Equipment size and capacity in longwall operations over the last few years has increased significantly. As a result, electrical and hydraulic power requirements to operate longwall systems has increased, leading to greater danger.
According to the MSHA there have been 18 accidents involving hydraulic hoses in longwall incidents between 1995 and 2000 in the US. In one accident a longwall shearer operator was killed when he was struck with a 1-1/4 inch 4,500 psi main hydraulic line with approximately 15 pounds of couplings attached.
Hydraulic hoses, fittings, filters, and couplers should be sized and rated for your longwall systems capacity. Proper equipment selection, sizing, routing, clamping and mounting will greatly reduce the potential for future high pressure hydraulic system accidents.
To help prevent accidents, MSHA have released a number of best practices mine workers can follow to minimise the danger to themselves and others when working with hydraulic systems.
“Before retro-fitting or modifying high pressure hydraulic lines, it is important to use properly rated and sized couplers, filters, fittings, and hoses designed to handle your longwall systems specifications,” MSHA safety bulletin said.
“Mismatched components result in using additional fittings which can increase pressure losses and increase the chance of line failure compromising safety and performance.
“Monitor the high pressure pump gauge and the amount of emulsion used on your longwall. Hoses may have to be changed if the high pressure pump gauge is fluctuating more than normal or more emulsion is being used than normal.”
MSHA warned if any modifications have been completed, it was critical to mount and secure hoses in a fashion that minimizes the connection point(s) exposure to bending and shearing stresses.
It outlined that all high pressure hydraulic hoses should be mounted keeping in mind that hardware, guards, shields, and hangers must be utilized to maximize safety and performance. Special note should be taken that each side of the connection point is properly secured and that enough slack should be left in the hoses for pan and shield advancement to alleviate stresses placed on connection points.