Hot Work Permit Requirements: Who Requires One, and What Has to Be On It

A lot of hot work programs are built on a claim that is not true, that OSHA requires a written permit. In general industry it does not. What it requires is that a designated person inspect the area and specify the precautions before the torch comes out. But if you run a covered process, a permit is federally mandatory, and NFPA 51B, an adopted fire code, or your property carrier will typically require one regardless. This guide covers what a permit has to accomplish, block by block, who signs it, how long it stays good for, and who is accountable when a contractor is holding the torch.

Last updated: July 26, 2026

The short version

OSHA does not require a written hot work permit in general industry. 29 CFR 1910.252(a)(2)(iv) requires an area inspection by the designated authorizing individual, who then specifies the precautions, and says a written permit is preferred.
If you run a process covered by OSHA process safety management, a permit is federally mandatory under 29 CFR 1910.119(k)(1). That is most refineries, petrochemical plants, and chemical plants.
NFPA 51B and the International Fire Code where it is adopted require a written permit, and many property insurers, FM Global among them, require or recommend a permit system as an underwriting and loss-prevention condition. If any one of those reaches your facility, "OSHA does not require it" is a weak reason not to have one.
A permit certifies a verified condition, not a task. Conditions decay, which is why FM Global limits authorization to a single shift and NFPA 51B has the authorizer re-inspect the area daily while a permit is open.
In the fatal cases the Chemical Safety Board has summarized, the failure is rarely a blank line on a form. It is no program at all, a gas test taken hours earlier, or a dispute over who authorized the work.

What OSHA actually requires

The controlling paragraph in general industry is 29 CFR 1910.252(a)(2)(iv), headed "Authorization." It reads: "Before cutting or welding is permitted, the area shall be inspected by the individual responsible for authorizing cutting and welding operations. He shall designate precautions to be followed in granting authorization to proceed preferably in the form of a written permit."

Read it one clause at a time. Three things are mandatory and one is not.

The area shall be inspected before the work is permitted. Mandatory.
The inspection is done by the individual responsible for authorizing the work. Mandatory, and it presupposes that management designated someone, which 1910.252(a)(2)(xiii)(B) separately requires.
That person shall designate the precautions to be followed. Mandatory.
Those precautions are issued as a written permit. Preferably. Not mandatory.

The Chemical Safety Board says the same thing in plain language in its 2010 hot work safety bulletin: this regulation prefers but does not require a written permit for hot work. What OSHA mandates in general industry is authorization. The written permit is how OSHA prefers you document it.

The exception that covers our readers. If your facility has a process covered by OSHA process safety management, a permit is federally required. 29 CFR 1910.119(k)(1): the employer shall issue a hot work permit for hot work operations conducted on or near a covered process. 1910.119(k)(2) sets the minimum contents. The permit shall document that the fire prevention and protection requirements of 1910.252(a) were implemented before the work started, indicate the dates authorized, and identify the object the work is performed on, and it is kept on file until the work is complete. PSM-covered construction work is routed to the same requirement by 29 CFR 1926.64.

Two adjacent standards are worth knowing so you do not assume coverage you do not have. In construction, 29 CFR 1926.352 contains no permit requirement at all, and no distance figure either. In permit-required confined spaces, 29 CFR 1910.146(b) defines what a hot work permit is and 1910.146(f)(15) requires that one, if issued, be identified on the entry permit, but 1910.146 does not itself compel you to issue one.

For the paragraph-by-paragraph structure of the welding standard, including the 35-foot rule and the conditions that trigger a fire watch, see OSHA 1910.252. State plan states may impose requirements beyond the federal floor, so confirm what your jurisdiction has adopted.

Who does require a permit, and how hard

The useful question is not whether a permit is required, it is which authority requires it of you and what happens if you do not have one. Four kinds of force are in play and they are not interchangeable. A federal regulation is enforceable by an OSHA inspector. A model code is enforceable only where a state or local jurisdiction has adopted it. A consensus standard is voluntary until something adopts it or a contract invokes it. An insurer requirement is contractual and can be stricter than all three.

