OT- personal safety for everyone

[just the cowboy]

Always thinking about it.

When working around machines I am always thinking safety, even now in the plant I work at any time I start a machine a always warn "clear" before pushing any button. Even though it is not required in this plant it is ingrained into me from years of warning people.
As far as PLC programing I don't think I'll ever get over the "What if" "Did I miss anything" part. Still I wonder if programs I wrote 20 years ago are fine, because I think of people first.
One of the things I would tell the guys that worked for me was "don't let a manager talk you into doing something unsafe to get production up". If they try to force you, write up a letter saying “I want you to do this ________ that is an unsafe act" Then bring it to me and we will go to the plant manager and get them fired. Funny thing is when you ask them to sign it they always come up with a safe way.

 

[Pete.S.]

On our newest lines, we've got the power to all of the machine's servos and VFDs partitioned from the control circuits. For routine stuff (cleaning inside the machine, minor servicing), the operators can lock that disconnect, lock out the air, and they're set. The 24V control circuits, PLC, HMI, etc. can stay powered. When they unlock, the only delay is waiting for drives to reboot, which is just a few seconds versus waiting a minute for the HMI to boot.

That is still somewhat old thinking and can be done even more efficient and still as safe or even safer.

OSHA doesn't require LOTO for routine stuff, if there are alternative measures to ensure operator safety.

That could for example be a safety PLC with all the proper sensors and actuators to make sure the area the operator is about to entering is safe.

It's not as easy as it sounds though from a design perspective as there is a lot to consider. If you are designing for the international market you have standards like ISO 13849-1 to follow to ensure compliance.

PS. Good discussion guys.

 

[bdjohns1]

OSHA doesn't require LOTO for routine stuff, if there are alternative measures to ensure operator safety.

That's actually only true if the routine stuff is during normal production operations.

1910.147(a)(2)(i)
This standard applies to the control of energy during servicing and/or maintenance of machines and equipment.
1910.147(a)(2)(ii)
Normal production operations are not covered by this standard (See Subpart O of this Part). Servicing and/or maintenance which takes place during normal production operations is covered by this standard only if:
1910.147(a)(2)(ii)(A)
An employee is required to remove or bypass a guard or other safety device; or
1910.147(a)(2)(ii)(B)
An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being processed (point of operation) or where an associated danger zone exists during a machine operating cycle.

Note: Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).​

And, moving further on:

1910.147(b)
Definitions applicable to this section.

Normal production operations. The utilization of a machine or equipment to perform its intended production function.

Servicing and/or maintenance. Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning or unjamming of machines or equipment and making adjustments or tool changes, where the employee may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy.
​

So, the only time you don't have to LOTO is if all of the following are true:

1. The machine is in a production mode. Not doing a changeover, not doing sanitation (and I work in a food plant, so there's lots of that type of activity). We've defined production internally as "from the time the first product enters the filler to the time the last product leaves the end of the line".
2. The task is routine and repetitive and integral to operation. Cleaning up drips from a nozzle is routine. Replacing a pneumatic cylinder rated for 20-30 million cycles isn't routine.
3. The task is a "minor servicing activity".
4. As you mentioned, you have alternative means of protection.

If you can't satisfy all of those conditions, LOTO it. Best practice I've seen to avoid getting into arguments around what the R/R/I tasks are is to have them documented and posted at the line. If someone wants to add something to the list, they need to prove to me (and my boss in corporate safety) that it meets those criteria.

When you've got a facility like mine, where your newest filling line is PLe and your oldest line's got a faceplate from the 1940s, and operators who flex between them, you don't plan on them knowing the differences in safety systems.