The hydraulic pipe burst and sprayed onto the red steel. Did the fire extinguisher in the workshop work properly?

"BANG!!"

 

It wasn't a broken roll, nor a pile-up of steel. It was a high-pressure hose in the hydraulic station of the finishing mill that burst.

 

The oil mist instantly sprayed out and directly smeared onto the red steel that had just been rolled out nearby - "whoosh" - the flame shot up two meters high, black smoke billowed, and the operator grabbed the nearest fire extinguisher and rushed over to extinguish it.

 

Result: The dry powder was sprayed out, but the fire didn't go out, and the oil was still burning.

 

An experienced senior worker shouted nearby: "Change that one! The big one!"

 

A fire blanket was replaced and covered it, and the fire was finally suppressed.

 

Afterwards, when checking the surveillance footage: from the burst hose to the flame shooting up, it only took 8 seconds. From the flame to extinguishing it, it took 3 minutes. However, the cable trays next to the hydraulic station had been deformed by the heat, and the shells of the proximity switches melted. The production was halted for 6 hours.

 

1. Why can't water extinguish oil fires

The most fundamental point is: oil is lighter than water, and water is heavier than oil.

 

When the hydraulic oil catches fire, if you use water to put out the fire - 

 

The water sinks to the bottom of the oil, and the oil floats on the surface and continues to burn. When water is sprayed, the oil surface is disturbed, and the burning area expands instead. Even worse: when the hot red steel (500~800℃) meets water, it instantly vaporizes and expands, carrying oil droplets and scattering them everywhere, effectively throwing the fire elsewhere.

 

Extinguishing oil fires with water = adding fuel to the fire.

 

This is basic physics, but there are people in the steel rolling workshop who actually use water hoses to put out fires.

 

2. Why is the hydraulic station fire particularly dangerous

Compared to ordinary fires, the hydraulic station in the steel rolling workshop has 4 fatal factors:

 

1. High oil temperature, low flash point

When the hydraulic system is working normally, the oil temperature is 60~80℃. When the high-pressure pipeline leaks, the oil mist temperature is even higher. Mineral-based hydraulic oil has a flash point of about 200℃, but the flash point of the oil mist is much lower than that of the liquid oil - when it forms oil mist and encounters the red steel (500℃+), it instantly ignites.

 

2. High pressure, long spray distance

The hydraulic system pressure of the rolling machine often reaches 16~31.5MPa. When the burst hose occurs, the oil is not "flowing" out, but is sprayed at a bullet speed. The spray distance can reach 5~8 meters, covering a large area, and the probability of contact with the red steel is extremely high.

 

3. Close location, with red steel right next

The hydraulic station is often located next to the rolling machine frame, roller track, and live roll - all areas where red steel appears. When the oil is sprayed out, the nearest red steel may be just two meters away.

 

4. Severe chain losses

When the hydraulic station catches fire, not only the oil is burned. The nearby cable trays, sensors, encoders, servo valves, and electrical cabinets are all within the range of the fire. A fire that burns away spare parts costs ten times more than the oil itself.

 

3. What fire extinguisher should be used in the steel rolling workshop (comparison table)

Type of fire

 

Correct fire extinguisher

 

Wrong choice

 

Reason

 

Hydraulic oil/ lubricating oil catches fire

 

Dry powder fire extinguisher (ABC type), carbon dioxide fire extinguisher, fire blanket

 

Water-based type, foam type

 

Water cannot be used to extinguish oil fires; foam has poor effect on hot red steel

 

Fire in electrical cabinet

 

Carbon dioxide fire extinguisher, dry powder

 

Water, foam

 

Water conducts electricity, causing electric shock + equipment short circuit

 

Fire on the surface of red steel/rolling mill

 

Fire blanket coverage, dry sand

 

Water (use with caution), carbon dioxide

 

Water vaporizes and splashes on red steel

 

Water

 

As mentioned above, conductive + steam burn

 

Key judgment criteria: Check the applicable fire category on the fire extinguisher.

