Hot-Dip Galvanising Plant SWMS

Hot-dip galvanising operations involve immersing fabricated steel into a kettle of molten zinc at approximately 450°C, preceded by acid pickling and fluxing pre-treatment and followed by quenching, passivation and inspection. The work exposes operators to severe thermal hazards, hexavalent chromium and zinc oxide fume, concentrated sulphuric and hydrochloric acid baths, overhead crane loads, and elevated platforms above the kettle and dip tanks. Under WHS Regulation 2011 r291 and the harmonised WHS Regulation 2025, this constitutes High Risk Construction Work because it involves work at heights above 2m over open process tanks, exposure to substances hazardous to health, and the risk of molten metal explosion from moisture ingress. A documented Safe Work Method Statement is mandatory before any galvanising shift commences and must be reviewed whenever the process, jig design, or workforce changes. This template enables PCBUs to demonstrate consultation, hazard identification and control verification across the full pre-treatment, kettle and post-treatment workflow.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Reject any fabricated article with sealed hollow sections; require vent and drain holes minimum 25% cross-sectional area per AS/NZS 4680 before dipping to eliminate explosion risk.
2. 2Elimination — Remove personnel from kettle-side during automated dip cycles by installing remote jig lowering controls operated from a shielded pulpit station.
3. 3Substitution — Replace hexavalent chromium passivation with trivalent chromium or chromium-free polymer post-treatment systems to remove Group 1 carcinogen exposure pathway.
4. 4Substitution — Use inhibited hydrochloric acid pickling formulations in place of higher-fuming sulphuric blends to reduce airborne acid mist generation.
5. 5Engineering — Install lateral-draught and push-pull local exhaust ventilation over kettle and passivation tanks designed to AS 1668.2 capture velocities, with quarterly extraction performance testing.
6. 6Engineering — Provide engineered guardrails, kettle-edge fall arrest anchor points and grated walkways above all tanks, certified to AS/NZS 1657 for platforms and AS/NZS 1891 for fall systems.
7. 7Engineering — Pre-heat all loads in a dedicated drying oven to above 100°C and verify with infrared thermometer before kettle immersion to eliminate trapped moisture.
8. 8Administrative — Mandate pre-start SWMS sign-on, jig inspection checklist, vent hole verification and crane pre-operational checks per WHS Regulation r291 and Managing Risks of Plant CoP.
9. 9Administrative — Schedule kettle-side rotation limiting continuous exposure to 20 minutes with mandated hydration breaks, supported by heat stress monitoring per the Managing Heat at Work CoP.
10. 10PPE — Issue aluminised proximity suits, chrome leather spats, face shields over P3 respirators, acid-resistant gauntlets and AS/NZS 2210.3 metatarsal safety boots, with health monitoring per WHS Reg Schedule 14.

Applicable Codes of Practice

Worked example

At a regional structural steel galvanising facility, the morning shift supervisor convenes a pre-start brief at the kettle pulpit with two operators, a crane driver and a quality inspector. The SWMS is projected on the toolbox screen and each worker walks through the hazard register, confirming today's job — dipping a batch of fabricated handrail assemblies — has been vent-hole inspected and pre-heated to 110°C in the drying oven. The crew identifies that one assembly has a sealed end cap; the supervisor halts that item and returns it to the fabrication bay, citing the elimination control in the SWMS. Operators sign on electronically, confirming they have aluminised PPE, P3 respirators and that the LEV draught gauge reads within the green band per the engineering control entry. Mid-shift, ambient temperature climbs to 42°C and the heat stress monitor triggers; the supervisor invokes the administrative rotation control, swapping kettle-side personnel every 15 minutes and increasing electrolyte break frequency. When a load swing incident occurs with the overhead crane, work stops, the SWMS is reviewed against the crane operations clause, the anchor inspection is repeated, and a dynamic risk note is added before resumption. The signed document is filed to the site WHS register that evening for the two-year retention period.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Managing the Risk of Falls at Workplaces CoP

Frequently asked questions