According to federal data, eight miners were killed in two separate incidents at US operations since 2003 as a result of cutting torch use underground.

“Methane tests are critical for safe cutting or welding in underground coal mines and are somewhat different from methane tests used for general mine ventilation, where tests are made at least 12 inches from the roof, face, ribs and floor,” the agency said.

“This distance requirement is not applicable to cutting or welding activities, when methane tests must be made in locations where methane is likely to exist.”

Methane tests, MSHA said, must be made at or near the surface of these areas, not 12 inches away. Also, testing must be performed within any fully- or partially-enclosed areas that could be exposed to ignition sources.

Cutting or welding is prohibited in areas where the atmosphere contains a 1% or higher concentration of methane.

For a longwall mining system MSHA said adequate testing, cleaning, and rock dusting generally required raising the chain conveyor and securing it above the mine floor prior to cutting or welding.

“In this way, the space beneath the conveyor line can be ventilated and tested for methane, accumulated combustibles can be removed, and the area can be thoroughly wet down and rock dusted,” it said.

“Where raising the conveyor line is not practicable, other measures may be necessary to minimize the danger of ignitions. MSHA recommends using a probe connected to a detector for methane examinations in hard to reach areas.”

As a precaution, mines also must make diligent searches for fire during and after cutting and welding activities, as longwall chain conveyor line components or covers on other equipment may obscure small fires.

MSHA has developed a program policy manual page for Section 75.1106 Welding, Cutting, or Soldering with Arc or Flame Underground at http://www.msha.gov/regs/complian/ppm/pmvol5k.htm#132.