Tank and Vessel Entry — Safe Work Method Statement
Safe Work Method Statement for entry into tanks and vessels including atmospheric testing, isolation, and rescue procedures in compliance with the model WHS Regulations.
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Tank and vessel entry is among the most hazardous confined space scenarios in Australia, and has been responsible for multiple fatal incidents including secondary fatalities where would-be rescuers have entered without adequate protection. The model WHS Regulations Part 4.3 mandates a full suite of controls: a confined space entry permit, atmospheric testing with calibrated multi-gas instruments, complete isolation of all pipework and energy sources using physical blanks or double-block-and-bleed, a standby person in continuous communication with the entrant, and a documented rescue plan with tested rescue equipment available at the point of entry.
Tanks and pressure vessels present specific hazards based on their prior contents. Tanks that have stored hydrocarbons, chemicals, or fermentation products may retain toxic gases including hydrogen sulphide (H₂S), carbon monoxide, or solvent vapours, as well as oxygen-depleted atmospheres from bacterial decomposition. Tanks involved in food or chemical processing may also have residual cleaning chemicals or fumigants. A full process hazard review of the tank's history should inform the atmospheric testing regime and any additional controls required before entry is permitted.
Atmospheric monitoring must be continuous during entry using personal gas monitors or fixed-point instruments capable of detecting oxygen percentage, combustible gases (% LEL), carbon monoxide (ppm), and hydrogen sulphide (ppm). The entry permit's atmosphere testing results must be recorded, with readings compared against the action levels specified in the Safe Work Australia Code of Practice: Confined Spaces. Natural ventilation alone is rarely sufficient for tank entry — mechanical forced ventilation using an intrinsically safe fan is standard practice.
When customising this template, document the tank identifier and dimensions, the prior contents and last cleaned date, the isolation method and energy sources isolated, the ventilation setup and airflow rate, the rescue tripod and harness configuration, and the hospital and emergency contact numbers. Workers must never enter a tank to rescue a collapsed colleague without confirming the atmosphere is safe and wearing SCBA.
This SWMS is applicable in all Australian states and territories. Victorian users should also comply with OHS Regulations 2017 Part 5.3.
Personal Protective Equipment
High Risk Construction Work Types
- •Work in confined spaces
- •Work involving hazardous atmospheres
Risk Assessment
1.Isolation and Lock-Out/Tag-Out (LOTO)
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Inadvertent energisation or introduction of hazardous substances | Catastrophic | Apply full LOTO procedure: isolate all energy sources (electrical, pneumatic, hydraulic, chemical), fit personal locks and tags to each isolation point, drain and de-pressure all lines connected to the vessel, and verify zero-energy state with multi-point testing. Maintain an isolation register and confirm all workers have applied their personal lock before any person approaches the entry point. Assign a designated Isolation Authority who holds the master isolation certificate. | Low | Permit-to-Work Issuer / Site Supervisor |
| Failure to identify all energy sources | High | Conduct a pre-entry P&ID (Piping and Instrumentation Diagram) review with the asset owner to identify every inlet, outlet, vent, drain and instrumentation point. Mark up an isolation plan drawing, physically walk the line to confirm each isolation, and have a second person verify the completed isolation before entry is permitted. | Low | Site Supervisor / Permit Issuer |
2.Atmospheric Testing
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Oxygen-deficient or oxygen-enriched atmosphere causing asphyxiation or fire | Catastrophic | Test atmosphere at entry point and at multiple depths (top, middle, bottom) using a calibrated 4-gas monitor (O2, LEL, CO, H2S) before entry and continuously during work. Acceptable ranges: O2 19.5–23.5%, LEL <5%, CO <25 ppm, H2S <1 ppm. If readings are outside limits, purge with fresh air, re-test, and only permit entry when results are within acceptable range. Maintain continuous monitoring with audible/visual alarms throughout the task. | Low | Confined Space Standby Person / Entry Supervisor |
| Toxic gas release during entry from residues | Catastrophic | Review vessel contents history and obtain Safety Data Sheets for all previous materials. Carry out pre-purge with inert gas if flammable residues are present, then displace with fresh air. Entrants wear supplied-air respirators until 3 consecutive clear atmospheric readings are achieved at 5-minute intervals. Keep standby person at entrance with rescue equipment on standby at all times. | Moderate | Entry Supervisor / Safety Officer |
3.Entry and Egress
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Worker unable to self-rescue or retrieve due to structural layout | Catastrophic | Fit each entrant with a full-body safety harness attached to a tripod-mounted mechanical retrieval device positioned over the entry point. Standby person holds the retrieval line and maintains verbal or visual contact at all times. If contact is lost for more than 30 seconds, initiate rescue plan immediately. Entrants must never progress further than the retrieval length allows. | Moderate | Standby Person / Entry Supervisor |
| Slips, trips, and falls on wet or corroded internal surfaces | High | Inspect internal surfaces by camera before entry. Provide non-slip temporary walkway boards or grating where surfaces are wet or corroded. Workers wear slip-resistant footwear rated for the chemical environment. Lighting of at least 200 lux (intrinsically safe) must be deployed inside the vessel before entry. | Low | Entrant / Site Supervisor |
4.Work Activities Inside the Tank
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Heat stress in hot or poorly ventilated vessels | High | Measure Wet Bulb Globe Temperature (WBGT) inside the vessel before and during entry. Implement work-rest schedule: maximum 20 minutes work with 40 minutes rest if WBGT exceeds 28°C. Supply cooled forced ventilation. Workers must be monitored for signs of heat illness by standby person. Provide cool drinking water and electrolyte replacement immediately outside the entry point. Rotate workers and maintain an entry/exit log. | Moderate | Entry Supervisor / Safety Officer |
| Ignition of flammable residues during cleaning or grinding | Catastrophic | No hot work (grinding, welding, cutting) permitted inside the vessel until LEL reading is 0% on a calibrated gas monitor. Issue a separate hot work permit if hot work is required. Use only intrinsically safe or air-powered tools for routine cleaning. Remove all flammable residues and wash down with water before work commences. Conduct atmospheric test immediately before each work session. | Moderate | Permit Issuer / Entrant |
5.Emergency Rescue
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Delayed rescue of incapacitated entrant | Catastrophic | Establish a written emergency rescue plan before entry commences, including roles, equipment locations, emergency services contacts, and hospital route. Conduct a toolbox talk covering the plan with all workers. Standby person must remain at entry point with retrieval device, fully operational at all times. A second standby person must be available to call 000 while retrieval is in progress — no single standby person may enter to rescue without backup. Rescue equipment (SCBA, stretcher, first aid kit) must be staged within 5 metres of the entry point. | Moderate | Entry Supervisor / Standby Person |
Relevant Codes of Practice
Worker Acknowledgement
By signing below, I confirm that I have read, understood and agree to comply with this Safe Work Method Statement.