I need Help to find the right safety items in the code USA

[JeremyAdair87]

I am having a bit of trouble with mechanical engineers and safety.

They are doing things like saying "a light curtain is being used as a "go button"" while an operator sticks their hands in a live mill for part placement after incorrectly removing the safety door and "reducing its cycle time" by putting an automatic door with a 200 lb slide on it. Its pretty much a guillotine and is held out by a logic output.

We have two touch buttons that keep people's hands out of a small 85psi press. The two touches are again "a go button" so the operator can work in the rest of the cell, however the press is a major pinch point. The two touches were bypassed to "reduce cycle time" so the operator can work on other items in the cell which has 5 or 6 operations based around a mill.

We have safety devices going to PLC inputs. They want code that bypasses safety... Safety is done with electrically wired devices and not code.

First I need to study the codebook more but quickly I need help finding the osha, IEC, or NEC lines defining that it is not okay to do these things. I have used the NFPA 70E Risk assessment documentation, and clarified that injuries at the plant are the fault of the plant, and that we need to identify any hazard and determine probability of occurrence, injury, frequency of exposure, and likelihood of avoidance. "IT IS ON US to engineer IT", I say!

.... but the plant is says "it is not likely" we "can not increase cycle time" and "lets band aid this safety and make it slightly less risky and HOPE the operator doesn't stick their finger in that press again"... Murphy's law says they are going to stick their finger in it again and it is going to go to corporate that the machine "we made safe" is still hurting people.

It has been a long day. Thanks for listening.

 

[PLC Pie Guy]

Tell him to watch this!

https://m.youtube.com/watch?v=E5ydrE24_u0

if it doesn't work youtube - Industrial Accident in Malaysia


I showed this to my safety manager, she's panicking now trying to verify all the safety stops and the validity/placement of each. She is new to the job and needed to see the consequences of not having proper safety in place.

This pretty much sums it up.

 

[Pete.S.]

You often have to buy standards to find out exactly whats in it but if you search the net you might find some more info.

Here are some that could be interesting for you:

ANSI B 11.1 Machine Tools – Mechanical Power Presses – Safety Requirements for Construction, Care and Use

ANSI B 11.2 Machine Tools – Hydraulic power presses –
Safety Requirements for Construction, Care and Use

ANSI B 11.3 Power Press Brakes, Safety Requirements for the
Construction, Care and Use of

ANSI B 11.19 Machine Tools – Safeguarding when referenced by the other B 11 Machine Tool Safety Standards – Performance
Criteria for the Design, Construction, Care and Operation

ANSI B 11.20 Machine Tools – Manufacturing Systems/Cells –
Safety Requirements for Construction, Care and Use

ANSI/RIA R 15.06 Industrial Robots and Robot Systems –
Safety Requirements

UL 61496-1 Electro-sensitive protective equipment –
Part 1: General requirements and tests

UL 61496-2 Electro-sensitive protective equipment –
Part 2: Particular requirements for equipment using active optoelectronic protective devices (AOPDs)



PS. Another idea is to look at info from companies that sell safety devices like two button safety for presses.

 

[Pete.S.]

Hey, take a look at this for presses:

https://www.osha.gov/SLTC/etools/machineguarding/presses/twohandcont.html

and this for general info:

https://www.osha.gov/SLTC/etools/machineguarding/intro.html

 

[JeremyAdair87]

The Osha stuff is golden for my purposes. It says in plain English what to do and not to do. Now If I could just find the line that says you don't put nonsafety rated PLC I/O into a safety circuit I would be fine.

 

[jraef]

The Osha stuff is golden for my purposes. It says in plain English what to do and not to do. Now If I could just find the line that says you don't put nonsafety rated PLC I/O into a safety circuit I would be fine.

You won't find that, at least not yet, in the US and likely not for the next 4 years minimum. There had been a movement afoot to harmonize our safety standards to the rest of the world, but that is not likely to move forward now for a while.

However, that does NOT stop lawyers! How it would work is that IF someone gets injured, and they hire a good (relative term) lawyer that understands worker safety standards, they will jump all over the fact that a widely accepted and implemented safer method was in existence, but the owner chose not to implement it. That alone should drive companies to use the international standards whenever possible, and does for many large companies, but until some big high profile settlement makes the news on that, it's not likely to be heeded by the likes of what you are describing. I've seen 3 similar cases in the last 10 years (companies ignoring international safety standards and using loose interpretations of minimum OSHA standards), all three were settled out of court for big money, but with restrictions on publicity about it.

