Part Two: Protecting the Confined

After reading last week’s blog, you’re probably in suspense about how to protect employees who are exposed to confined workspaces.  OSHA states that if you have a ladder for accessing the confined space, you need a mechanical means of worker extraction with a gear that has a 5 to 1 gear ratio.  Whenever you have someone who is working in a confined space, it is required by OSHA that an attendant is present above the space to monitor the worker in the confined area.

There are three types of Non-Entry Rescue Tripod devices:

1. Bi-directional winch attachment on the tripod system
2. 3-Way SRL that has a braking mechanism for fall arrest 
3. 3-Way SRL and a winch attachment (Winch should be man-rated)

Using a tripod that only has a winch attached is the most commonly used form of confined space rescue device because it is the least expensive option. Although this option is better than not having any form of mechanical ascent/descent, this solution is the most dangerous because it requires the attendant to be extremely vigilant about the worker’s location and the amount of slack that is above the worker while they are either moving up or down in the vertical space. If there is extra slack on the line, the worker is more likely to experience injury if they suddenly fall and the attendant needs to use the winch as the worker’s sole means of rescue from the space.

A tripod that has a 3-Way SRL is the best medium-priced option that most safety managers should consider. The 3-Way SRL offers a braking fall arrest mechanism in the event that the worker experiences a fall while they are in the space. Since it is a self-retracting mechanism, this device is designed to maintain a safe amount of tension on the cable as it is either being released or retracted. This particular SRL also allows for upward and downward movement with a hand-controlled crank.

And the final tripod offers both a 3-way SRL and a winch. This system provides extra protection and support—sort of like wearing suspenders and a belt. This type of non-entry rescue device is required by OSHA when workers will need to be continuously raised and lowered into a confined space. The SRL has a fall arrest braking mechanism and bi-directional vertical movement options. Meanwhile, the winch will need to be man-rated in the capacity that meets your needs. By having both a 3-Way SRL and a winching mechanism attached to a non-entry rescue tripod, you are ensuring that any attendant can provide proper protection for the worker in the enclosed space.

PLEASE NOTE: Winches can come in formats that support personnel only, materials only, or both personnel and materials. Make sure that you have a winch that meets your needs. It’s very important that your winch and SRL have the right weight rating and enough vertical mobility to match the depth of the confined space that the worker needs to access. Most winches allow for a rescue time of 20’ per minute. However, it’s important to consider the element of fatigue as well.

For example, if a worker is 100 feet below ground, it will take approximately five minutes to winch that worker above ground. However, this process will probably take longer because the attendant will probably begin to get tired after a minute or two of winching his co-worker to safety. And if the worker is in the harness much longer than ten minutes, suspension trauma can become a threat. A good rule is that if someone needs to travel over 50 feet in order to do a job, it may be a good idea to have a different type of body harness or a bosun’s chair for the worker in the enclosed space. By using a harness that allows the worker to sit as they are being retrieved, the worker is less likely to experience suspension trauma (the sitting-style of harness relieves the pressure on the worker’s legs).

Another option is to use a power drive man-rated winch instead of a manual model. By having a motorized rescue winch, the person who is supervising the worker in the enclosed space will not need to worry about battling fatigue should the worker need to be lifted for long distances. All power drive winches must have a slip clutch in them for additional worker safety. The slip clutch will cause the winch to stall out and prevent a worker from being pulled in two different directions should they get stuck in the space.

Other things to consider:
You may need to have a special attachment (typically called a retrieval yoke) for the worker’s full body harness. This special harness accessory helps keep the winch and SRL attachments directly above the worker’s head. By keeping the attachment point directly overhead, the worker can be kept more vertical should they need to be retrieved from a confined space. Often times, a specialized style of full body harness designed for frequent raising and lowering of a worker will have two attachment points. One point will attach to the SRL for fall arrest should the primary winch fail. Then, on certain types of harnesses, a second attachment point will connect to shoulder d-rings or the top of a bosun’s chair. Please make sure that all of your equipment components are compatible with one another.

Most tripods will have several anchorage points built into their design. It’s important that the attendant who is above the confined space is also attached to one of the anchorage points on the tripod. If anyone is exposed to the fall hazard, they must utilize some form of fall protection, regardless of if you are in the confined space or monitoring someone who is in the space.

Alternatives to tripods are Davit arm systems. Davit arms are installed either permanently near a confined space access area, or they are attached to a portable base commonly referred to as a “Quad Pod”.  Davit arms are usually best installed on top of a piece of equipment that requires accessing confined spaces. Either way, the davit arm is another way that fall protection can be provided for people working in confined spaces. The davit arm system is designed to support a winch and/or SRL just like the tripod. However, the Davit arm is better suited for people who do not want their fall protection to cover the entire access area. Often times, large companies with a need to access multiple areas with confined spaces will use the davit arm system. Those companies prefer the davit arm because it can be easily transported to different locations either in the field on in their facility.

Protecting workers in confined spaces can be difficult because of the various restrictions that can apply. However, it’s important that the necessary precautions be taken into consideration to ensure the safety and protection of all workers at any given location. Always remember to check the compatibility of the equipment with the type of job and task that needs to be performed. Make sure that all of the equipment that you want to use is properly rated for the tasks that you would like to complete and the area where you or your employees need to work.