Published in June 2009 Australian Longwall Magazine

 

Newstan was the winner earlier this year of the NSW Minerals Council Health and Safety Innovation Award for its purpose-built Centennial Hydraulic Control System (CHICS). The system limits worker exposure to the failure of high-pressure fluid system components.

 

The Newstan team was driven to design the system after an incident at the mine when there was unintentional repressurisation of a hydraulic system after it had been isolated and dissipated. Employees were exposed to the potential for a high-pressure injection injury.

 

This was all in spite of the hydraulic system being isolated correctly, in accordance with Newstan’s Isolation Procedures.

 

The incident led to an investigation by the mine and the Department of Primary Industries which found the root cause of the incident was the failure of the seals in a 40mm ball valve.

 

The seals were found to be eroded by the hydraulic fluid flowing across the seals at high velocities. This occurs when the valve is partially open, or “throttled” – a procedure typically used when restoring pressure to the circuit to avoid “shock loading” to components.

 

It was decided that the best way to tackle the risk was through engineering controls.

 

With this in mind, the Newstan team – together with information and help from APT Training, a mine safety officer and the occupational health and safety committee – designed a new system which allows the isolation and restoration of pressure with a sequenced key system; pressure to be re-applied to the system at a controlled rate; dissipation of pressure at the isolation points; and visual verification of the isolation procedure all at one point.

 

This system can be installed as stand-alone unit or in multiples to establish a common board for complete area isolation of incoming supply. The system uses a bypass metering system to slowly introduce pressure to the hydraulic circuit during restoration.

 

This will reduce high-pressure transient spikes that fatigue hoses and components; prevent operators from metering flow with the ball valve during restoration, an operation which resulted in high-velocity fluid-eroding valve seals; and increase the reliability of the valve system and reduce maintenance costs.

 

The system also combines all isolation valves and components required, reducing the complexity and likelihood of physical damage.

 

“This innovation is an important and timely innovation for control of high-pressure hydraulic systems and represents a very significant safety improvement,” Centennial Northern Operations general manager Steve Bracken said.

 

“The transferability of this innovation to other longwall mining operations and industries which use hydraulic power will provide significant safety benefits.”

 

Centennial Coal holds the intellectual right to the design. A complete valve with Fortress Locks costs about $30,000.