Safety update

October 2001 Explosion due to aluminium welding

This safety update is issued to raise awareness of the potential serious risk to safety from aluminium welding. It provides information on how best to reduce the risks involved.


An explosion occurred on an aluminium dinghy whilst a worker was attempting to weld a lug plate onto the floor pan (both parts aluminium). Due to this explosion the worker sustained serious injuries. This was investigated by a Safety Inspector, Occupational Safety & Health Service, Department of Labour and the following have been revealed:

  • The most likely cause of ignition was from the welding torch.
  • It is believed that the formation of the combustible mixture was due to the generation of Hydrogen by:
    • a reaction between aluminium corrosion and moisture.
    • decomposition of water due to very high thermal energy of the welding arc.
    • release of hydrogen trapped in the gas pores of welds attaching the floor to the hull.

Precautions and procedures

Those involved in aluminium welding on board ships/boats/barges/tanks or similar marine vessels must therefore take adequate precautions to prevent the accumulation of a combustible mixture, by ensuring there is good ventilation when carrying out welding work on aluminium.

Original source content - Boat Notice 082001, October: Explosion due to aluminium welding.

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