Authority	Does it require a written permit	Force
OSHA general industry, 29 CFR 1910.252(a)(2)(iv)	No written permit. It requires an area inspection by the individual responsible for authorizing the work, who then designates the precautions. The written permit is stated as a preference.	Federal law
OSHA process safety management, 29 CFR 1910.119(k)(1)	Yes. A hot work permit is required for hot work on or near a covered process, and 1910.119(k)(2) sets out what it has to document.	Federal law
OSHA construction, 29 CFR 1926.352	No permit requirement in the section at all. PSM-covered construction work reaches the 1910.119(k) permit through 1926.64.	Federal law
NFPA 51B	Yes. A written permit issued by a permit authorizing individual is the center of the standard.	Consensus standard
International Fire Code, Chapter 35	Yes, under a hot work program. IFC 3503.3 requires permits to be available to the fire code official while the work is being done and for 48 hours after it is complete.	Law where adopted
Property insurers, such as FM Global Data Sheet 10-3	Yes, plus permit expiration limits, contractor supervision, retained records, and at least annual audits of the program.	Underwriting condition

Read the rows together and the practical answer falls out. Very few industrial facilities are reached by federal OSHA alone. Most are in a jurisdiction that has adopted a fire code, carry property insurance with a hot work condition, or have a customer specification that invokes NFPA 51B. Any one of those makes a written permit obligatory for you even though 1910.252 does not.

NFPA 51B is the document most of the modern permit machinery comes from, including the permit authorizing individual role and the longer post-work fire watch. How it reaches an employer, and the fact that the edition OSHA incorporates by reference is from 1962, is covered on the NFPA 51B page.

What goes on the permit, block by block

The block list below is drawn from three real published forms: the FM Global hot work permit that ships as an appendix to Data Sheet 10-3, the University of Michigan internal hot work permit, and the example checklist and permit in OSHA fact sheet FS-4188. They differ in wording and length but they cover the same ground, because the permit is not paperwork. It is the artifact that proves a specific person verified a specific condition at a specific time.

Block	What it has to capture
Identification	Date and job number. Location down to the building, floor, room, or object. The scope of work. Whether the work is by an employee or a contractor. The name of the person doing the work, the name of the fire watch during it, and the name of whoever watches or monitors afterward. Emergency contact numbers.
Type of hot work	Grinding, welding, torch or air-arc or plasma cutting, brazing, soldering, pipe thawing, torch-applied roofing. The precautions that follow depend on which box is checked, so this is not a filing detail.
Fire protection status	Fire pump running and switched to automatic. Sprinkler control valves open. Extinguishers, hose, and the hot work equipment itself in service and operable. Whether any detection or alarm near the work has been temporarily disabled, which creates an obligation to turn it back on at closeout.
Precautions within 35 feet	Combustible construction shielded with listed or approved welding pads, blankets, or curtains. Movable combustibles relocated. Flammable liquid, dust, lint, and oily deposits removed. Floors swept, and combustible floors wet down or covered. Wall and floor openings covered. Ducts and conveyors that could carry sparks covered or shut down. Sources of flammable gas, ignitable liquid, or combustible dust isolated.
Walls, ceilings, and roofs	Whether the assembly is noncombustible and free of combustible coverings or insulation. Whether combustibles on the far side have been moved. Whether a second watch is needed on the opposite side, which it is wherever an opening or a thermally conductive member such as metal piping or a steel structural member passes through the assembly.
Closed equipment, ductwork, and piping	Equipment isolated from service. Ignitable liquid drained, with low points identified and verified clear. Flammable gas and vapor purged. Pressurized systems vented. Combustible dust, lint, and nonremovable combustible linings identified. The actual LEL readings written on the face of the permit, before the work and again during it.
Fire watch and monitoring	Who watches during the work, who watches after it, how long each period runs, what extinguishing equipment they have, that they are trained to use it, and whether adjoining areas, the level above, or the level below need a watch of their own.
Authorization and closeout	The authorizer signs that the area was examined and the precautions taken. The permit carries an expiration date and time. Start time, finish time, the end of the post-work watch, the end of monitoring, and a final check are each signed with a name and a time. This is the block most often left blank.

