What is Leak Test on board of LPG carrier?

asked 20 Apr '17, 09:37

April 20, 2017, 9:37 a.m.
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Answer:

Leak Test is pre-operation pressure test of the cargo system.

Masters of LPG carriers are advised to deligently carry out pressure test of the cargo system and same to be recorded in the Deck Log book. The check must be done by pressurizing the cargo and vapor system by compressed cargo vapor to working pressure and monitoring the pressure.

There are known cases when LPG carrier was rejected by the terminal in Japan during Leak Test. A minor leak was discovered on a vapour line valve in way of one of the the vapour valve gland. The vessel was not permit by the terminal to perform the cargo operation and immidiately shifted the vessel to the anchorage to do the repairs.

Procedure for pressure testing:

The pipe lines must be pressure tested by the use of cargo compressor. After reaching the testing pressure the compressor has to be stopped and the compressor inlet and outlet valves, cargo vapor line tank inlet and outlet valves to be kept shut. The cargo lines should be pressure tested up to the manifold blanks i.e. manual and ESD manifold valves are kept open during the test.

The system pressure must remain steady for a period of at least 30 minutes . Additionally, the soap solution is to be used on all the flanges, valve body including glands and any other connections on the system. During this soap test there must not be any visible air bubbles. A certificate to this pressure test needs to be issued by the vessel. Many terminals insist that soap test is to be carried out with utmost diligent and recorded in the test certificate.

The above pressure test has to be performed as per below schedule:

  • At six month interval
  • Upon completion of any pipeline repairs on the cargo or vapor system
  • Prior changing of grades to higher pressure cargoes (e.g. propylene and propane)
  • On certain terminal requirement
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answered 20 Apr '17, 09:42

April 20, 2017, 9:42 a.m.
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