Underwater Wet Welding & Oxy-Arc Cutting SWMS
Wet welding and oxy-arc cutting underwater. Electrical safety in seawater, hydrogen embrittlement, underwater fume management. Diver and topside crew coordination per AS 2815.3.
SWMS variants reference your state’s WHS legislation. Instant download after payment.
Underwater wet welding and oxy-arc cutting combine three of the highest-risk activities recognised under Australian WHS law: commercial diving, hot work, and live electrical operations conducted in a conductive seawater environment. Workers perform shielded metal arc welding (SMAW) or exothermic cutting at depth on submerged structures such as wharf piles, vessel hulls, offshore moorings, and intake screens, while exposed to drowning, electric shock, hydrogen explosion in trapped voids, decompression illness, and entanglement. A Safe Work Method Statement is mandatory because this work simultaneously triggers multiple High Risk Construction Work categories under Schedule 1 of the WHS Regulation 2025, and is further regulated under AS/NZS 2299.1 Occupational diving operations and AS 2815.3 for the welder-diver qualification pathway. The SWMS must be prepared in consultation with the dive supervisor, welder-divers, and topside electrical attendant before mobilisation, and reviewed at each pre-dive brief. It documents the engineered controls — particularly the knife switch, polarity, and lockout regime — that prevent fatal incidents recurring in the Australian commercial diving record.
Hazards identified
7 hazards covered, sorted by priority.
Ventricular fibrillation, loss of consciousness underwater, drowning, and fatal cardiac arrest before recovery to surface
Explosive ignition causing barotrauma, ruptured eardrums, fatal lung overexpansion injury, and structural collapse onto diver
Delayed cracking, sudden structural failure of repaired component, third-party injury, and regulatory non-conformance on classed vessels
Type II DCI with neurological deficit, paralysis, permanent disability, and recompression chamber emergency evacuation
Loss of gas supply, communications failure, inability to surface, panic ascent, and arterial gas embolism
Acute pulmonary oedema, metal fume fever, long-term occupational lung disease, and contamination of breathing gas supply
Crush injury from dropped load, propeller strike, severed umbilical, and immediate loss of life support to the diver
Control measures
Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.
- 1Elimination — Where structurally feasible, dewater the work area using a cofferdam or habitat to convert wet welding to dry hyperbaric welding, removing electrical and hydrogen hazards entirely.
- 2Elimination — Replace underwater cutting with mechanical shears or diamond wire sawing on structures where ignition sources cannot be controlled inside enclosed voids.
- 3Substitution — Substitute oxy-arc cutting with exothermic lance only on substrates free of hydrocarbon residues, and use low-hydrogen E7018 equivalent electrodes rated for wet service.
- 4Engineering — Install a topside-operated knife switch (positive-make, positive-break) in the welding circuit, energised only on diver voice command per AS 2815.3 clause 6, with DC straight polarity electrode-negative to reduce diver shock risk.
- 5Engineering — Provide redundant breathing gas via bailout cylinder sized for maximum planned depth and decompression obligation under AS/NZS 2299.1, with continuous voice communications and through-water backup.
- 6Engineering — Vent enclosed voids and confirm gas-free status using submersible gas detection before any arc strike inside box girders, piles, or hull compartments to prevent hydrogen-oxygen ignition.
- 7Administrative — Implement a documented dive plan, JSA, and pre-dive brief signed by the dive supervisor, welder-diver, standby diver, and tender, including emergency recompression and lost-bell procedures.
- 8Administrative — Restrict welder-divers to those holding ADAS Part 3 or equivalent plus AS 2815.3 underwater welder qualification, with current AS/NZS 2299.1 medical and logbook currency verified before mobilisation.
- 9PPE — Issue full-face band mask or helmet with insulated mating surfaces, dry suit with electrical isolation, insulated welding gloves rated for immersion, and weighted boots tested for circuit isolation each shift.
- 10PPE — Provide topside crew with arc-flash rated face shield, insulated gloves for stinger handling, and hearing protection during oxy-arc operations and air compressor running.
Applicable Codes of Practice
Mandates dive supervisor appointment, dive plan, gas supply redundancy, and emergency procedures referenced directly by WHS Regulation 2025 for diving work.
Sets the welder-diver competency, knife switch operation, and underwater electrical safety practices that the SWMS controls must align to.
Governs hot work permits, hydrogen and oxygen accumulation controls, and ignition source management transferable to submerged confined voids.
Regulates the topside vessel, crew certification, and exclusion zones around the dive site to prevent propeller and lift incidents.
High-Risk Construction Work triggered
All tasks are performed by an occupational diver breathing supplied gas underwater, which is the defining criterion for Schedule 1 Category 18 diving work.
Welder-divers operate fully submerged in seawater with umbilical entanglement, gas loss, and unconsciousness risks that directly meet the drowning criterion.
Operations on wharf piles, vessel hulls, and harbour structures occur inside active shipping lanes requiring port traffic and exclusion zone coordination.
The PCBU must prepare, consult workers on, and retain the SWMS for the duration of the high risk construction work plus statutory record period; penalties are substantial and indexed, with the current maximum following the prevailing WHS schedule.
Who this is for
- →Commercial diving contractors on marine infrastructure projects
- →Port authority maintenance and wharf repair crews
- →Offshore vessel hull and mooring repair operators
- →Hydroelectric and water utility intake maintenance divers
What you receive
- ✓Editable DOCX template — Microsoft Word compatible
- ✓State-specific WHS legislation schedule (NSW/VIC/QLD/SA/WA/TAS/NT/ACT)
- ✓Hazard register with risk ratings + hierarchy-of-control mapping
- ✓Worker sign-on register, pre-start checklist, and incident escalation flow
Worked example
On a Tier 2 wharf refurbishment contract, a three-person dive team mobilises to oxy-arc cut corroded sheet pile sections at minus eight metres alongside a working commercial berth. At the pre-dive brief, the dive supervisor opens the Underwater Wet Welding & Oxy-Arc Cutting SWMS on a ruggedised tablet and walks the welder-diver, standby diver, and tender through each hazard line. The team identifies that today's substrate includes coal tar epoxy coating, triggering the toxic fume control, so the supervisor adds an extended surface decontamination step and confirms the bailout cylinder is charged. The tender confirms the topside knife switch is wired electrode-negative and tests the positive-break action with the welder-diver on comms. All four sign the SWMS sign-on register, including the port operations officer who has issued the exclusion zone permit covering the adjacent shipping lane. Twenty minutes into the dive, the welder-diver reports rising bubbles trapped under a horizontal flange — a hydrogen accumulation indicator listed as a high-priority hazard in the SWMS. The supervisor halts cutting, calls electrode safe, and instructs the diver to vent the void with a pry bar before re-striking the arc. The stop-work, control verification, and resumption are logged on the SWMS dynamic risk page, and the amended control is briefed to the afternoon shift before the next dive commences.
Related legislation
- WHS Act 2011 (model)
- WHS Regulation 2025
- AS 2550 — Cranes, hoists and winches; AS 1418 series