Explosion Pressure Design Criteria for New Seals in U.S. Coal Mines

Seals are used in underground coal mines throughout the United States to isolate abandoned mining areas from the active workings. Prior to the Sago Mine disaster in 2006, mining regulations required seals to withstand a 140-kPa (20-psig) explosion pressure (30 CFR4 75.335(a)(2)). However, Program Information Bulletin No. P06-16 issued by MSHA on July 19, 2006 [McKinney 2006], requires seals to withstand a 345-kPa (50-psig) explosion pressure. The recently enacted MINER Act requires MSHA to increase this design standard by the end of 2007. This report provides a sound scientific and engineering justification to recommend a three-tiered explosion pressure design criterion for new seals in coal mines in response to the MINER Act. The recommendations contained herein apply to new seal design and construction in U.S. coal mines.