Hot Work

"Hot work" is defined as any work that produces a source of ignition such as burning, welding, cutting, brazing, soldering, grinding, chipping, using heat guns, thawing pipes, or using fire- or spark-producing tools that may ignite flammable and/or combustible materials in the area of hot work activities. A few examples of primary business operations where hot work typically is most relevant includes, oil/gas drilling and refineries; chemical plants; marine terminals and shipyards; metalworking; plumbing; heating, ventilation, and air conditioning (HVAC); and scrap yards.

The National Fire Protection Association (NFPA) reports that between 2000 and 2014, there were 4,440 structure fires per year involving hot work, 12 civilian deaths and 208 civilian injuries per year from these fires, $287 million in direct property damage per year, and five firefighter fatalities (between 2001 and 2015). These statistics do not include near-miss fire events from improper hot work activities.

The risk with hot work is high because it introduces an ignition source as a hazard. Therefore, it is important to ask oneself if there is another alternative to conducting hot work. By avoiding hot work, one minimizes or eliminates the associated risks.

Hazards with hot work are most frequently related to fire and explosion hazards. Other hazards include those associated with welding, cutting, brazing and grinding. However, be aware that exposure to welding arcs and welding fumes can result in serious and disabling long-term health injuries.

A great way to determine the hazards of hot work is through creating a job hazard analysis (JHA). JSABuilder is a JHA Software that assists in the creation of job hazard analyses; also known as job safety analyses (JSA), and activity hazard analyses. In JSABuilder, users can identify hazards and determine the safe procedures and controls needed to perform the hot work safely.

Hot work has the potential to unite all three parts of the fire triangle: oxygen, fuel, and an ignition source. Oxygen is in the ambient air. Fuel includes anything that can be ignited including the following:

  • Construction materials such as wood, plastic, insulation, and roofing materials; including those in concealed spaces.
  • Flammable and combustible liquids or gases such as fuel, paint, and cleaning solvents.
  • Simple combustibles such as rags, paper, cardboard, lumber, and furnishings.

Ignition results when a fuel is ignited by a sufficient heat source. Ignition can occur by direct or indirect application of heat. Direct application of heat includes cutting, burning, and welding. Indirect application includes sparks travelling to a distant source and heat conducted through metal surfaces to fuel sources on the other side.

There are various definitions of what constitutes a flammable or combustible liquid. In 29 Code of Federal Regulations (CFR) 1910.106(a)(19), the Occupational Safety and Health Administration (OSHA) defines a flammable liquid as having a flashpoint at or below 199.4 degrees Fahrenheit (°F) (93 degrees Celsius [°C]). OSHA further subdivides flammable liquids into four categories (Category 1 through 4) based on flashpoints and boiling points as summarized in 29 CFR 1910.106(a)(19)(i through iv).

In NFPA 30, a flammable liquid is defined as a liquid whose flash point does not exceed 100°F, when tested by closed-cup test. A combustible liquid is defined one whose flash point is 100°F or higher, also when tested by closed‐cup methods. These broad groups are further classified into six sub-classes (Class IA, IB, IC, II, IIIA, and IIIB) based on flashpoints and two sub-classes based on boiling points (Class IA and IB only).

Companies that conduct hot work activities need to have a Hot Work Program that is specific to their facility. The Hot Work Program should be in writing, require an inspection of the work area before the start of work, and have a written permit signed to indicate that all phases of the work have been inspected and approved.

A resource to use in developing a Hot Work Program is NFPA 51B "Standard for Fire Prevention During Welding, Cutting, and Other Hot Work" (2019). In NFPA 51B, a process to reduce hazards from hot work is "Recognize, Evaluate, and Control", which is summarized as follows:

  • Recognize - Determine if fire risks exist before starting hot work.
  • Evaluate - Determine if hazards are present, especially hazards that can fuel a fire (flammable and combustible liquids or gases and simple combustibles).
  • Control - Take appropriate steps to eliminate or minimize the hazards.

NFPA 51B is required by reference and compliance is not optional. NFPA 51B is referenced in 29 CFR 1910 Subpart Q "Welding, Cutting, and Brazing", and NFPA 1 "Fire Code" requires compliance with NFPA 51B in Chapter 41 (2018 edition).

In using NFPA 51B and applicable regulations to develop a Hot Work Program, the safety person or professional (designated as a Supervisor for purposes of this article) who will be heading up development of the program should make sure that all necessary precautions are discussed in the program. First, the Supervisor should evaluate whether there are other alternatives to conducting the hot work. If so, the work should be conducted using those safer alternative methods. If there are no alternatives to conducting the hot work, then it should be evaluated whether the hot work could be moved to and conducted in a safer location (i.e, one where there are less or no flammable and/or combustible materials).

