Before hot work begins on any surface with a preservative coating of unknown flammability, a competent person must test the coating to find out how flammable it is; a coating counts as highly flammable when its scrapings burn with extreme rapidity. Hardened coatings that are highly flammable must be protected against ignition, and where coatings prove highly flammable they are stripped off the zone that will be heated. Toxic preservative coatings: in enclosed spaces, all toxic coatings are removed for at least 4 inches around the point where heat is applied, or the workers are protected by airline respirators meeting subpart E; in the open air, workers are protected by a respirator that meets subpart E. In every case the coating is removed far enough from the heated area that the temperature of the metal still coated does not rise appreciably, and artificial cooling of the surrounding metal may be used to reduce the area that has to be cleaned.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.