 10% until the required tightness test pressure is reached (GS4 27d).
19. / Once tightness test pressure is reached enter cordoned off area (GS4 24 (a)) and carry out a soapy bubble leak test. If a leak is found then the entire system shall be vented and the leak repaired. The section can then be pressurised to the tightness test pressure to confirm the leak has been repaired. There is no need to strength test again.
20. / Vent the pressure in the system to atmosphere slowly and remove the charging line (GS4 29).
21. / Ensure there are no trapped pressures in the system, e.g. check valves (GS4 28).
22. / Remove the red/white tape.
23. / Open the compressor Suction, Discharge and Oil Return isolating valves.
24. / Complete tightness test pressure record.

GS4 refers to HSE Guidance Note – Safety in Pressure Testing

RA-FGAS001 refers to Star Refrigeration Risk Assessment for Strength & Tightness Pressure Testing