MSHA issues safety alert following tensioner bolt injury

The Mine Safety & Health Administration (MSHA) recently issued a safety alert following an injury caused by a tensioner bolt.

On July 17, a miner at a surface limestone operation sustained serious injuries while performing repairs on a belt drive motor.

During the repair process, the motor’s tensioning system was being adjusted when a 3/4-inch diameter all-thread tensioner bolt failed, causing the bolt to break loose and strike the miner in the face.

MSHA said spring-integrated designs with constant pressure and continuous vibrations pose potential safety concerns.

Best practices for mine equipment maintenance workers

MSHA listed best practices for preventing tensioner bolt-related injuries:

• Ensure all miners receive thorough training to identify hazards and perform tasks safely.
• Maintain all equipment and safety devices in proper working condition to ensure safe operation by reviewing manufacturer manuals prior to service, replacing worn or damaged components, and using tightening sequences to tighten as recommended.
• Check component quality by examining bolts, washers, springs, and nuts for visible defects like rust, cracks, corrosion, thread damage, or deformation.
• Conduct a risk assessment before starting work to identify and control all forms of stored energy, including mechanical, electrical, hydraulic, gravitational hazards, and unintended motion of equipment.
• Alignment matters: Ensure all components are properly aligned before bolt installation. Misalignment can lead to uneven stress distribution within the system, possibly leading to premature failure.