While an optimal fire-protection system is key to any mining operation, the inspection and maintenance of its various parts is of equal importance, says industrial solutions provider Mechanical Rotating Solutions (MRS).

The South African mining industry has to report fires caused by, amongst others, equipment malfunction yearly.

MRS MD Franscois Steenkamp says equipment malfunction can be caused by electrical faults, spontaneous combustion, frictional ignition and lightning, amongst others.

He highlights that, while misaligned or damaged conveyor belts are often the source of frictional heating that leads to fires, some fires, especially in coal mines, may be difficult to detect.

“Often, mined areas in a coal mine form a zone of broken rock rubble, and the spontaneous heating of coal in these areas is not easily detected. MRS has, for more than a decade, serviced the coal mining industry with solutions addressing the threat fires pose to the coal mining industry.”

One such solution offered by the company is the supply and refurbishment of pressure-control valves and pressure-control deluge valves. Steenkamp advances that these are “a critical component of any mine fire protection system”, as the cost of replacing damaged valves is “extremely high”.

In addressing the high cost of such replacements, the company offers cost-effective solutions such as the efficient refurbishment and repair of these valves.

MRS refurbished a 10-inch Bermad FP 720-UL pressure-reducing valve, which showed signs of cavitation around the valve seat. This caused valve failure and a subsequent threat to the fire protection systems’ integrity.

“Cavitation damage is a form of hyper-erosion that can destroy control valves and piping, which, in turn, can result in unacceptable process failures and the lifespan of the valve and fire protection system being significantly shortened,” Steenkamp explains.

Further, having gained extensive experience in servicing collieries in Mpumalanga, MRS has frequently used Belzona 1321 – a Ceramic S-Metal – which comprises a two-component high-strength coating for the protection and refurbishment of metal surfaces subject to the severe erosion-corrosion at coal mines.

MRS’s refurbishing procedure for these valves entailed combining Belzona 1321 and the Belzona 1111 super metal epoxy.

The Belzona 1111 is a cold-curing 100% solids epoxy composite that is reinforced with silicon steel alloy. The composite can be used for several applications including bonding, protective coating, shimming, forming, rebuilding, wrapping, patching, sealing and filling.

Typical applications of the Belzona 1111 include impellers, water box ends and flange faces.

“We found the combination of Belzona 1321 and Belzona 1111 – to rebuild the damaged areas – to be the most suitable in refurbishing the areas most affected by cavitation on the Bermad FP 720-UL pressure-reducing valve. Belzona 1111 is well known for its high resistance to heat and wear.

“This combination is aimed at ensuring a reduction in high, unstable upstream pressure to maintain precise, stable downstream pressure, regardless of changing upstream pressure or flow, and requires only existing line pressure to operate,” he enthuses. 

Steenkamp emphasises that a fully refurbished pressure-reducing valve needs to meet the high demands associated with a new product while saving on replacement costs.