Two things about that list deserve more than a row. The first is that the LEL readings go on the face of the permit with the times they were taken, not in a separate log. The second is that the closeout block is where programs quietly fail. A permit with an authorization signature and no finish time, no watch-end time, and no final check tells you the form was filled out and the process was not.

The insurer form is worth understanding structurally, because it explains why the permit is a multi-part document rather than a single sheet. One part stays with the authorizer. A second part, printed as a warning placard, is posted at the work site for the duration and comes back signed at closeout. The posted copy is doing three jobs at once: warning anyone who walks up that hot work is in progress, reminding the crew what precautions the permit was issued on, and recording the during-work and post-work sign-offs as they happen.

On the fire watch block. The durations belong to different authorities and they do not agree. OSHA general industry sets a floor of at least 30 minutes after the work stops, at 29 CFR 1910.252(a)(2)(iii), while NFPA 51B sets a 60-minute minimum, with any additional monitoring period determined by the permit authorizing individual and running up to three hours. Never write a number on a permit or a program document without naming which authority it came from. Durations by authority, who is allowed to serve, and the certification question are covered in the fire watch requirements guide.

The permit authorizing individual

NFPA 51B defines the permit authorizing individual, usually shortened to PAI, as the person management designates to authorize hot work. Insurers call the same role the permit authorizer. The title is newer than the duty. OSHA created the duty in 1910.252(a)(2)(xiii)(B), which requires management to designate an individual responsible for authorizing cutting and welding operations in areas not specifically designed for those processes, and OSHA now uses the PAI term itself in its own fact sheet guidance.

The welding standard actually builds a three-tier accountability structure, and it is worth naming all three because programs tend to collapse them into one person and then wonder why nobody caught the hazard.

Management, 1910.252(a)(2)(xiii). Establishes designated cutting and welding areas based on the fire potential of the facility, names the authorizing individual, ensures cutters, welders and their supervisors are suitably trained, and advises contractors about flammable materials and hazardous conditions.
Supervisor, 1910.252(a)(2)(xiv). Responsible for safe handling of the equipment, for determining what combustibles and hazardous areas are present, for protecting combustibles from ignition, for securing authorization, for verifying that fire protection equipment is properly located, and for making sure fire watches are actually available at the site.
Authorizing individual, 1910.252(a)(2)(iv). Inspects the area and designates the precautions before the work begins.

What NFPA 51B adds is a duty of protection rather than a duty of paperwork. Under the standard the authorizing individual is responsible, along with management, for the safe operation of the hot work, and is expected to work through a hierarchy: consider an alternative to hot work, move the work somewhere free of combustibles, and only then move or shield the combustibles and schedule the work so nothing else exposes them. OSHA writes the same hierarchy as a hard stop at 1910.252(a)(1): move the movable hazards, guard what cannot be moved, and if neither can be done, the work shall not be performed.

Published university programs fill in the practical duty list: know the process and the applicable regulations, determine the type of hot work and who is doing it, conduct the pre-work fire-safe check, assess the area for site-specific flammable materials and hazardous processes, issue the permit before work starts, decide whether a fire watch is required, and where one is not, personally perform the final check afterward.

What qualifies someone to be the authorizer. Federally, nothing. There is no OSHA credential, exam, or hour requirement for the role. OSHA requires only that management designate someone and that cutters, welders and their supervisors be suitably trained, with no prescribed curriculum and no required record. Property insurers are stricter and expect initial and annual refresher training for authorizers, and a small number of jurisdictions require documented, approved hot work training for anyone issuing permits. Find out which of those reaches you before deciding your program is adequate because OSHA has not objected.

How long a permit lasts, and what happens if the job changes

A permit certifies a verified condition, not a task. That single idea explains every rule in this section. Conditions decay. Housekeeping resets, combustibles get restaged, adjacent work starts, a sprinkler control valve gets closed for something unrelated, the shift changes. The shorter the validity window, the closer the permit stays to the condition it actually certified.

