November 28, 2012 | Mark Paradies


Here is a safety alert from OPG that I am passing along …

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A number of Air Decompression chambers have been identified during verification audits that contain serious safety hazards.

1. A decompression chamber was recently found carrying a genuine Identification plate complying with ASME PVHO requirements fitted after construction. This decompression chamber had a subsequent engineering modification with the addition of a medical equipment lock (photo 1), this modification was not carried out by the original manufacturer, and contrary to ASME PVHO requirements the Identification/ Certification plate was not amended.

• The engineering quality of the modification was grossly incompatible with the standards required by ASME PVHO (photo 1& 2).

• No pressure test had ever been conducted on the external door of the medical lock. Should the Medical lock have been used as designed, the lack of engineering quality increased the probability of catastrophic failure and explosive decompression, resulting in the death of the chamber occupants.

• This Chamber had been owned by various Diving Contractors and equipment suppliers, none of which identified the modification.

2. A number of Decompression chambers manufactured under ASME PVHO standard have been identified that contain corrosion grossly in excess of the maximum tolerance required by ASME PVHO standard and with the subsequent risk of pressure vessel rupture and death of the occupants.

• The location of the corrosion is between the 5 and 8 o’clock position on the outer lock to inner lock shell. (Sketch 1 & 2, & photo 3).

• This corrosion is the product of poor maintenance during the working life of the chamber

• In many cases observed, erroneous actions were taken to repair this corrosion. These include, lacquering with successive layers of paint, filling the corrosion area with packer material or weld bead material and grinding flush prior to repainting.

What Went Wrong?:

• Failure to maintain equipment to the manufacturer’s standards

• Failure to maintain records of design, construction, modification and testing

• Failure of inspection auditors to identify non compliance and corrosion.

Corrective Actions and Recommendations:

• Verify Decompression chambers are designed, constructed, tested and maintained to a recognised standard.

• Check all documentation is available for the chamber.

• Verify with the issuing authorities that the documentation is accurate.

• Inspect chambers for compliance and corrosion hotspots.

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