 

Class A: Solid substances (wood, fabric) → Common workshop debris

Class B: Liquids or molten solids (oil, grease, asphalt) → Select this for hydraulic oil fires

Class C: Gases → Gas, natural gas

Class E: Electrically charged equipment → Electrical cabinets, motors

Hydraulic stations must be equipped with Class B or ABC fire extinguishers. Those marked only as Class A cannot extinguish oil fires.

 

IV. Correct handling steps for hydraulic station fires

Step 1: Press the emergency stop + cut off the hydraulic pump

It's not about extinguishing the fire first; it's about cutting off the oil source first. As long as the hydraulic pump is running, the oil is still spraying, and the amount you extinguish is exactly the amount it replenishes.

 

Press the emergency stop button (red mushroom head)

Close the manual shut-off valve for the hydraulic station's oil supply

Confirm that the pump has stopped and the system has depressurized (check the pressure gauge returns to zero)

Step 2: Choose the right fire extinguisher and stand at the upwind position

Use ABC dry powder or carbon dioxide fire extinguisher

Stand at the upwind position or the side upwind position, 2-3 meters away from the fire source

Aim at the root of the flame, not the top of the flame

Dry powder fire extinguisher: Pull the pin → Press the handle → Sweep left and right

Carbon dioxide: Wear gloves to prevent frostbite, aim at the root

Step 3: Use fire blanket when the oil volume is large

If the sprayed oil area exceeds the coverage of the fire extinguisher:

 

Use a fire blanket from the upwind direction to cover

Cover tightly, leaving no gaps

Don't lift it to check until the temperature drops

Step 4: After the fire is extinguished, don't relax

Confirm no re-ignition signs (observe for 10 minutes)

Check for any damage to the surrounding cables, sensors, and electrical cabinets

Cover the oil leakage area with dry sand or oil-absorbing cotton, for anti-slip and prevention of secondary fire

Ventilation and smoke removal (oil fires produce toxic smoke containing carbon monoxide and acrolein)

Step 5: After the incident, always check three items

Hydraulic piping system

Reasons for pipe burst investigation (aging/misalignment/loose joints/overpressure)

Peripheral equipment

Cable insulation test, sensor function test, servo valve status

Fire extinguishing system

: Replacement for used fire extinguishers, replacement when pressure is insufficient

V. Oral instructions that can be directly read during the pre-shift meeting

In case of hydraulic station fire, don't panic:

First, stop the pump, then cut off the oil supply, and select the right device.

For dry powder and carbon dioxide, press down directly at the root.

Pouring water on oil fires is suicidal. Using a fire blanket is the safest option.

After extinguishing the fire, stay for ten minutes. Re-ignition is more dangerous than initial ignition.

VI. Fire inspection confirmation form for hydraulic station (printed and attached at the site)

[ ] Hydraulic station entrance is equipped with at least 2 ABC dry powder fire extinguishers (4kg or more)

[ ] Each extinguisher has a pressure pointer in the green zone

[ ] Fire blankets are hung in easily accessible positions (without locks or obstructions)

[ ] Hydraulic pipelines have no leakage or aging cracks (visual inspection weekly)

[ ] The hydraulic station has good ventilation (fan is normal)

[ ] There are no flammable debris piled up within 5 meters of the hydraulic station

[ ] Operators can use fire extinguishers (quarterly drill)

[ ] The emergency stop button of the hydraulic station functions normally

[ ] The replacement cycle of the high-pressure hose is recorded completely (according to the manufacturer's recommendation, usually 2-3 years)

[ ] There are fireproof partitions or fireproof coatings on the cable trays near the hydraulic station

Hydraulic station fires are not "if" but "inevitable" - the high-pressure hose has a lifespan, joints will loosen, and oil temperatures can be abnormal. You can't control when it will explode, but you can control who will extinguish it, what to use to extinguish it, and how to do it.

 

When was the last time you checked those fire extinguishers in the workshop?

 

What type of fire extinguishers are provided in your workshop's hydraulic station? Has anyone actually used them? Share your comments here.