A member has reported a serious incident where a plate was being supported on a small length of tubular, which was mounted vertically. The tube was sealed at the bottom, but open to the atmosphere at the top end. The plate was about to be cut using an oxy-acetylene cutting torch mounted on a jig. The torch had been positioned at the side of the plate and was energised by the gases, in preparation for being ignited. This arrangement is shown below.
Gas was allowed, inadvertently, to flow freely into the open pipe. When the spark was struck to ignite the torch, entrained gas at the top of the open pipe alighted, causing a small explosion which resulted in a burn to the operator’s hand.
The member involved has noted that positioning a plate over a support which does not allow free dispersion of volatile gases ‘is not good practice’. Normal good practice is to support the work piece on supports that specifically avoid the build-up of a volatile mixture by, for example, the use of open trestles with sacrificial lugs.
It has reminded all those involved in metal fitting activities that they should assess the arrangements they have in place for cutting metal, to check that volatile gases are allowed to freely disperse. The member concerned has instructed its personnel to replace any arrangements that do not allow this before further cutting operations are conducted.
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