OSHA interprets requirements for welding, cutting, and heating in confined spaces
OSHA issued this memorandum in 2019 to its regional administrators to provide clarification about how 29 CFR 1926.353(b)(1) applies when welding, cutting, and heating operations are performed within a confined space, in light of the promulgation of 29 CFR part 1926 subpart AA. As explained in its preamble, the requirements of subpart AA apply to all confined spaces hazards that are not specific to welding, cutting, and heating and addressed by the requirements of subpart J of 29 CFR Part 1926, Welding and Cutting (“subpart J”). Subpart J continues to apply to the hazards of welding, cutting, and heating in a confined space.
In applying section 1926.353(b)(1), regional administrators should be aware of a change in the definition of “confined space.” Prior to the promulgation of subpart AA, OSHA applied the definition of a confined space found in the former section 1926.21(b)(6) to section 1926.353(b)(1). In the confined spaces in construction rulemaking, OSHA replaced 29 CFR § 1926.21(b)(6) and its definition of a confined space with the definition of a confined space in subpart AA.
Now that OSHA has repealed the former definition of a “confined space” in construction and replaced it with the new three-part definition at 29 CFR 1926.1202, that definition should be used in determining whether a violation of the welding in confined spaces standard at 29 CFR 1926.353(b)(1) has occurred. As under the former definition, the hazard addressed is the accumulation of toxic or flammable contaminants. OSHA expects such accumulation would occur when welding in a confined space under the new definition because the welding, cutting, or heating task itself produces metal fumes, gases, and smoke, and there is an inherent risk of incapacitation should exposure levels to carbon dioxide, carbon monoxide, or smoke suddenly spike.
Under the terms of section 1926.353(b)(1), either general mechanical or local exhaust ventilation meeting the requirements of section 1926.353(a) “shall be provided whenever welding, cutting, or heating is performed in a confined space.” This language presumes that the act of welding, cutting, or heating in a confined space is hazardous and does not require OSHA to prove that exposure to a toxic substance exceeds a PEL for the application of section 1926.353(b)(1). As detailed in the de minimis criteria set forth in this memorandum, however, employers may avoid a citation by rebutting that presumption. Accordingly, the following citation policy shall apply:
Section 1926.353(b)(1) is triggered by the act of welding, heating, or cutting in a confined space, regardless of whether the atmospheric hazard within the space is likely to exceed any particular exposure level. If an employer has not implemented mechanical or local exhaust ventilation when welding, cutting, or heating is performed within a confined space, a serious violation of section 1926.353(b)(1) should be considered unless:
- Open ventilation is present, such as when a confined space has a substantial number of openings in its walls to outside the confined space (like a screen or open sections of rebar) or is entirely open on one side but still has limited or restricted means of access and egress. For example, to access or egress the space, a ladder, ramp, controlled descent device, etc. must be used; and
- The employer has conducted air sampling within the confined space where welding, cutting, or heating is being performed and determined that natural ventilation maintains the atmospheric hazard below the threshold limit values in Appendix A to 29 CFR 1926.55.
If the two bulleted factors above are established, the compliance officer should consider the employer’s failure to implement mechanical or local exhaust ventilation a de minimis violation unless air sampling demonstrates the existence of an atmospheric hazard.