Once it has been determined if and where hot work is to be conducted, the type(s) and location(s) of safety equipment should be evaluated. Safety equipment and other factors to evaluate in developing a Hot Work Program include:

  • Does the facility have fire sprinklers in the hot work location? If so, are the sprinklers in that location in service? If fire sprinklers are not working, hot work should not be permitted except under very special circumstances and with extra measures of protection. (Note: it may be necessary to cover individual sprinkler heads in the hot work area during the duration of hot work to prevent accidental activation. This should be identified and discussed in the Hot Work Permit).
  • Does the facility have smoke or heat detectors in the hot work area? If so, are the detectors in good working order? (Note: it may be necessary to cover smoke detectors in the hot work area during the duration of hot work to prevent false alarms. This should be identified and discussed in the Hot Work Permit).
  • Does the facility have fire extinguishing equipment readily available and accessible throughout the hot work area? Such equipment may consist of pails of water, buckets of sand, a hose, or portable extinguishers, depending upon the nature and quantity of the combustible material exposed. Are the portable fire extinguishers of the correct type? Is there enough fire extinguishing equipment to cover the hot work area? Is there enough backup fire extinguishing equipment for use during hot work?
  • Does the facility have fire-retardant tarps or thin sheets of metal to cover combustible and ignitable materials within and near the hot work area?
  • Does the facility have fire alarms located near the hot work area? Are the fire alarms readily located in case of need to activate?
  • Have the employees who will be conducting the hot work been trained to understand what hot work is, and the procedures that need to be followed before, during, and after the hot work is completed? Do the employees know where and how to sound the alarm if needed? Are the employees trained in using the type(s) of fire extinguisher(s) available in the hot work area?

The Hot Work Program should provide sufficient detail on the hot work area to be inspected. Per NFPA 51B and OSHA, flammable and combustible materials should be cleared in at least a 35-foot radius around the hot work area if the hot work cannot be moved to an area free of combustibles. If all the fire hazards cannot be removed within that radius, then guards (such as fire-resistant tarpaulins or metal shields) should be used to confine the heat, sparks, and slag, and to protect the immovable fire hazards.

Floors should be swept clean of combustibles and combustible floors should be wet down or covered with damp sand or fire-resistant sheets. Fire-resistant tarpaulins should be used to cover openings in the floors, walls, and ceiling, and suspended beneath the work if hot work is conducted on walls, ceilings, or open-rack flooring.

A flammable gas meter may be used to determine whether or at what concentration flammable gases may be present. If the meter reads above zero, the hot work should not be allowed unless measures are taken to mitigate the source(s) of the flammable gases and subsequent meter readings are zero.

Any hot work conducted in confined spaces should first follow confined space entry procedures. The confined space atmosphere should be monitored during the hot work to ensure sufficient oxygen levels for the workers, and that flammable gases are not present. If vapors need to be purged from the confined space before entry, sufficient time should elapse after purging and the airspace monitored with a gas meter to verify zero readings before initiating the hot work.

Lockout/tagout procedures need to be followed where appropriate, depending on the type of work being conducted. LOTOBuilder is an online tool that can be used to help get a lockout/tagout program started and create lockout/tagout procedures.

Another important part of the safety setup is the fire watch. The only duty of the fire watch person is to scan the hot work area looking for potential fires or hot spots. The fire watch should have fire extinguishing equipment and a means of direct communication to reach emergency service personnel. The fire watch should be trained on using the extinguishing equipment and the procedures for notifying emergency response personnel.

Fire extinguishing equipment should be the correct type for the materials present in the area, and be of large enough capacity to be useful if there is a flare-up, only after the fire department has been notified. In some instances, the fire watch person may also act as the air monitor, using a meter to monitor the air for oxygen levels and the presence of flammable/combustible gases. Otherwise, a separate designated authorized air monitor person may be in the hot work area, in addition to the hot work operators and the fire watch.

Per NFPA 51B, the fire watch must remain in the hot work area for a minimum of 60 minutes after completion of hot work to monitor for smoldering fires. The fire watch could be required to remain in the hot work area longer than 60 minutes depending on the condition of the hot work area. Under OSHA 29 CFR 1910.252(a)(2)(iii)(B), a fire watch must remain in the hot work area for a minimum of 30 minutes after completion of welding or cutting operations.

To document that all necessary steps will be and have been taken during hot work activities in an area, a written Hot Work Permit is prepared and issued by the Supervisor or designated permit authorizing person. The Hot Work Permit is a formal written system and is an extension of the safe system of work. The Hot Work Permit system is a means used to prevent fires or explosions, and will specifically detail the work to be carried out, how and when it is to be done, and the precautions to be taken.

The Permit helps the Supervisor or other permit-authorizing person, the hot work operator(s), and the fire watch to identify and recognize potential hazards associated with hot work in the specific work area. OSHA requires Hot Work Permits in areas where hazardous materials are stored and cannot be removed, or in areas where flammable atmospheres could exist. It is important for the employer to have a hot work program that covers hot work requirements, including permits. The Hot Work Permit should be developed so that it provides facility personnel with the specific information needed for the facility. When preparing a Hot Work Permit, one needs to be specific about the work being conducted and the object(s) on which the work is being conducted. A copy of the Permit could be posted in the Hot Work Area for easy access by the hot work personnel.