NFPA 51B leaves the window to the authorizer. The standard has the permit authorizing individual set the validity period based on local conditions, and requires the area to be inspected at least once a day while the permit is in effect, and caps any single permit at 24 continuous hours.
FM Global limits authorization to a single shift. An extension at shift change is acceptable only if an authorizer reviews the permit, re-verifies that the required precautions are still in place, sets a new expiration date, and re-signs it.
Institutional programs mostly land on one day. Published university permits carry "good for one day only" on the face of the form. Others set the duration case by case depending on the project and the type of work. Both are defensible. An open-ended permit is not.
Retention is a separate question from validity. Under process safety management the permit indicates the dates authorized and is kept on file until the work is complete. Where the International Fire Code is adopted, permits and prework check reports have to remain available to the fire code official for at least 48 hours after the work is finished. Insurers expect completed permits to be retained for program auditing.

Scope lock is the rule most often broken. The permit authorizes a defined type of hot work at a defined location. If the work moves, if a grinder comes out on a permit written for welding, or if the crew starts on the next joint down the line, the hot work area has changed and so have the required precautions. The correct response is to stop and reauthorize, not to carry the original permit forward. Insurer loss files include a case where a facility used a general work permit that called for a fire watch instead of a hot work permit, and the outcome was the same as using none, because the combustibles were never removed or protected.

Designated areas: exempt from the permit, not the program

Most facilities have somewhere hot work happens every day. NFPA 51B calls it a designated area and describes it as a space designed or approved for hot work, a maintenance shop or a detached outside location, of noncombustible or fire-resistive construction, essentially free of combustible and flammable contents, and suitably segregated from adjacent areas. Work inside it does not need a per-job permit. OSHA supports the concept from the other direction: at 1910.252(a)(2)(xiii)(A), management establishes areas for cutting and welding based on the fire potential of the facility, and establishes procedures for cutting and welding in other areas.

The exemption is from the permit and never from the program. The International Fire Code puts it directly: hot work is only conducted in areas designed or authorized for that purpose by the personnel responsible for a hot work program. If there is no program, there is no designated area, only a room where people weld.

What still applies inside a designated area:

Scheduled inspections with retained records. Property insurers expect at least monthly inspection of designated areas, and weekly inspection where only low-energy hot work is done.
The area kept free of combustible, ignitable, and flammable materials, with ignition sources contained inside it. Where full enclosure is not practical, that means listed or approved welding curtains or blankets at unprotected openings, or a marked clear separation distance at the open sides.
Construction that holds up. Noncombustible walls and ceiling assemblies, impact-resistant facing on surfaces that take mechanical damage, and sealed joints between floors, walls, and ceilings so sparks cannot escape the room through a gap nobody looked at.
Trained people. Employees who work in a designated area, and those inspecting it, have to be trained to keep the conditions that qualified it.
A post-work period anyway. FM Global still calls for at least 30 minutes of fire monitoring after low-energy hot work in a designated area.

The drift problem. Designated areas fail slowly. Pallets get staged inside for a week. A welding curtain is left open. A new conduit penetration is cut through a wall that was sealed. Nothing announces the change, and everyone keeps working permit-free in a space that stopped qualifying. The monthly inspection requirement exists to catch exactly that. Define the boundary on a building plan, mark it on the floor, and train authorizers and hot work personnel to recognize where it is and how a change gets communicated.

One assumption to retire: outdoors is not a designated area by default. An outdoor location still has to be approved and maintained as a fire-safe designated area, because yard storage and combustible construction are usually present, and because wind is the reason elevated and drafty work carries a larger hot work area than the same job indoors.

Contractors and multi-employer sites

Most of the hot work in a plant during a turnaround is done by someone who does not work there. That is where authorization gets ambiguous, and OSHA has been clear for a long time that ambiguity does not reduce anyone's exposure.

