"INTRODUCTION AND SCOPE The purpose of this data sheet is to outline safety precautions for preventing accidental fires and/or explosions while making hot-work repairs to the bottoms of tanks. For the purpose of this data sheet@ the term ""hot work"" is defined as any operation that will or can produce a spark or flame hot enough to cause the ignition of flammable liquids or vapors. Tanks that have contained flammable liquids must be considered unsafe for hot work@ regardless of age and type of construction@ until safety inspection proves otherwise. Special techniques are required in the performance of hot work on tank bottoms to prevent ignition of flammable liquids or vapors that may be entrapped under the tank. Although each tank bottom repair job must receive careful individual consideration@ the safety procedures described herein provide various methods for preparing tank bottoms for hot work. These procedures will be applicable to most situations."
API PSD 2207-1974 history
1974API PSD 2207-1974 Preparing Tank Bottoms for Hot Work (Second Edition)
1967API PSD 2207-1967 PREPARING TANK BOTTOMS FOR HOT WORK (First Edition)