Root cause analysis of the fatigue failures of the pulsation dampers of a large underground gas storage (UGS) system

Two large identical 6-cylinder Ariel JGB/6 reciprocating compressors each of 7.5 MW, are used for an underground gas storage system (UGS) plant of RWE Gasspeicher GmbH located in Epe, Germany. The system is in operation since 2005. In 2011 several internals parts (baffle plates and baffle choke tubes) of the pulsation dampers were broken. TNO has carried out a Root Cause Analysis (RCA) and it was shown that the failures were caused by a combination of bad manufactured welds, too high thermal (cyclic) stresses caused by heating up and cooling down the system several times a day and by too high dynamic stresses caused by vibrations. The paper will give a detailed overview of the RCA and the proposed measures to avoid these failures.