The duty to warn is a federal requirement. 1910.252(a)(2)(xiii)(D) requires management to advise all contractors about flammable materials or hazardous conditions of which they may not be aware. That is your material, your process, and your history in the building. The contractor cannot know it.
Under process safety management it is spelled out. 1910.119(h) requires the host to evaluate the contractor safety performance, inform contract employers of known fire, explosion, and toxic release hazards related to their work and to the process, explain the emergency action plan, control entry into covered process areas, and periodically evaluate the contractor. The contract employer has to train its people, document that training, and advise the host of hazards its own work presents or uncovers.
OSHA can cite more than one employer. Under the multi-employer citation policy, CPL 02-00-124, each employer is classified as creating, exposing, correcting, or controlling, and then judged on whether its actions met that role. A facility with general supervisory authority over the site is normally the controlling employer and owes reasonable care, which is a lower standard than what it owes its own employees but is not nothing. Inspection frequency scales with the size and pace of the work and with what the facility knows about that contractor. An unknown contractor or one with a poor record warrants more frequent inspection, not less.
The carrier has a number for it. FM Global loss history, as quoted by the Chemical Safety Board, shows the risk of fire can increase over 100 percent when outside contractors are involved in hot work without facility supervision.

The arrangement that works. Contractors use the facility permit, and the facility authorizer signs it. That is the sample policy language insurers publish, and it resolves the failure mode directly. In one Chemical Safety Board case a worker was killed and three were injured, and afterward the host said the contractors were not authorized to weld in that area and no permit had been issued, while the contractor said the work was authorized and gas monitoring had been done. Where the authorization is verbal, or where a contractor issues its own permit into someone else's building, there is no artifact that settles the question.

Equipping a hot work program across multiple sites?

Tell us what the work looks like and how many locations you are covering. We quote the equipment side of a hot work program: extinguishers staged at the work area, portable gas detection, non-sparking tools, and cylinder handling and storage. We do not write your permit program, train your authorizers, or make code determinations.

or call 714-248-6555 · email partners@usmadesupply.com

What actually goes wrong

The case for a permit is not that a regulator wants one. It is that the same small set of failures keeps killing people, and each one is something a permit is designed to catch. The Chemical Safety Board has identified over 60 fatalities since 1990 from explosions and fires during hot work on tanks, and its 2010 safety bulletin summarizes eleven of those incidents. The pattern below is drawn from that bulletin and from CSB's later investigation of the 2017 Packaging Corporation of America explosion in DeRidder, Louisiana.

Partridge-Raleigh Oilfield, Raleigh, Mississippi, June 5, 2006. Three killed, one seriously injured. Neither the contract company nor Partridge-Raleigh required written hot work permits. Interconnected tanks were not emptied or isolated, and workers had checked a tank for flammable vapor by using a lit torch.
Bethune Point Wastewater Plant, Daytona Beach, Florida, January 11, 2006. Two killed, one critically injured. No formal permitting system existed for hot work or for non-routine maintenance, there had been no methanol hazard training in ten years, and no combustible gas monitoring was performed.
Packaging Corporation of America, Tomahawk, Wisconsin, July 29, 2008. Three killed, one injured. Anaerobic bacteria likely produced hydrogen inside an 80-foot recycled-water and fiber-waste tank. No hazard analysis had been performed, the fiber waste tanks were not recognized as potentially hazardous, and combustible gas monitoring was not required for the work.
Philip Services Corporation, Kapolei, Hawaii, October 7, 2008. One killed, three injured. The host asserted the contractors were not authorized to weld in the dike area and that no permit had been issued. The contractor asserted the work was authorized and monitoring had been done. Nothing in writing existed to resolve it.
ConAgra Foods, Boardman, Oregon, February 16, 2009. One killed. No hot work permit was issued, and gas testing was done only from the tank entrance rather than at the crack being repaired or in the adjacent skirt space where gas from bacterial decomposition had collected.
TEPPCO Partners, McRae Terminal, Garner, Arkansas, May 12, 2009. Three killed. Both a confined space permit and a hot work permit were issued. The permit documented gas testing at 7:00 a.m., the start of the shift. No documentation exists of testing after the crew returned from lunch or when torch cutting of the floating roof began. The explosion happened at about 2:30 p.m. CSB's finding: work atmospheres can change rapidly, and gas monitoring needs to be conducted immediately before and during hot work.
Motiva Enterprises Refinery, Delaware City, Delaware, July 17, 2001. One killed, eight injured. Written permits existed but the program was inadequate. Hot work was allowed near tanks containing flammables, including tanks with known corrosion holes, and continuous atmospheric monitoring was not required. Five hours passed between the last gas test and the explosion, during which the ambient temperature rose 14 degrees.
Packaging Corporation of America, DeRidder, Louisiana, February 8, 2017. Three contract workers killed, seven injured, during welding and grinding on pipes above and connecting to a 100,000-gallon foul condensate tank. The explosion launched the tank over a six-story structure, landing roughly 375 feet away. CSB found more flammable turpentine on top of the water than expected and, in the months beforehand, confusion over who was responsible for the tank's operations, which allowed the turpentine to accumulate. CSB concluded the explosion could have been prevented had a process hazard analysis been conducted.

