Hydraulic Hose Replacement SWMS

Hydraulic hose replacement on HVAC plant — including chiller compressors, cooling tower drive systems, large air handling unit dampers and rooftop package units — exposes workers to stored pressure energy, high-temperature fluid, and pinch points from suspended components. Under WHS Regulation 2025, hose replacement constitutes plant maintenance involving energy isolation, and where the system operates above 50 bar or services pressurised equipment, the work falls within the high-risk construction work definition and triggers mandatory SWMS preparation before work commences. Hydraulic injection injuries from pinhole leaks can inject fluid into tissue at pressures exceeding 200 bar, causing necrosis that requires surgical debridement within hours. This SWMS documents the isolation, depressurisation, hose identification, replacement sequence, and recommissioning controls required to discharge the PCBU's duty under s19 of the WHS Act and the specific plant maintenance obligations under Part 5.1 of the Regulation.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Where feasible, replace failure-prone flexible hoses with rigid steel piping at fixed connection points, eliminating the recurring hose maintenance cycle entirely.
2. 2Elimination — Schedule replacement during planned plant shutdowns to remove the need to work on systems under any residual operating conditions or thermal load.
3. 3Substitution — Specify ISO 18752 performance-rated hose assemblies with integrated burst-protection sleeves to substitute lower-spec hoses prone to pinhole development.
4. 4Engineering — Install lockable isolation valves and pressure bleed points within 1 metre of every hose assembly to permit positive isolation per AS 4024.1603.
5. 5Engineering — Fit accumulator dump valves that automatically discharge stored energy when the isolation lockout is engaged, verified with calibrated pressure gauge reading zero.
6. 6Engineering — Use drip trays, absorbent bunding and ventilated containment around the work zone to capture spillage and prevent oil mist accumulation.
7. 7Administrative — Implement a permit-to-work system requiring isolation certificate, zero-energy verification, and competent person sign-off before any hose disconnection commences.
8. 8Administrative — Conduct documented pre-start brief using this SWMS, confirming hose part number against schematic and verifying hot work exclusion zone if torches are nearby.
9. 9PPE — Wear AS/NZS 2161.3 cut-level D impact gloves, AS/NZS 1337.1 wide-vision goggles, and oil-resistant chemical apron rated for hydraulic mineral oil contact.
10. 10PPE — Use AS/NZS 1715-compliant P2 respirator when working in confined plantrooms where oil mist concentration may exceed 1 mg/m³ workplace exposure standard.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A mechanical services technician is dispatched to a metropolitan hospital plantroom to replace a leaking high-pressure hose on a 1,200 kW screw chiller's hydraulic damper actuator. At the pre-start brief, the supervisor opens this SWMS on a tablet and walks through it with the two-person crew at the plant entry. They identify the specific hazards present — the chiller has been running until 30 minutes prior so residual fluid temperature is approximately 65°C, and the accumulator schematic shows a 3-litre nitrogen-charged unit upstream of the failed hose. Following the controls in sequence, the lead technician isolates the hydraulic pump at the lockable disconnect, applies a personal padlock and tag, then opens the accumulator dump valve and verifies zero pressure on the test gauge over a two-minute settling period. Both workers sign on to the SWMS acknowledging they understand the injection injury risk and have donned cut-level D gloves and wide-vision goggles. Mid-task, they discover the replacement hose part number on the van differs from the schematic by one digit — referring back to the administrative control requiring hose specification verification, they pause work, contact the parts supplier to confirm equivalence, and document the substitution and approval on the SWMS amendment line before proceeding to fit, torque to 45 Nm, and recommission with a controlled pressure ramp.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS 2550 — Cranes, hoists and winches; AS 1418 series

Frequently asked questions