October 2001 Explosion due to aluminium welding
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.