The UK Diving Inspectorate has issued a safety alert about old aluminium cylinders used for scuba diving.
The safety alert concerns cylinders manufactured from aluminium alloys HE30/AA6082 and AA6351 and used primarily for gases for underwater breathing apparatus.
The aluminium diving cylinders referred to in this bulletin are typically over 23 years old. (They were manufactured from 1950 to 1995). It is highly recommended that these are no longer be used, dived or tested.
For sometime now a number of dive centres have recommended scrapping these cylinders because they are often uneconomic to service, not just due to the requirement for crack testing but also because many of the valves fitted (e.g. early Apeks / Typhoon etc) are obsolete. The cylinders were also mainly fitted with 3/4 BSP neck threads and whilst replacement 3/4 BSP valves are still available, this adds considerably to the cost of refurbishment.
Larger ali cylinders used as storage banks (23.5lt or 25lt) from 1950 - 1995 that cannot be eddy current tested because there is no adaptor for the neck also need to be scrapped. In addition 57, 60 or 70 cubic foot cylinders up to 1995 need to be scrapped.
During the period of this liaison, there have been serious incidents both in the UK and internationally where cylinders manufactured from aluminium alloys HE30/AA6082 and AA6351 have failed catastrophically.
As a result of this, the HSE in conjunction with manufacturers and industry experts have investigated these failures and have issued this safety alert.