AWS F4.1 PDF
These safe practices shall apply to the preparation for welding or cutting of metal containers and piping. For the purposes of this document, references to precautions for welding or cutting are also intended to apply to all metal working operations (i.e., brazing, grinding, soldering, thawing pipes, using heat guns, using spark-producing power tools, straightening, thermal spraying) involving heat. Cleaning of used containers is necessary in all cases before welding or cutting. The term container, as used herein, includes piping.
The safe practices presented here are not intended to replace either regulatory standards or more stringent practices of industries that have expert knowledge of handling hazardous substances. Even a water tank should be considered hazardous unless a qualified person has declared it safe to weld or cut. Consequently, safe practices presented here are not intended to apply to the following:1
(1) Containers and confined spaces that can be entered by workers (see ANSI Z117.1, Safety Requirements for Confined Spaces).
(2) Containers that have contained radioactive substances
(3) Compressed gas containers
(4) Containers that have held explosive substances (such as nitrocellulose, pyroxylin solution, etc.)
(5) Tanks, bunkers, or compartments on ships
(6) Gasometers or gas holders for natural and manufactured gases
(7) Outside, above-ground, petroleum storage tanks
(8) Containers holding flammables that are to be repaired while in service
1 See Annex A, Bibliography, for other standards and practices.
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