(d)the vessel does not undergo repair by hot work to any of its tanks, part of fittings which are likely to contain petroleum vapour or petroleum unless each such tank, part of fittings, as the case may be, has been examined by an officer appointed under clause (c) with the aid of an approved petroleum vapour-test instrument and has been certified by him in writing that the tank, part or fittings is free from petroleum vapour or petroleum;
