65. Welding and cutting on containers that held flammable substances

Where any operation involving welding or cutting is carried out in a shipyard or on board a ship in a harbour on any container that has held any explosive or flammable substance or in which flammable gases may have been generated, it shall be the duty of —

the employer of any person who carries out the operation; or

the principal under whose direction any person carries out the operation,to ensure that no such operation is carried out on the container unless —

the container has been thoroughly cleaned by steam or other equally effective means and is completely free from combustible gases or vapours; or

the atmosphere in the container has been rendered non-flammable or non-explosive.