State officials now describe the incident, involving an A.L. Lee Corp. shelter, as a "catastrophic failure" that pressured the interior of the steel structure.
"The initial determination is that the pressure build-up inside the container forced open both the tent deployment door and the air-lock access door, ejecting a supply container and three five-gallon water containers from the access door area onto a nearby [mine wall]," according to a U.S. Mine Safety and Health Administration report on the event.
In Friday's order, state officials said that "subsequent analysis of the failed shelter led to the discovery of cracks on multiple valves and fittings and identification of fittings that did not meet" recommended specifications.
A.L. Lee reported in February that it found similar problems with two other units that had been returned to its shop, according to MSHA records. State inspectors apparently found similar problems on shelters made by other manufacturers, records show.
"The demonstrated unpredictable service life of the brass valves and fittings is troublesome," the state said in Friday's order. "The current situation left unchecked represents a safety hazard."
MSHA officials had recommended examination and possible replacement of problem valves and fittings as early as January, but Friday's state order appears to be the first time regulators have mandated any action.
Amy Louviere, a spokeswoman for MSHA, said her agency has been working closely with the state and "will be issuing follow-up actions shortly."
The state's Friday order refers to a previous order, dated Sept. 29, but that order has not yet been made public.
Some inspections and retrofits of shelters already might have occurred, but it's not clear how many. Friday's order requires records of those inspections - being conducted by manufacturers -- to be submitted to the state.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.