In this module
Objectives covered: LO 3.11.1. By the end you will be able to:
- Identify fire, fume, radiation and electrical hazards in hot work.
- Apply hot work permit and fire watch requirements.
- Store and handle compressed gas cylinders safely.
11.1 Hazards of hot work
- Fire and explosion: sparks travel up to 35 feet (11 m) and can fall through cracks.
- Fumes and gases: metal fumes, manganese, hexavalent chromium (stainless steel), zinc (galvanised steel), and toxic gases from coatings.
- Radiation: ultraviolet and infrared light causes "arc eye" and skin burns.
- Electric shock from arc welding equipment, especially in wet or cramped places.
11.2 Hot work controls
- Move the work to a safe place, or move combustibles at least 35 feet away, or cover them with fire-resistant blankets.
- Issue a hot work permit after checking the area; test for flammable gas where needed.
- Post a fire watch with an extinguisher during the work and for at least 30 minutes after.
- Ventilate or use local fume extraction; respirators where needed.
- Welding screens to protect others; correct filter shade for the welder.
11.3 Compressed gas cylinders
- Store upright and secured with chains; valve caps on when not in use.
- Separate oxygen from fuel gases by 20 feet (6.1 m) or a 5-foot non-combustible barrier rated for 30 minutes.
- Use flashback arrestors on oxy-fuel sets; check hoses for leaks with soapy water, never a flame.
- Never use oxygen to blow dust off clothing or as compressed air.
Standards and rules
- 29 CFR 1910 Subpart Q (1910.251 to 1910.255): welding, cutting and brazing; 1910.253 oxy-fuel gas.
- NFPA 51B: fire prevention during hot work. AWS / ANSI Z49.1: safety in welding.
Bangladesh industry example
Many factory fires in Bangladesh start during welding repairs near fabric, foam or chemical stores. In one Gazipur sweater factory, welding sparks fell through a floor opening onto yarn below and started a fire. The company now requires a hot work permit, fire blankets over openings, and a fire watch who stays 30 minutes after work ends.
Learning Check
Answer these two questions to check your understanding. You can try again as many times as you like.