CSB's seven key lessons from the bulletin are the shortest useful statement of what a program has to do: use alternatives to hot work where possible; analyze the hazards before the work starts; monitor the atmosphere with a properly calibrated combustible gas detector before and during the work, even where a flammable atmosphere is not expected; drain, purge and test surrounding tanks and adjacent spaces, not just the one being worked on; use written permits issued by qualified personnel familiar with the site hazards; train personnel in a language they understand; and supervise contractors and inform them of site-specific hazards.

The property-loss cases are different in character and worth reading alongside them, because several happened with a completed, authorized permit in hand. In one insurer loss file a corrugated box plant had a permit with the precautions checked off and a supervisor signature, and still lost the building when grinding sparks reached paper dust on the joists and ceiling underside that the program had never recognized. In another, a sawmill provided the full hour of fire watch and three hours of monitoring that the carrier calls for, and the fire started roughly six and a half hours after the last hot work, in concealed spaces inside an exterior wall, and burned for fifteen hours. Combustibles there had been wet down instead of removed or covered.

Sorted, the failures come out as a short list. Every item below is traceable to a documented incident:

No program and no permit at all, which dominates the fatal cases
The wrong permit used for the hazard actually present
A permit issued by someone without site-specific knowledge of the hazard
Precautions checked off on paper but never physically verified
Atmosphere tested once at shift start instead of immediately before and during the work
Combustibles wet down instead of removed or isolated
Concealed spaces, pits, cable trays, and thermally conductive members never inspected
Combustible linings inside otherwise noncombustible equipment not recognized
A fire protection impairment never coordinated with the hot work permit
Permit scope quietly expanded after authorization

The framing worth adopting. Property carriers treat any hot work fire or explosion, regardless of size, as a failure of the hot work management program rather than as bad luck, and they say plainly that no length of post-work watch and monitoring substitutes for preparing and maintaining the work area. That is the correct way to read the incidents above. The permit is not the safety measure. It is the record that the safety measures were taken by a named person at a known time.

Frequently Asked Questions

Does OSHA require a written hot work permit?

Not in general industry. 29 CFR 1910.252(a)(2)(iv) requires that the area be inspected before the work by the individual responsible for authorizing cutting and welding, and that this person designate the precautions to be followed, "preferably in the form of a written permit." Preferably is not shall. The Chemical Safety Board describes it the same way in its 2010 hot work bulletin: the regulation prefers but does not require a written permit. A permit is federally mandatory in one situation, under the process safety management standard at 29 CFR 1910.119(k)(1), and it is required by NFPA 51B, by the International Fire Code where that code is adopted, and by many property insurers as an underwriting or loss-prevention condition.

Which facilities are federally required to issue a hot work permit?

Facilities with a process covered by OSHA process safety management. 29 CFR 1910.119(k)(1) requires the employer to issue a hot work permit for hot work conducted on or near a covered process. That reaches refineries, petrochemical plants, and chemical plants holding threshold quantities of highly hazardous chemicals. PSM-covered construction work gets there too, because 29 CFR 1926.64 points construction back to 1910.119.

What has to be on a hot work permit?

