Work was being undertaken servicing an engine. Immediately prior to the accident the first cylinder head had been removed using the equipment and procedures normally used for this task. The hydraulic power tool for tensioning the main retaining bolts (regulated at 500 bar) was applied and pressured up to 490 bar. The injured person’s left hand was on the body of the jack. As he slackened the main nut on the tensioned bolt a small release of HP oil was injected into his left hand.
The cause of the release was the failure of an HP seal on the hydraulic jack that allowed a high velocity discharge of a small quantity of hydraulic oil to be released through a small aperture. The failure was attributed to a missing backup ‘o’-ring seal. Even though the injured person was wearing PPE, the jet of oil penetrated his left hand.
The reason for the missing backup ‘o’-ring could not be established. It was either omitted by the manufacturer or during maintenance. The risk assessment that was carried out did not identify that high pressure could be contained within the jack.
The company involved has identified the following:
- the need for a specific procedure regarding the changing of seal/’o’-ring assemblies;
- investigation and availability of gloves that provide additional protection against equipment that may involve high pressure hazards;
- hydraulic jacks should be included on planned maintenance system;
- additional PPE (full face visors) to be worn while performing this task in future.
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