Fire on a compressor of a desulphurisation unit

In a hydrodesulphurisation unit of a refinery, an operator which was performing a control tour heard noises and clicks on the hydrogen compressor and stopped it.
The compressor was of a reciprocating compressor with 2 opposite cylinders and 1 stage, operating at 60 bar. When the compressor was stopped, the cylinder broke and released hydrogen-rich gas that ignited 15 to 20 seconds later.
The suction separator tank was equipped with 2 level alarms, one of which was coupled with the safety emergency stop. Their good functioning had been tested and should have excluded the massive arrival of liquid. No precursors could be found in the control room. Oil was found in the discharge manifold and a presence of greasy deposits on the outer face of the piston and on the bottom of the cylinder. In addition, the valves were heavily fouled and the suction filter partially clogged with deposits. Non-compliance with procedures was one of the components causing the accident.

The INITIATING CAUSE was clogging of the internal piping due to deposits.
ROOT CAUSE was the lack of effective maintenance and inspection. Non-compliance with procedures was one of the components causing the accident.

hydrogen compressor

an operator heard noises and clicks on the hydrogen compressor and stopped it.

Oil was found in the discharge manifold and a presence of greasy deposits on the outer face of the piston and on the bottom of the cylinder. In addition, the valves were heavily fouled and the suction filter partially clogged with deposits.

The operator stopped the compressor.

The suction separator tank was equipped with 2 level alarms, one of which was coupled with emergency stop. However, this did not worked.