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Fall arrest in confined spaces


I was talking to a fall-protection user on the jobsite the other day and was pleased to see that he had made the right choices about safety gear. He had all the right equipment, was working with a partner and had a simple rescue plan in place. The right choices had been made.

Recent regulatory changes got me wondering whether the right choices were as easy to make for workers entering confined spaces where a fall hazard is present.

In general, a space that is not designed for continuous human occupancy in which a hazardous atmospheric condition may occur is deemed a confined space. While this is a simplified definition, it covers the main idea for this discussion. It includes elevator rooms, chlorine rooms and mechanical rooms, which fall under the building code. Yet, there are many sites where confined space is a factor that we often overlook. These include:

• rail cars, storage tanks, vessels and boilers, silos, baghouses and other spaces with only one point of entry that is hatch-like
• piping, sewers and ducts
• cargo tanks, double bottom tanks, cofferdams and oil tanks
• chutes, ore bins, crusher jaws
• ovens, furnaces and chimneys
• open-topped spaces more than 1.2 m. deep, like wells, open caissons and pits.

These locations can be defined as confined spaces when human occupancy is required for maintenance or repair. Consider some of the following points when selecting your confined-space gear where a fall hazard is present.

Starting at the harness, consider worker profile. (User profile can be described as the position in which the body rests during raising or lowering.) If a worker is required to enter a confined space with the assistance of a winch (or other hoist apparatus), harness selection should take into account the profile. Where the access point is very narrow and restrictive, it would benefit the user to be raised or lowered to minimize his profile, to prevent him from snagging on any part of the structure when immobilized. Shoulder D-rings help to reduce profile and should be used with the hoisting apparatus. Because the D-rings are at shoulder height, adequate head room is required to recover an immobilized worker. Back and sternal D-rings can be used where profile is less of an issue.

Anchor points always create issues when dealing with some of the situations mentioned above. After all, you can’t tie-off to the sky when you are working outdoors!

Various devices are available as viable solutions. Most recognizable is the tripod. It fits over top of the opening and allows one worker to descend at a time.

Davits are the next in popularity. Much like the tripod, davits fit over the opening to provide an anchor point for one worker. Both are built in different configurations to accommodate tight height and space requirements.

Recently, a variety of devices have hit the market to fill gaps where neither tripods or davits apply. They include devices that mount on the sides of tanks, provide stairs with anchorage to the tops of tanker trucks and rail cars, postmounted devices for transformers and a variety of horizontal entry systems for vessels and pipes, to name but a few. 

Connecting devices  are the final consideration. Workers can select everything from a basic, energy-absorbing lanyard to a powered winch.

Each jobsite will have its own, inherent characteristics and equipment needs. Be prepared, and talk to your manufacturer representative or a qualified person to help select your gear, write procedures and set up a rescue plan.

By John Fuke, 2006

Published with permission of On-Site Magazine

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