Mechanical failure of a hydrogen compressor

Discharge pressure of a hydrogen compressor on a chloride plant fell to alarm level without any prior warning. Simultaneously three bumps were heard.
Smoke was seen coming from the hot motor bearing and the machine had to be stopped manuall, because it had not tripped automatically. No external fire occurred and the hydrogen product was directed to the vent stackwhile the chlorine plant continued to run normally.
Examination of the compressor showed that the studs of the driven end first stage cylinder head had failed and subsequent examination of the piston rod showed that this had failed at the threaded attachment to the crosshead, the motor bearing showed severe heating by oil smoke and paint discoloration.

The INITIATING CAUSE was the failure of the compressor piston due to fatigue, under conditions which worsened the consequence.

The post-incident investigation reached the following conclusions:
1. The piston rod failed by fatigue initiated at the crosshead end threads.
2. No evidence was found of any individual error in assembly or operation which contributed directly to the initiation of this incident.
3. Indications are that the vibration trip system was not in function at the time of this piston rod failure, increasing the secondary damage at the motor and resulting in the provision of a possible ignition source for the escaping hydrogen.
4. The damage to the compressor indicated that both the compressor and the driver motor, acting as a flywheel, may have been subjected to extreme impulsive forces, with possible damage being caused to frames or shafts. However, subsequent inspections did show distortions to be negligible, and no cracks have been detected.
5. There was some evidence that liquid passes into this compressor in sufficient quantities under some conditions to cause mechanical distress.

The ROOT CAUSE is unknown.

hydrogen compressor

COMPRESSOR COMPONENT WHICH FAILED
A crosshead in a gas compressor is a reciprocating component that connects the piston rod to the connecting rod, acting as a sliding joint to convert rotational crankshaft motion into purely linear motion. It slides within guides to manage side loads and prevent lateral forces from bending the piston rod, reducing wear on cylinder liners and packing.
[Google Gemini answer, 11/04/2026]

No external fire occurred and the hydrogen product was out to stack.
The chlorine plant continued to run as required.