MINE SAFETY AND HEALTH ADMINISTRATION
NORTH CENTRAL DISTRICT
Metal and Nonmetal Mine Safety and Health
Accident Investigation Report
Surface Nonmetal Mine
Fatal Machinery Accident
Waller Brothers Stone Company, Incorporated
Waller Brothers Stone Company Mine
McDermott, Scioto County, Ohio
I.D. No. 33-00176
April 7, 1999
Paul A. Blome
Supervisory Mine Safety and Health Inspector
Stephen W. Field
Mine Safety and Health Inspector
Eugene D. Hennen
U.S. Department of Labor
Mine Safety and Health Administration
515 W. First Street, #333
Duluth, MN 55802-1302
Felix A. Quintana
Paul E. Crabtree, drill operator, age 60, was fatally injured at about 7:05 a.m. on April 7, 1999, when he was struck by a compressed air line. Crabtree had 30 years, eight months mining experience, all as a driller at this operation. He had not received training in accordance with 30 CFR, Part 48.
MSHA was notified at 9:25 a.m. on the day of the accident by a telephone call from the OSHA office in Cincinnati, Ohio. An investigation was started the same day.
The Waller Brothers Stone Company mine, a dimension stone operation, owned and operated by Waller Brothers Stone Company, Inc., was located at McDermott, Scioto County, Ohio. The principal operating officials were Frank L. Waller, president; Connie D. Scott, senior vice president; and Lowell M. Shope, executive vice president. The mine was normally operated one, 8-hour shift a day, five days a week. A total of 53 persons was employed.
Sandstone blocks were extracted using wire saws in combination with hand held pneumatic drills. Individual blocks were split by the plug and feather method. The stone blocks were then transported by truck to the mill where they were sized. The finished product was sold for use as building stone or polished for use as chemical-resistant counter tops.
The last regular inspection of this operation was completed on June 18, 1998. Another inspection was conducted in conjunction with this investigation.
The accident occurred in the quarry. The equipment involved was WBQ 4011 Gardner Denver air compressor manufactured in 1956. The compressor displaced 284 cubic feet of air per minute at 100 to 125 PSIG and was driven by a 50-HP electric motor. A 250-gallon capacity air receiver tank was horizontally mounted adjacent to the compressor and both were rigidly attached to a steel I-beam framework which was supported by wooden cribbing. The piping was standard schedule 40 steel pipe with standard National Pipe Thread (NPT) threads. The compressor powered three hand held drills used to drill blocks in the quarry.
The compressor was connected to the receiver by a three-inch-diameter rigid metal pipe. The pipe entered the top side of the receiver through a three-inch tee and a short nipple. Connected to the outlet side of the tee was a 3-inch to 2-inch diameter reducer, followed in succession by a short nipple, a shut off valve, another short nipple, and a two-inch diameter tee. The top of the two-inch tee had piping that reduced down for a pressure gauge. The bottom of the two-inch tee had approximately 4 feet of vertical pipping that included a union and an elbow at the bottom. A 3-inch-long nipple was screwed horizontally into the elbow near ground level. The piping that went to the air drills was attached to this nipple via a union. This union, provided with a threaded nut having 12 threads per inch, was the point of separation which caused the pipe to rotate forcefully. The compressor had been taken out of winter storage and moved to the quarry two days before the accident. It had been used about two hours the first day at the quarry and was used all of the second day, but was stopped at noon to tighten the pipe unions, including the one that failed. The unions had vibrated loose and were leaking to the extent that a sufficient supply of air was not getting to the drills.
On the day of the accident, Paul Crabtree (victim) reported for work at 7:00 a.m., his normal starting time. He met Terry Blevins, foreman, Shane Muller, equipment operator, and Kris Anderson, driller, at the tool shed. A short time later, Anderson went to start a water pump and Crabtree started the air compressor. Blevins and Muller looked at something on the front-end loader.
Crabtree apparently followed the usual routine, which was to start the compressor, bleed any water from a valve on the bottom of the air receiver while the pressure was building up, and then close the drain valve. Crabtree stood next to the air receiver, watching the pressure gauge on top of the tank, until the pressure built to approximately 90 PSIG. A few minutes later the air line from the receiver tank separated at the union, causing the pipe to rotate, striking Crabtree on the head. Blevins, Muller, and Anderson all heard the noise when the pipe separated. Blevins went to the compressor and found Crabtree lying on the ground. He sent Muller to call the local 911 emergency assistance number while he and Anderson attended to Crabtree. Emergency medical personnel arrived a short time later and the victim was pronounced dead at the scene.
Test results concluded that althought the threads in the union were very worn, there was no evidence they had been cross threaded or pulled across each other. These tests also showed that the union would hold with the maximum pressure in the receiver until the thread engagement was one-half turn or less. These factors indicate that vibration from the compressor was transmitted to the union causing it to loosen and evenually separate. Lack of a flexible connection between the air receiver and the compressor to absorb the vibration was a major contributing factor.
Order No. 7823267 was issued on April 7, 1999, under the provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this operation on April 7, 1999, when a coupler failed on a compressed air line of the 50 h.p. compressor, causing the metal line to whip and strike the driller in the head. This order prohibits any work on or near the compressor. This order is issued to assure the safety of persons at this operation until the affected area can be returned to normal operation as determined by an authorized representative of the Secretary. The operator shall obtain approval from an authorized representative of the Secretary for all actions to recover and restore operations in the affected area.
Related Fatal Alert Bulletin:
Persons participating in the investigation:
Waller Brothers Stone Company, Inc.
Frank L. Waller, president
Connie D. Scott, senior vice president
Terry Blevins, foreman
Mark E. Ross, driller
Kris R. Anderson, driller
Shane P. Muller, fork truck operator
Scioto County Coroner's Office
Dr. Thomas Morris, coroner
Scioto County Sheriff's Office
Paul Blaine, detective
Ohio Department of Natural Resources, Division of Mines and Reclamation
James F. Myer, Ohio mine safety manager
Gary Rothwell, mine safety inspector
Mine Safety and Health Administration
Paul A. Blome, supervisory mine safety and health inspector - Marquette, MI
Stephen W. Field, mine safety and health inspector - Marquette, MI
Eugene D. Hennen, mechanical engineer P.E. - Technical Support
James D. Strickler, mine safety and health inspector - Newark, OH