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Incident Alerts


October 1, 2003
By Pulp & Paper Canada

There are always two key components that are required to prevent incidents and injuries: the proper skills to do the job and the awareness that hazards are present.If one of the components is missing,…

There are always two key components that are required to prevent incidents and injuries: the proper skills to do the job and the awareness that hazards are present.

If one of the components is missing, workers are at great risk of getting involved in a safety incident.

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To acquire knowledge, we need training. In training circles they say: “Our ability to learn is limited by the environment that we are exposed to.” So in the field of safety, it is crucial that incident reports be shared as widely as possible as a way to broaden everyone’s exposure to incidents that occurred, thus raising knowledge and awareness of potential hazards that may exist while performing a job.

Following are examples of injuries and incidents that happened because someone did not have the ability to recognize the source of the danger.

Tank ruptured during hydrostatic pressure test

A mechanical contractor was conducting a hydrostatic pressure test on newly installed storage tanks using water from a fire hydrant. As it filled, air escaped through a relief valve at the top of the tank. He checked to see if air was being forced from the pressure relief valve on top and had been standing at the bottom rung of the caged ladder attached to the tank moments before the explosion.

Preliminary investigation concluded that the relief valve didn’t allow the air to escape fast enough and the lid blew off after reaching 50PSI+, the rating of the vessel.

It is critical to check the parameters when conducting non-routine work. In that case, both the volume of the water and the fire loop pressure were higher than the vessel design pressure.

Fortunately no injuries were sustained, but this incident had a great potential for serious injury, even fatality.

Cut-off wheel fractured during use: Worker killed

An air-powered angle grinder was being used to cut grooves into cast iron with a cut-off wheel. The wheel fractured during use and a large fragment of the wheel went through the worker’s face shield and into his face. He died as a result of the injury.

Manufacturer’s specifications state that the angle grinder is designed to operate at a pressure of 85 psi. It has a built-in governor that limits the maximum speed to 7,600 rpm. In testing performed after the incident, the grinder and the air compressor to which the grinder was connected appeared to be functioning properly.

At the time of the incident, the cut-off wheel was secured to the grinder’s drive spindle with a depressed centre backing flange designed to fit grinding wheels having depressed centres.

The following factors contributed to the incident:

To allow the grinder to be used in tight and awkward locations, its guard had been removed and had not been replaced. The side handle was removed, limiting the worker’s ability to safely hold and position the grinder.

The cut-off wheel was not designed for this type of hand-held cutting operation. It was rigid and flat, not suited or a depressed centre backing flange. It was also larger in diameter than what the grinder was designed for.

The wheel’s maximum safe operating speed of 4,500 rpm was less than the 7,600 rpm operating speed of the grinder. It may have been subjected to sideways forces during use and the curved backing flange may have forced the flat wheel into a curve.

The worker was using inadequate personal protective equipment considering that the grinder guard was not being used.

The way that the grinding wheels were being stored may have damaged them due to mishandling.

The angle grinder’s maximum rpm rating was not clearly visible on the grinder.

Recommendations:

Use manufacturer supplied grinder guards at all times.

Select the correct grinding wheel based on the operating speed and type of the grinder, type of the work and manufacturer’s recommended practices.

Use personal protective equipment that is appropriate for the hazard to which the workers are exposed.

All workers using grinders should receive general grinder safety training and job-specific instruction.

Operate tools within the manufacturer’s stated range of operating pressures.

Abrasive stones, discs and wheels should always include complete product information.

Herb G. Tessier is a senior consultant with DuPont Safety Resources with over 27 years experience in supervisory, technical and management with DuPont Canada.

Pulp & Paper Canada is pleased to publish articles on safety from industry experts such as John E. Little, Herb Tessier and Martin Lesperance, as well as encouraging submissions from contributors. Please e-mail anyao@pulpandpapercanada.com


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