Vapour / Wet-Media Cabinet Blasting SWMS

Vapour and wet-media cabinet blasting is enclosed abrasive blasting carried out inside a sealed cabinet, where the operator works from outside through gloved ports and the abrasive is delivered in a water slurry that suppresses dust. It is not ordinarily high risk construction work — the operator is outside an enclosed unit and the dust is contained within it — so a SWMS is prepared to manage the substance and plant hazards under the WHS general duties rather than as construction HRCW. Where, however, a walk-in blast room is entered, the confined-space provisions and AS 2865 apply and the work becomes confined-space work. The defining hazard is still crystalline silica: blasting parts or castings that contain at least 1% crystalline silica, or using a silica-bearing media, is processing a crystalline silica substance, which is controlled and, where assessed as high risk, requires a silica risk control plan, with exposure managed against the respirable crystalline silica workplace exposure standard of 0.05 mg/m³. The wet method greatly reduces airborne dust, but the controls depend on the cabinet's integrity: a torn glove, a failed seal or an open door during operation breaks containment and exposes the operator. Slurry and wastewater carry the silica and any heavy metals from old coatings and must be managed as controlled waste, while media additives, noise and the moving plant inside the cabinet complete the hazard profile. The SWMS controls cabinet integrity, slurry waste, noise and plant, with SafeWork NSW as the regulator.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Specify silica-free media and components so no crystalline silica is processed in the cabinet
2. 2Substitution — Substitute a non-silica abrasive (garnet, glass bead, ceramic) and water-based wet media for silica sand
3. 3Engineering — Sealed cabinet with extraction and a viewing window, maintained to keep the operator outside the dust enclosure
4. 4Engineering — Slurry capture, settlement and filtration so wastewater is treated and silica/metal solids are collected as controlled waste
5. 5Engineering — Interlocks that stop blasting when the door is open or a glove breach is detected
6. 6Administrative — Daily integrity check of gloves, seals and the door, and a silica risk control plan where processing is high risk
7. 7Administrative — Confined space entry permit and AS 2865 controls whenever a walk-in blast room is entered
8. 8Administrative — Health monitoring for silica and, where leaded coatings are blasted, for lead
9. 9PPE — P2/P3 respiratory protection at the cabinet, upgraded to air-supplied for any walk-in blast-room entry
10. 10PPE — Gloves, eye protection and hearing protection for the operator

Applicable Codes of Practice

Worked example

At 8:00 am a workshop operator at Forge Surface Solutions starts a batch of cast-iron parts in a wet-media blast cabinet. Before loading, he runs the daily integrity check the SWMS requires: the gloves are inspected for tears, the door seal and viewing window are sound, and the slurry-capture tank is within level. Because the castings carry an old chromate primer and the media is silica-bearing, the job is treated as processing a crystalline silica substance with a heavy-metal component, so a silica risk control plan applies and he wears a P3 respirator at the cabinet as a backup to containment. He blasts through the gloved ports with the cabinet sealed; when a glove shows a small split mid-batch, the door interlock and his check catch it and he stops and replaces the glove before continuing. The silica- and chromate-laden slurry runs to the settlement and filtration unit, and the collected solids are drummed as controlled waste rather than tipped to the drain. Later a part needs hand-finishing in the walk-in blast room; that entry is done only under a confined-space permit with ventilation and an attendant, to AS 2865.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Abrasive Blasting Code of Practice
• Managing Risks of Hazardous Chemicals in the Workplace Code of Practice

Frequently asked questions