Hot Work Permit Standards

Hot Work Permit requirements are addressed in NFPA 51B from the National Fire Protection Association.

The NFPA 51B standards include the concept of designated areas and permit-required areas (Sec. 5.1.2). Designated areas, where hot work permits are not required, include “A designated area shall be a specific area designed or approved for hot work, such as a maintenance shop or a detached outside location that is of noncombustible or fire-resistive construction, essentially free of combustible and flammable contents, and suitably segregated from adjacent areas..” (Sec. 5.1.2.1). In many/most cases, hot work in shops and in outdoor locations may not require hot work permits if the area meets the aforementioned criteria.

NFPA 51B Section 5.3.3 states, “Based on local conditions, the PAI [Permit Authorizing Individual] shall determine the length of the period for which the hot work permit is valid.” NFPA 51B Section 5.3.4 states, “The area shall be inspected by the PAI at least once per day while the hot work permit is in effect to ensure that it is a fire-safe area.” NFPA 51B Section 6.1 allows individual hot work operators to be permitted to serve as PAI, which is how KU’s Hot Work Permit program operates. Therefore, our expectation is that a Hot Work Permit will be valid for the duration of the “temporary operations involving open flames or producing heat and/or sparks… [including but not limited to] brazing, cutting, grinding, soldering, thawing, and welding.” The maximum duration of a hot work permit will be two weeks.

1. A contractor cuts metal framing in a permit-required area, assuming it’s not feasible to remove by a “cold” method and not feasible to remove from the premises and then cut it. The hot work lasts 30 minutes.
2. Same as #1, except the hot work spans several days.
3. Same as #2 above, except the contractor is cutting metal and grinding the edges and soldering pipes in the same general area and in the same timeframe.

1. Subcontractor A welds beam plates to increase floor load capacity for heavy equipment in a permit-required area, assuming it’s not feasible to join by a “cold” method and not feasible to weld in a designated area and then bring it in. Subcontractor B is thawing a frozen pipe in the same building.
2. Same as #1 above, except Subcontractor B is working in the same room as Subcontractor A.
3. Same as #2 above, except the various hot work operations are separated by intervals longer than a day or more.