Diving helmet locking collars
One of our members has brought to our attention that certain Kirby Morgan diving helmets, type KMB 601, neck dam locking collars have been subjected to pitting during oxy-arc cutting due to electrolysis. These particular locking collars were all made of cadmium-plated aluminium alloy.
On investigating this matter with the supplier and manufacturer, the contractor has been advised that only a small quantity of cadmium-plated aluminium alloy locking collars were manufactured. The supplier has not been able to quantify the number of such collars sold, nor identify to whom they were sold.
Because of the electrolysis action, the manufacturer has now reverted to traditional brass or stainless steel locking collars.
It is not thought that the aluminium alloy locking collars will represent a safety hazard if regularly inspected before use. However, as deterioration has been observed, the contractor involved has decided that it would be prudent to replace all their aluminium alloy locking collars.
Safety Event
Published: 1 January 2000
Download: 
IMCA SF 01/00
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