At our refinery, two nos of Nuovo Pignone (NP) make reciprocating compressors (single stage, two cylinders per stage, double acting type) are installed in H2 service in DHDS plant. Recently, one of the compressors (running) cylinder no.2 discharge valve cover bolts (4 out of 6) came out from the cylinder body on run (while in H2 service) and valve cover got damaged. Upon opening the compressor, no damage to the valve or inside the discharge cylinder was observed and the damage is mainly for the valve cover and the body threads of 5 bolt holes.
The compressor has a spill back system and running at 50% load. While closing the bypass valve of the spill back control valve, the discharge pressure of the compressor has increased from 45.5 to 46.7 Kg/Cm2 g and subsequently the incident has occurred. Set pressure of the safety valve located on the discharge line of the compressor is 49 Kg/Cm2 g. In this regard, request you to share the following:
1. Has anyone similar experience? If so, what were the findings?
2. Can increase of pressure from 45.5 to 46.7 Kg/Cm2 g cause such incident?
3. Can a small explosion be expected between the valve cover and the cylinder body due to some initial small leak?
The compressor has a spill back system and running at 50% load. While closing the bypass valve of the spill back control valve, the discharge pressure of the compressor has increased from 45.5 to 46.7 Kg/Cm2 g and subsequently the incident has occurred. Set pressure of the safety valve located on the discharge line of the compressor is 49 Kg/Cm2 g. In this regard, request you to share the following:
1. Has anyone similar experience? If so, what were the findings?
2. Can increase of pressure from 45.5 to 46.7 Kg/Cm2 g cause such incident?
3. Can a small explosion be expected between the valve cover and the cylinder body due to some initial small leak?