Federally, under 1910.119(k)(2), only three things: documentation that the fire prevention and protection requirements of 1910.252(a) were implemented before the work started, the dates authorized for the hot work, and identification of the object the work is performed on. The permit is kept on file until the work is complete. Real permit forms published by insurers and by large institutional programs go much further, covering identification, the type of hot work, fire protection status, precautions within 35 feet, work on building assemblies, work on closed equipment and piping including recorded LEL readings, the fire watch and monitoring assignments, and a signed authorization and closeout.

Who signs a hot work permit, and can the welder authorize their own work?

Management designates the individual responsible for authorizing hot work outside designated areas, under 29 CFR 1910.252(a)(2)(xiii)(B). NFPA 51B calls that person the permit authorizing individual, a term OSHA also uses in its shipyard-employment guidance under Part 1915 rather than in the general-industry rule. The authorizer signs that the area was examined and the precautions were taken. The fire watch signs at the end of the watch, the monitor signs at the end of monitoring, and a final check is signed. NFPA 51B (2019 edition) does allow a hot work operator to serve as the permit authorizing individual, and some published university programs are run that way, but that is a deliberate structural choice rather than a default. It is separate from the fire watch question: the person performing hot work cannot be the fire watch during that work.

How long is a hot work permit valid?

NFPA 51B (2019 edition) leaves the validity period to the permit authorizing individual based on local conditions, subject to an outside limit of 24 continuous hours, and requires the area to be inspected at least once a day while the permit is in effect. FM Global limits authorization to a single shift, and allows an extension at shift change only if an authorizer re-verifies the precautions, sets a new expiration date, and re-signs. Published institutional permits commonly read "good for one day only." Under process safety management the permit indicates the dates authorized and is kept on file until the work is complete, and where the International Fire Code is adopted, permits have to remain available to the fire code official for 48 hours after the work.

Do we need a permit to weld in our own weld shop?

Not a per-job permit, if the shop genuinely qualifies as a designated hot work area. NFPA 51B (2019 edition) describes a designated area as one designed or approved for hot work, of noncombustible or fire-resistive construction, essentially free of combustible and flammable contents, and suitably segregated from adjacent areas. What you do not get is an exemption from the program. The area still has to be inspected on a schedule with records kept, stay free of combustibles, and be staffed by trained people, and the IFC states plainly that hot work is only conducted in areas designed or authorized for that purpose by the people responsible for the hot work program. Outdoor locations are not designated areas by default.

Who is responsible when a contractor does hot work in our building?

Both parties, and OSHA can cite both. Under the multi-employer citation policy, CPL 02-00-124, a facility running the site is typically the controlling employer and owes reasonable care, with inspection frequency scaled to the scale and pace of the work and to what it knows about that contractor. The contractor is usually the creating and exposing employer. 29 CFR 1910.252(a)(2)(xiii)(D) requires management to advise all contractors about flammable materials and hazardous conditions they may not be aware of, and under process safety management, 1910.119(h) makes that explicit and adds a duty on the contractor to report hazards its own work creates or uncovers. In practice the workable arrangement is that contractors use the facility permit and the facility authorizer signs it.

Does the permit have to be posted at the work site?

Practice varies, and the requirement depends on which authority reaches you. FM Global uses a multi-part form whose second part is posted at the work area as a warning placard for the duration of the work and returned signed at closeout. Some published university permits instruct the holder to post at the work site for the duration. Others state that permits do not have to be posted but must be accessible on request. Where the International Fire Code is adopted, permits and prework check reports have to be available to the fire code official while the work is being done and for 48 hours afterward, which is an availability requirement rather than a posting requirement.

Is a hot work permit the same as a confined space entry permit?

No, and one does not substitute for the other. 29 CFR 1910.146(b) defines a hot work permit as the employer written authorization to perform operations capable of providing a source of ignition, and 1910.146(f)(15) requires that any hot work permit issued for work in a permit space be identified on the entry permit. Issuing an entry permit does not authorize the ignition source, and issuing a hot work permit does not address the atmospheric and rescue requirements of the space. Separately, OSHA stated in a 1997 letter of interpretation that bringing electrical welding equipment into a non-permit confined space does not by itself make it permit-required, as long as the protective measures of Subpart Q prevent a hazard from developing.