So I posed the question to over 30,000 safety pros across my LinkedIn and Facebook groups and SAFTENG members, and as I suspected, there was a lively debate on this matter. I have received numerous requests to break down the evaluation like I have done for other “tricky” spaces that fall outside the traditional CS/PRCS type of spaces. So buckle up as this may be a wild ride for some of you.
First, for those who are not SAFTENG members, I will state up front that the large CNC machines, as shown below, are by definition a PRCS. Where I take a wild turn is that I do NOT think OSHA would use 1910.146 to issue citations and instead simply issue LOTO violations, as they have done many times before.
Is this CNC machine a Confined Space (CS)?
The CNC machine has the following characteristics:
1. Is large enough and so configured that an employee can bodily enter and perform assigned work
This size CNC machine can hold several adults at a time and all could perform assigned work, such as cleaning it.
2. Has limited or restricted means for entry or exit; and
The size of the opening is NOT the restriction. It’s the height that causes the limited means of entry or exit. The facility uses a four-rung platform ladder to access the opening and then steps inside the machine. OSHA has repeatedly stated that the use of a ladder is a “limited means of entry or exit”. There is a chance that we could use some mobile stairs, as long as those stairs meet 1910.25, then we would NOT have “limited or restricted means for entry or exit”. And if we removed this characteristic, we would NOT have a CS, and if we don’t have a CS, then we would not have a PRCS.
Under what circumstances will stairs or ladders constitute a limited or restricted means of egress under the standard?
Ladders, and temporary, movable, spiral, or articulated stairs will usually be considered a limited or restricted means of egress. Fixed industrial stairs that meet OSHA standards will be considered a limited or restricted means of egress when the conditions or physical characteristics of the space, in light of the hazards present in it, would interfere with the entrant's ability to exit or be rescued in a hazardous situation.
Source: https://www.osha.gov/sites/default/files/enforcement/directives/CPL_02-00-100.pdf
3. Is not designed for continuous employee occupancy.
These machines are not built for employees to occupy continuously. They are manufacturing machines. Although employees can enter them and do assigned work; which is how they get labeled as a Confined Space (CS).
Now we move to the stage where we evaluate this CS to determine if it rises to the level of being a Permit-Required Confined Space (PRCS). For a CS to rise to this level, it must have at least one (1) of the following hazards:
1. Contains or has a potential to contain a hazardous atmosphere
These machines use cutting fluids/oils and coolants in their operation. However, these fluids have LOW vapor pressures, high flash points, and high PEL/OEL/TLVs. This means a hazardous atmosphere would be tough even to consider. However, doing Hot Work inside these machines before they get a good cleaning could result in a serious fire!
2. Contains a material that has the potential for engulfing an entrant;
This is clearly no applicable to these types of machines.
3. 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
This is clearly not applicable to these types of machines.
4. Contains any other recognized serious safety or health hazard.
This item is vaguely worded and creates a lot of debate amongst those who perform CS evaluations. I like to say this item covers the “physical/mechanical” type of hazards, such as agitators, ribbon blenders, augers, etc. In the case of CNC machines, it is the movement of the machine parts that pose a serious hazard.
And this leads me to how these spaces can be easily reclassified using (c)(7) by locking out the energy sources that pose the entrant(s) to said hazard(s).
But when we make these machines a PRCS, we create a serious conflict in that 1910.146 states:
Entry means the action by which a person passes through an opening into a permit-required confined space. Entry includes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space.
This is where I venture off the standard and will just say, YES – a CNC machine like the one shown in the article is indeed a PRCS by the classical definition as stated by OSHA. However, I professionally believe that this standard does not apply to this type of machine. Workers break the plane of these machines hundreds of times a shift and are fully protected in this operation by the interlocks on the doors. These interlocks are in place to permit the safe human-machine interface of the worker putting in and removing pieces to be processed by the machine. We can not take credit for these interlocks in our CS/PRCS evaluation; I am mentioning them only to show their intent to allow the worker to “break the plane” of these machines, and OSHA never intended for this to be an “entry permit” task.