Hot Work - Welding & Cutting SWMS

Hot work covers welding (MMAW, MIG/MAG, TIG), oxy-fuel cutting, plasma arc cutting, grinding on ferrous and coated substrates, thermal lancing and brazing. The work generates temperatures exceeding 3,000°C at the arc, ultraviolet and infrared radiation, molten metal spatter travelling up to 10 metres, and a complex fume plume containing metal oxides, ozone, nitrogen oxides and — where coatings are present — hexavalent chromium, cadmium or isocyanate breakdown products. Ignition of nearby combustibles, oxygen displacement in confined areas, LPG/acetylene cylinder failure and arc-eye injuries are all foreseeable outcomes without disciplined controls.

Under the Work Health and Safety Regulation 2025 (NSW), hot work in areas that may contain a flammable atmosphere or that impose artificial extremes of temperature is high risk construction work under section 291. Section 299 therefore requires a Safe Work Method Statement prepared before work commences, applying the hierarchy of controls in section 36 and consulting workers under section 47 of the WHS Act 2011 (NSW).

Hazards identified

12 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Eliminate hot work where feasible by relocating fabrication to a purpose-built workshop, or substitute with cold cutting methods (mechanical shears, hydraulic cutters, cold saws) — the first control required by section 36 of the WHS Regulation 2025 (NSW).
2. 2Where hot work must proceed on site, issue a written Hot Work Permit valid for the shift only, following AS 1674.1-1997 (Safety in welding and allied processes — Fire precautions), including atmospheric testing of any space that may contain flammable vapour.
3. 3Test the atmosphere with a calibrated 4-gas monitor before and continuously during work in any space capable of accumulating vapour; do not commence if LEL exceeds 5% or O₂ is outside 19.5–23.5%, in line with AS/NZS 2865:2009 for confined spaces.
4. 4Remove or shield combustibles within a 11-metre radius (AS 1674.1); provide non-combustible spark blankets to AS/NZS 4836:2023 and maintain a trained fire watch during work and for at least 60 minutes after completion.
5. 5Control welding fume at source using on-torch fume extraction or Local Exhaust Ventilation designed to capture at the arc; supplement with general dilution ventilation for enclosed areas. Assess exposure against the Workplace Exposure Standards published by Safe Work Australia.
6. 6Manage coated substrates: identify lead, cadmium, chromate primers and asbestos-cement prior to any cutting/grinding. For silica-containing materials use tool-integrated water suppression or on-tool extraction (H-class) per the SafeWork NSW Code of Practice — Managing the risks of respirable crystalline silica.
7. 7Weld return leads directly to the workpiece; inspect leads and holders each shift; use RCD-protected supply and voltage-reduction devices on MMAW sets in electrically hazardous locations, complying with AS 1674.2-2007 (Electrical) and AS/NZS 3012:2019.
8. 8Secure compressed gas cylinders upright with valve protection, use flashback arrestors on both fuel and oxygen lines at regulator and torch, and store per AS 4332-2004 and the Dangerous Goods (Road and Rail Transport) requirements.
9. 9PPE: welding helmet to AS/NZS 1338.1:2012 with correct shade for process/current; flame-resistant leather jacket, gauntlets and spats to AS/NZS 2210.3; P2/P3 respirator or PAPR to AS/NZS 1716:2012 selected per AS/NZS 1715:2009; hearing protection to AS/NZS 1270:2002.
10. 10Hot work in confined spaces requires a separate Confined Space Entry Permit under section 76, continuous atmospheric monitoring, forced ventilation and a stand-by attendant per AS 2865:2009.
11. 11Schedule hot work outside peak thermal load where practicable; implement work/rest cycles and hydration for heat stress; screen workers on manganese-related medications and provide health monitoring under section 435 for lead and chromium (VI) exposure.
12. 12All welders and hot work operators hold White Card (CPCCWHS1001) plus process-relevant competency (e.g. AS 1796 certification where applicable). Consult workers under section 47 of the WHS Act 2011 (NSW) during SWMS development and review the SWMS under section 302 if controls fail, incidents occur or the work method changes.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A mechanical services contractor is engaged to tie in new chilled-water pipework at a food processing facility in Wetherill Park. The work involves MMAW welding and oxy-cutting on carbon steel pipe located in a plant room adjacent to ammonia refrigeration lines and above a suspended acoustic ceiling containing dust and cabling. Before mobilisation, the contractor prepares this SWMS, isolates the ammonia system with the site engineer, conducts a 4-gas atmospheric test, clears combustibles within 11 metres, installs welding blankets to AS/NZS 4836, positions a dedicated fire watch with a 9 kg dry-chemical extinguisher, and runs on-torch fume extraction ducted outside the plant room. A Hot Work Permit is issued shift-by-shift, workers sign on to the SWMS under section 47 consultation, and the fire watch remains for 60 minutes after the final cut. The SWMS is reviewed under section 302 when the scope extends to overhead welding on the following shift.

Related legislation

• Work Health and Safety Act 2011 (NSW) — sections 19, 31, 32, 47
• Work Health and Safety Regulation 2025 (NSW) — sections 36, 76, 291, 299, 302, 435
• Protection of the Environment Operations Act 1997 (NSW) — fume and air emissions
• Environmental Planning and Assessment Act 1979 (NSW) — construction consent conditions
• Dangerous Goods (Road and Rail Transport) Act 2008 (NSW) — compressed gas transport
• Explosives Act 2003 (NSW) — where thermal lancing or exothermic cutting is used

Frequently asked questions