If you work in metal processing, you've probably seen the footage. CCTV inside an aluminium extrusion plant shows a sudden spray of hydraulic oil near the press. Within seconds it becomes a wall of flame racing across the ceiling, and workers run for their lives.

The fire happened in June 2022 at an aluminium plant in the city of Dos Hermanas. Extrusion rigs like this use hydraulics to push the billets through the tooling, and it looks like a hydraulic fitting blew, leading to that initial spray. Industry commentators described it as an overpressure hydraulic fluid line failure. Remarkably, no one was injured in the fire. But the building's roof collapsed and the production line was destroyed.

The incident isn't unique. In California, a fire at an aerospace aluminium forge was traced back to what the fire captain described as a hydraulic line break that may have atomised hydraulic fluid and contacted a hot surface.

For any Australian plant running large presses, shears, cutters or rolling equipment, the lesson is clear. Hydraulic oil at high pressure, near high heat, is a fire waiting for a failure.

Why hydraulic leaks become fires

Hydraulic oil in a drum is hard to ignite. The danger comes from pressure. Extrusion presses and heavy metal-forming equipment commonly run at 200 to 350 bar. When a hose, fitting or seal fails at that pressure, the oil doesn't dribble. It atomises into a fine mist that can travel several metres and burns far more readily than liquid oil.

Put that mist next to a billet heated to around 450–500°C, a furnace, a container heater or an electrical cabinet, and ignition can be almost instant. Because the pump keeps feeding oil into the fire until someone shuts it down, a small failure can become a major blaze very quickly.

The common causes of hydraulic leaks

Most hydraulic failures aren't sudden or random. They build up over months, and they are usually preventable.

Ageing and fatigued hoses. Hoses have a finite service life. Heat, pressure cycling and ozone break down the inner tube and reinforcement over time, often with little visible warning.

Pressure spikes and overpressure. Faulty or incorrectly set relief valves, sticking directional valves and fast valve switching can all create pressure spikes well above a hose's rated working pressure. Every spike shortens its life.

Poor assembly and mismatched components. Incorrect crimp diameters, mixing hose and fitting brands that weren't designed to work together, and fittings assembled by untrained staff are all leading causes of blow-offs at the fitting.

Incorrect torque and vibration. Under-tightened fittings loosen under constant press vibration. Over-tightened fittings crack or damage seats. Either way, the joint will eventually leak.

Heat-damaged seals. O-rings and seals near hot zones harden and crack. What starts as weeping can become a spray.

Abrasion and poor routing. Hoses that rub against steel structures, each other, or moving parts will wear through. Hoses routed too tightly beyond their minimum bend radius fail early.

Contaminated oil. Dirty fluid accelerates wear in pumps and valves, which causes pressure instability and internal damage elsewhere in the system.

How to protect your plant

1. Run a proper hose management program.

Tag every hose with its install date and specification. Set replacement intervals based on duty and environment, not just visible condition. Hoses near hot zones and on high-cycle equipment should be replaced on a schedule, before they fail.

2. Inspect regularly, and inspect properly.

Look for weeping fittings, blistered or cracked hose covers, abrasion, kinks and oil-soaked surrounds. Treat any weep as a warning. Never check for leaks by running a hand along a pressurised hose. A pinhole leak can inject oil under the skin and cause a serious injury.

3. Use qualified people and matched components.

Hose assemblies should be built with matched hose and fitting systems, crimped to the manufacturer's specification, and pressure-tested where appropriate.

4. Check your relief valves and pressure control.

Have relief valve settings verified and look for signs of pressure spikes. If your system is regularly peaking above design pressure, fix the cause rather than replacing hoses more often.

5. Shield and re-route near hot zones.

Fit spray guards and fire-resistant hose sleeves around hoses near billets, containers, furnaces and ovens. Where possible, reroute lines away from heat sources and ignition points altogether.

6. Consider fire-resistant hydraulic fluids.

For presses operating near extreme heat, fire-resistant fluids can greatly reduce ignition risk. They come with trade-offs in seal compatibility, cost and maintenance, so assess them with a specialist like Flotek before switching.

7. Make sure you can stop the oil fast.

Emergency stops should shut down pumps and safely isolate or dump stored pressure in accumulators. Consider automatic pump shutdown on sudden pressure loss or low reservoir level, so a burst line isn't fed for minutes.

8. Plan for the worst.

Review fire detection and suppression around presses. Keep housekeeping tight: oil-soaked insulation, sawdust, rags and ceiling voids all give a fire somewhere to go. Train your team to evacuate immediately rather than stopping to grab belongings or fight a hydraulic fire.

The bottom line

The Spanish plant was lucky. Nobody died. But the building, the production line and months of output were lost, all potentially from a single hydraulic component.

For large metal processing plants, hydraulic reliability isn't only a maintenance issue. It's a fire safety and WHS issue. The cost of a proactive hose and fitting program is tiny compared to the cost of losing a press line, or a person.

Flotek, Victorias leading hydraulic services company,  provides a HSI (Hydraulic System Inspection) program which involves a full inspection of your hydraulic machines on a quarterly basis.  We already help some of Melbourne's largest steel and metal processing plants keep their hydraulic systems safe and reliable. 

Cost is as little as $279 per hydraulic unit.

If you haven't had your press hydraulics assessed recently, now is a good time to talk to us.