A susceptibility to sustained load cracking (SLC) has been identified in cylinders manufactured from aluminium alloys of specific grades, manufactured between 1963 and 1995. Sustained load cracking is a metallurgical anomaly occurring in cylinders that have remained pressurised for sustained periods of time.

There have been two recent incidents of serious harm in the Asia-Pacific region caused by the catastrophic failure of self-contained underwater breathing apparatus (SCUBA) cylinders manufactured from aluminium alloy 6351. As a result of these incidents in August 2017 WorkSafe New Zealand issued a Safety Alert entitled "Cylinder design approvals withdrawn".

In its Safety Alert WorkSafe New Zealand announced that it had decided to withdraw approval for SCUBA and self-contained breathing apparatus (SCBA) cylinder designs which used aluminium alloy 6351. The withdrawal came into effect from 31 October 2017.

UK Health and Safety Executive (HSE) Safety Bulletin

On 8 March 2018 the UK HSE issued Safety Bulletin ED 1-2018 entitled "Cylinders manufactured from aluminium alloys HE30/AA6082 and AA6351 and used primarily for gases for underwater breathing apparatus".

The publication of this bulletin was prompted in part by the Asia-Pacific incidents, but also by an incident of serious harm caused by the failure of an HE30/AA6082 cylinder in England in 2017.

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