Near-miss: Potential use of petroleum-based grease in an oxygen-rich environment

A member has reported a near-miss incident involving the use of hydrocarbon-based grease in an oxygen-rich environment. A diving supervisor had asked an electrician to remove a seized COâ‚‚ scrubber motor from a deck decompression chamber (DDC) for repair. The electrician removed the motor to the workshop, where it was dismantled, cleaned and the bearing lubricated with petroleum-based grease.

The use of petroleum-based grease on a motor to be used in an oxygen-rich environment (as on a COâ‚‚ scrubber in a diving bell) could cause self-ignition and fire, with resulting injuries or fatalities.

It was realised that petroleum grease had been used before the motor was refitted. The motor was discarded and a new motor used instead.

The following points were noted:

• The diving supervisor had not advised the electrician that petroleum-based grease should not be used;
• The electrician was unaware that petroleum-based grease was not to be used;
• The fact that grease was applied to the bearing was detected and immediately the scrubber motor was discarded.

The company involved has made the following recommendations:

• Procedures for repair or maintenance of any item should specify special requirements (if any) for that item;
• Diving/life support equipment should only be serviced by appropriately experienced and qualified personnel;
• Diving/life support equipment should always be checked by appropriately qualified personnel following repair, to ensure all appropriate service and maintenance safety precautions are taken.