What is a Confined Space?

What is a Confined Space?

What is a Confined Space?

By Daniel Fleck

So you’re staring into a space… It looks a bit tight in there. But is it a confined space? According to OSHA there are three criteria that make up a confined space and all three must apply:

  • Can you fit in there? (large enough for workers to enter and perform certain jobs)
  • Are there limited ways out? (limited or restricted means for entry or exit)
  • Is it designed for people to always work in? (not designed for continuous occupancy)

Some of these criteria seem easy to determine. A bathroom is not a confined space because it’s designed for occupancy. A 55 gallon drum is not a confined space because it’s not big enough to enter and work. A warehouse is not a confined space because there are generally many exits. But this can actually be a tricky question for a lot of cases.

For one example, is the top of a fixed cone roof tank a confined space? You can work on top of it, you can only leave via the tank stairs, and it isn’t designed for continuous occupation. Are stairs considered a restricted means for entry?

If having a single stair entry point triggers a confined space, then some secondary containment areas might also be confined spaces.

How about the top of an external floating roof (EFR)?

The only difference in most cases is an extra set of self-leveling stairs to egress. What if the EFR is near the top of the tank where a worker can see over the top of the tank shell? Does that matter?

What about if you have a domed EFR with the rolling stair retained and an open hatch? The criteria are essentially the same. Are all of these confined spaces?

Determining what is a confined space and what is not is generally left to a facility owner to decide. Some owners have determined vessel skirts that aren’t big enough for an entire body entry are confined spaces. Some might even consider excavations confined spaces. The policy of what is and what is not a confined space should be in a clear written confined space standard and have a logical demarcation with defined boundaries.

How does an employee or contract worker know if a space is considered confined? Obviously being aware of the confined space policy is critical and all employees exposed to confined spaces should be trained on that policy. Do you need to post a sign? OSHA only requires warning signage and restricted entry for permit-required confined spaces.

So what makes a confined space permit-required? There are 4 criteria, with any one of these triggering a permit requirement:

  • Does it contain or have the potential to contain a hazardous atmosphere?
  • Could a worker be engulfed or drown? (Contains a material that has the potential for engulfing an entrant)
  • Could a worker be trapped or asphyxiated (Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section)
  • Does it contain any other recognized serious safety or health hazard?

The second and third criteria are pretty straight forward. Basically, any steeply sloped floor or any space still holding reasonable depth of liquid or granular material would be a permit-required confined space.

The first criteria is pretty vague. What does potential mean? Are all confined spaces in a classified area permit-required? Or at what likelihood of hazardous atmosphere do you need to consider permit-required? This is why there is a difference in the example above for a fixed roof vs a floating roof. There should be a threshold at which the potential for a hazardous atmosphere can bump a confined space from non-permit to a permit-required space. The top of a floating roof clearly has more potential for a hazardous atmosphere than the fixed roof on top of a tank. The lower the floating roof is, the higher the potential for a hazardous atmosphere. A covered floating roof has a higher potential still. Again, a facility owner needs to determine what level of potential should be the threshold for a permit-required confined space.

The last criteria is the most vague. It is very open to interpretation. Could the top of a fixed roof on an extremely hot or cold day be a permit-required space because it has a thermal stress hazard? Could the top of a fixed roof that doesn’t have handrail all around be a permit-required space because there is a fall hazard? What if it is wet or icy and there is a slip hazard?

All confined spaces are not the same and all permit-required spaces do not have the same hazards. Thankfully, the OSHA rules do give guidance on how to treat differing levels of risk in confined spaces. Confined space requirements are outlined in 29 CFR 1910.146 for General Industry and 29 CFR 1926 Subpart AA for Construction environments (Agriculture and maritime have their own sets of rules). Stay tuned for the next blog post in the series where we will dive deeper into permit-required confined space classifications and their safety requirements.



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