Injury due to sudden fracture of spanner

Mine type

All mine types

Incident

At a small mining operation a plant fitter was injured when he fell backwards while tightening a bolt using the ring-end of a combination spanner. The spanner fractured without warning severing completely at the ring end.

Equipment

1½" (38mm) chrome vanadium combination spanner

Hazard

Using tools of substandard quality

Cause

Metallurgical failure analysis by materials engineering consultants ETRS revealed that the spanner failed by brittle fracture. Their report attributes the fracture to substandard heat treatment process during manufacture causing significantly varying hardness between the edge of the spanner to the centre (687 down to 309 on the Vickers scale)—the hardness results also suggesting that the spanner had not been tempered sufficiently to improve toughness within the harder regions.

Comments

There were no indications of misuse. The manufacturer of the spanner could not be traced. The only marking on the spanner was '1½ - drop forged - China'. It was cheaply manufactured.

Recommendations

• Purchase quality tools made by a reputed manufacturer. Low price tools may not necessarily save you money and may cause injury.
• Select correct type and size of tool for the job.
• Do not add or use too much leverage—this will ruin a tool and cause injury.
• Avoid sudden slips and injury by keeping the body in a balanced position.
• Establish regular tool inspection / audit programs and check tools before use.
• Store tools properly to avoid damage.

Authorised by Peter Minahan - Chief Inspector of Mines

Contact: minesafetyandhealth@dnrm.qld.gov.au

Issued by Queensland Department of Natural Resources and Mines