In a Program Policy Letter issued late last week, US Mine Safety and Health Administration coal mine safety and health administrator Kevin Stricklin reminded operators that federal Section 75.1725(a) indicates “mobile and stationary machinery and equipment shall be maintained in safe operating condition and machinery or equipment in unsafe condition shall be removed from service immediately”

The policy was designed to prevent the ignitions stemming from damaged, worn or missing cutting bits, and also to prevent accidents and injuries that can result from such situations.

“Using cutting bits with a carbide tip on continuous mining machines, roof bolting drill steels and longwall shearers and replacing damaged or missing bits reduces sparks associated with the cutting bits striking sandstone or other types of rock during mining,” he said.

“Failure to replace damaged or missing cutting bits and the lugs used to hold the cutting bits in place can result in sparks which are the most common source of methane ignitions. Operating continuous mining machines or longwall shearers with damaged or missing cutting bits or lugs will be considered unsafe.”

According to MSHA data, there were about 379 reported incidents of ignitions of methane while mining coal or rock with continuous mining machines and longwall cutting shearers between January 2002 and through March 2012.

One of the most high-profile of those events, according to many accounts, was the Upper Big Branch mine explosion in April 2010 that took 29 miners’ lives.

MSHA has made a printable, distributable version of the PPL available on its web site under the section “MSHA's Major Laws, Regulations and Policies”