Uncontrolled decompression during gangway move
- Safety Flash
- Published on 1 October 2004
- Generated on 3 December 2024
- IMCA SF 09/04
- 2 minute read
A member has reported that a man-way trunk and its adjacent entry lock on a hyperbaric chamber were depressurised to surface when a fitting on the man-way was struck by a gangway.
What happened?
The system was pressurised to 270fsw and vented to the surface in ten minutes through a ¼” penetrator. The system held four divers in saturation.
The were no injuries and, other than the fitting, no further damage was caused.
Initial findings of the investigation are that:
- the trunk fitting was unprotected from direct contact with the gangway.
- the crew had lost control of the gangway while raising it to allow a materials barge alongside.
- there had been a valve on the internal aspect of the trunk, but this had not been secured after the valve was hit.
- the loss of pressure in the adjacent entry lock was attributable to a misalignment of the chamber inner door, which was immediately and easily realigned following the incident.
Conclusion:
The potential for a less benign outcome for this incident was significant. Investigations are ongoing and the company will be issuing an internal memorandum on the issues surrounding this incident.
In the meantime, it has passed this alert to IMCA as a ‘heads up’ and a reminder that to expect and prepare for the unexpected is good advice. The company has asked all of its dive team members to scrutinise the arrangement of similar fittings on other diving spreads and to report any results which could predict the occurrence of a similar incident. Any proposed system modifications will then go through the company’s management-of-change process.
Particular points to be noted are:
- hyperbaric evacuation systems and other dive equipment on deck should be adequately protected from being struck by other objects;
- all internal doors within a hyperbaric system should be aligned properly.
IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of the entire offshore industry.
The effectiveness of the IMCA Safety Flash system depends on the industry sharing information and so avoiding repeat incidents. Incidents are classified according to IOGP's Life Saving Rules.
All information is anonymised or sanitised, as appropriate, and warnings for graphic content included where possible.
IMCA makes every effort to ensure both the accuracy and reliability of the information shared, but is not be liable for any guidance and/or recommendation and/or statement herein contained.
The information contained in this document does not fulfil or replace any individual's or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.
Share your safety incidents with IMCA online. Sign-up to receive Safety Flashes straight to your email.