Industry and Investment NSW has issued a safety alert after the “catastrophic failure” of hydraulic isolation valves on a mine’s longwall system, as a result of high pressure.
The hydraulics were over-pressurised, causing the failure and leading to the release of fluid.
Fortunately, no one was injured in this incident, but the Department has warned that the uncontrolled release of high-pressure hydraulic fluid has caused fatalities in the past.
In August 2006, a contractor was killed when taking fluid samples from a large hydraulic system used to power longwall machinery at an underground coal mine in NSW.
There were also several serious injuries caused by the same problem across the state in 2005.
According to the Department, a pump station was shutting down regularly as a result of over-pressure trips.
When investigated the trips, two tradesmen isolated two of the three pumps and the face delivery line.
However, when the third pump was started, the pressure rose quickly throughout the remaining hydraulic system, causing various valves and fittings to catastrophically fail.
The Deparment’s investigation into the event revealed that the system’s pressure transducer was contaminated by water and faulty.
Similarly, the two mechanical system safety relief valves did not activate as they had been closed up from corrosion.
The Department has recommended that mines review their maintenance management systems to ensure safety-critical systems that control hydraulic pressure are running properly.