Vessel / Tank Internal Cleaning SWMS

Internal cleaning of process vessels, storage tanks and reactors is one of the highest-risk activities undertaken across Australian industrial, food, petrochemical and water sectors. The work involves entry into a confined space that has typically contained product residues, sludge, vapour or oxygen-deficient atmospheres, and requires interaction with mechanical agitators, manways and inerting systems. Under WHS Regulation 2011 r291 the activity is classified as High Risk Construction Work where it occurs on a construction project, and under AS/NZS 2865:2009 every entry must be authorised by a written permit supported by a documented Safe Work Method Statement. The combined hazards of atmospheric contamination, chemical residue, restricted egress and energy isolation mean a SWMS is mandatory before any person breaks the plane of the vessel. This template provides the prepared, CIH-reviewed control framework that confined-space entry supervisors, stand-by attendants and entrants must apply at every shift, every entry, every vessel.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Where possible, clean vessel externally via CIP (clean-in-place) spray balls, robotic crawlers or hydroblast lances eliminating the need for human entry entirely.
2. 2Elimination — Schedule cleaning immediately after planned shutdown drain-down so residue volume and atmospheric hazard load are minimised before any entry consideration.
3. 3Substitution — Replace solvent-based cleaning agents with low-VOC aqueous detergents or biodegradable degreasers compliant with AS/NZS 2243.2 to reduce flammable and toxic vapour generation.
4. 4Substitution — Substitute manned entry with remote-operated tank cleaning machines (Gamajet, Scanjet) where vessel geometry and residue permit no-entry cleaning.
5. 5Engineering — Apply full lockout-tagout to all inlets, outlets, agitators and heating coils per AS 4024.1603, install blind flanges or double-block-and-bleed isolation verified by entry supervisor.
6. 6Engineering — Provide forced mechanical ventilation delivering minimum 20 air changes per hour with intrinsically safe ducted fans, continuous four-gas monitoring (O2, LEL, CO, H2S) with alarms at 19.5%, 5% LEL and TLV thresholds.
7. 7Administrative — Issue confined space entry permit per AS/NZS 2865:2009 valid one shift maximum, with named entrant, stand-by attendant, rescue plan, communication method and pre-entry gas test recorded on permit.
8. 8Administrative — Conduct pre-start briefing using this SWMS, verify training currency for confined space entry (RIIWHS202E), and rotate entrants every 30 minutes to manage heat and concentration fatigue.
9. 9PPE — Supplied-air breathing apparatus (SABA) with escape cylinder or SCBA per AS/NZS 1716, chemical-resistant Type 3 coverall, nitrile gauntlets, full-face mask and harness with retrieval line to tripod-mounted winch.
10. 10PPE — Intrinsically safe head torch, hearing protection where ventilation exceeds 85 dB(A), and anti-static footwear when flammable residue is present per AS/NZS 2210.5.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

At a regional dairy processing facility, a 12,000 litre stainless steel cream silo is scheduled for quarterly internal CIP failure inspection and manual residue removal. The confined space entry supervisor opens the shift with a pre-start brief using this SWMS, projected on a tablet at the manway. She walks the two entrants and the stand-by attendant through each of the seven hazards, pausing on flammable vapour because a CIP caustic-acid cycle was incomplete the prior shift. The team agrees to extend forced ventilation from the standard 30 minutes to 90 minutes and re-test LEL before entry. Isolation is verified — agitator locked out, CIP supply blanked, steam coil drained — and each isolation point is photographed and attached to the permit. The four-gas monitor logs 20.9% O2, 0% LEL, 0 ppm H2S; permit is signed and entry proceeds with SABA on supplied air. Forty minutes in, the attendant observes the entrant's voice slowing on comms — a SWMS-prompted heat stress indicator — and initiates the planned 30-minute rotation. The relief entrant signs on against the same permit, the original entrant rehydrates in the cool zone, and cleaning completes without incident. The signed SWMS, permit and gas log are filed to the plant's WHS register for the mandatory retention period.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS 2865 — Confined spaces

Frequently asked questions