Near-miss: Release of trapped pressure after ROV dive

A member has reported an incident in which there was an unplanned release of trapped pressure from part of the tooling frame under an ROV. The incident occurred when it was noted that the frame was not deploying correctly and was slightly twisted. Upon investigation the coil mounting frame had been fitted upside down. The crew began to remove the cross member using an Allen key to separate the frame into two sections for removal and to ease the handling during the turning over portion of the task.

Upon the first quarter turn of the port side Allen bolt, a hissing noise was heard. The supervisor immediately evacuated the area and had it barriered off.

The system was left to bleed down naturally. The risks of the job were re-assessed and additional personal protective equipment (PPE) was identified for further work in removing the frame.

Causal factors:

• The potential for trapped pressure had not been identified;
• The frame had been incorrectly fitted.

The following actions were taken:

• An engineering solution was identified to prevent possibility of trapped pressure – holes drilled in cross-member;
• Safety flash issued;
• Other similar systems checked and modified as required;
• Clear markings applied to ensure correct frame orientation.

Members may wish to refer to the following incident:

• First aid injury: Thermos cup exploded after being in hyperbaric environment