Hot Work Permits – Procedure

Authorization

Only an authorized person may issue a Hot Work permit. The person authorizing the permit must personally inspect the area for fire safety before signing.

Duration

The permit is valid only for the period specified on the permit, not to exceed one shift duration. If work is to continue during a shift change, a new permit is issued at the shift changeover. Should work be required beyond the specified duration, then a new permit is also issued.

Application

A Hot Work permit is required regardless of whether it is being performed by NSC employees, contractors, or visitors.

The permit must be completely filled out before work is approved.

Wherever possible, Hot Work will be conducted in a maintenance shop or other properly equipped location such as a contractor area where a plant risk assessment has determined that no permit is required.

Work Area Precautions

Prior to issuing a Hot Work Permit:

General – Remove all combustible material within a radius of 35 feet (ca. 11 meters).
Where possible, barriers are placed around the work to confine sparks and prevent exposure to welding flash during arc welding.
Floors – Where combustible materials are present, floors must be swept and cleared for a radius of 11 meters (ca. 36 feet). Combustible floors are kept wet, covered with damp sand, or protected by fire-resistant shields. Where floors have been wet down, personnel operating welding or cutting equipment are to be protected from electric shock.
Ducts – Ducts and conveyor systems that could carry sparks to distant combustibles are to be protected or shut down for the duration of the permit.
Noncombustible Walls – If welding is to be done on a metal wall, partition, ceiling or roof, precautions will be taken to prevent ignition of combustibles on the other side. If the combustibles on the far side cannot be relocated, a fire watch will be posted.
Pipes – If the Hot Work site is close enough to pipes or other metal that are in contact with combustible walls, close enough to cause ignition by conduction, no permit can be issued.
Lines containing material that produce dangerous fumes when heated are to be cleaned prior to Hot Work starting.
Containers, used drums and other items with cavities need to be thoroughly cleaned and disconnected from pipe work.
All containers or other hollow spaces are to be vented.
At heights – The area below the Hot Work site is roped off and posted if sparks can fall to the ground. Where possible, cover floor grills with a protective barrier to prevent falling debris.
Where there is a risk of dust explosions:
Remove dust from overhead area’s walls, equipment, and floors

Note that the radius of 35 feet (ca. 11 meters) could encompass adjacent property; these guidelines still apply in these cases.

Prohibitions Hot Work is not allowed if –

Metal in contact with a combustible structure, or Hot Work on metal walls or partitions with a combustible covering.
In sprinklered building where these are not working.
In areas near the storage of large quantities of exposed, readily ignitable materials
In the presence of explosive atmospheres (mixtures of flammable gases, vapors, liquids, or dusts with air),

Fire Watch

Most Hot Work permits will need a fire watch.

A fire watch is needed in any case if:

An appreciable amount of combustibles are within 11 meters from the Hot Work.
A large amount of easily ignited combustibles are present further than 11 meters from the Hot Work.
Wall or floor openings within the 11-meter radius expose combustibles in adjacent areas. These openings include concealed spaces in walls or floors.

The assigned fire watch signs the permit form when these provisions have been met, indicating acceptance of the permit and his responsibilities. The fire watch has the authority to stop Hot Work at any time.

The fire watch will have the appropriate fire extinguisher available, and be trained in its use. He will know the site alarm procedure, in case a fire is started that he cannot put out. He will possess the skills to identify fire hazards.

The fire watch will remain on the job site for 30 minutes after completion to watch for post-ignition of combustibles. Once complete, the fire watch reports to the authorized person to sign-off on the Permit, stating that the area is safe.

Monitoring

Hot Work within rated areas, or anyplace where the presence of flammable vapors or gases is possible, requires LEL monitoring. Arrangements must first be made to prevent fires by:

isolating and purging process equipment where necessary,
reducing the risk of emissions from reliefs, vents, sample points or drains, control of other work in the area,
removal of combustible material as described under Precautions.

Procedure for completing a Hot Work Permit

Both the Department Supervisor and the Hot Work supervisor must personally inspect the job before authorizing the permit.

Hot Work inside a confined space

Compliance with the Confined Space Entry procedure is a prerequisite.

All Hot Work performed inside a confined space will be performed using a supplied air respirator
Hot work to be performed inside a space that may contain explosive materials requires continuous gas monitoring as close as possible to the area of flame. For some materials continuous monitoring is not reliable. Laboratory analysis is then required.
Gas cylinders and electric-welding machines will be outside the confined space. Gas powered welder swill be out of doors in a well-ventilated area.
Ventilation for the confined space will be located to remove fumes and smoke from the Hot Work and keep the concentration of fumes in the breathing zone within safe limits.

Hot Work Permits – Procedure