 

[JeremyAdair87]

This is from the osha website.
Safeguards must meet these minimum general requirements:
 Prevent contact: The safeguard must prevent hands, arms, and any other part of a worker's body from making contact with dangerous moving parts. A good safeguarding system eliminates the possibility of of the operator or another worker placing parts of their bodies near hazardous moving parts.
 Secure: Workers should not be able to easily remove or tamper with the safeguard, because a safeguard that can easily be made ineffective is no safeguard at all. Guards and safety devices should be made of durable material that will withstand the conditions of normal use. They must firmly be secured to the machine.
 Protect from falling objects: The safeguard should ensure that no objects can fall into moving parts. A small tool which is dropped into a cycling machine could easily become a projectile that could strike and injure someone.
 Create no new hazards: A safeguard defeats its own purpose if it creates a hazard of its own such as a shear point, a jagged edge, or an unfinished surface which can cause a laceration. The edges of guards. for instance, should be rolled or bolted in such a way that they eliminate sharp edges.
 Create no interference: Any safeguard which impedes a worker from performing the job quickly and comfortably might soon be overridden or disregarded. Proper safeguarding can actually enhance efficiency as it can relieve the worker's apprehensions about injury.


My M.E.s consistently create new hazards, fail to prevent contact with moving parts, and fail to make secure fixes that can not be bypassed. I could care less about a law suit.

I don't want my operators loosing a finger or their life and I am fighting half cooked garbage ideas to make the bean counters happy with a $500 fix that I say is not good enough while they say "well you don't have proof. That is you opinion. It has gone 20 years and has not happened." (bull#&$^ it wasn't recorded)

The above are the MINIMUM requirements. Forcing them to follow those guidelines alone with the risk of an osha violation serves my purpose now.

I still need to hit the books hard with a yellow sharpy. These lawyered books are hard to read though... and harder when you get a manager that doesn't understand what a conductor is making safety decisions.

 

[JeremyAdair87]

You won't find that, at least not yet, in the US and likely not for the next 4 years minimum. There had been a movement afoot to harmonize our safety standards to the rest of the world, but that is not likely to move forward now for a while.

Back when I did it more, There was a section for Cat 1 through Category 4 safety enclosures. They have now been replaced with SIL ratings and I am unfamiliar.

Inside the Cat rating it did state that you had to have all safety rated devices. If a device was not safety rated then your category rating was ZERO. PLC outputs are a 1 dollar relay from china. They are not safety rated.
I just don't remember where to find it. It was from a master electrician I trusted from a company that did safety in my area.

 

[Gomez_]

NFPA 79 - Electrical Standard for Industrial Machinery
9.4.3.4.1
Software- and firmware-based controllers to be used in safety related functions shall be listed for such use.

In other words its has to be a safety rated PLC.

This is what we follow as an OEM.

- Gomez

 

[James Mcquade]

THIS IS REQUIRED ! get with safety, engineering, management, maintenance, and the operators and do a risk assessment. that will tell you what must be done ! end of discussion.

as already pointed out, look at nfpa 79.
Two hand anti tie down systems cannot be bypassed.
machinery cannot operate with safety guards removed / bypassed.

if they over rule the safety assessment and force you to make the changes, get it in writing with everyone's signature ( bet they don't sign it).
take the copy home and put it in a safety box.

Me personally, I would refuse to do it.
if an accident occurs, osha comes in, does their investigation, and you get blamed. the engineers will deny ever saying anything about bypassing safeties. You get fired, criminal charges may be pending due to what happened, the company gets fined, and those responsible get away with it.

I made a change to a machine back in the 90's and took out a test, big mistake! The one thing I had was a piece of paper that authorized me to make the changes and the engineer's signature. Someone changed a part design without authorization and that test would have failed the part (100%).
I cannot say any more (lawsuit still ongoing, but we were cleared from all wrong doing).

just my 2 cents.
james

 

[JeremyAdair87]

I have been refusing to do it. This was done by an M.E. PLC programmer and I have been here 8 months. I have refused many times to put controls into safety circuits. I've spent a 26 hour day rewiring a machine that hurt someone and took the Light curtain to an actual safety relay... they use motor starters as MCRs here.... I've been slowly changing over machines to real safety relays etc... I am fighting hard to do the right thing. I just have to back up what I am doing because I am rocking the boat of miss trained engineers and back yard farm house "electricians".

At the end of the day I am falling on my own sword, and trying to find any way to improve for the people on the floor. I'd rather fall trying to help them then just leave and be replaced by someone who will be a "yes man".

 

[hd_coop]

Hope this helps too. This is from ISO13849-1, section 6.2.4.

 

[Pete.S.]

Hope this helps too. This is from ISO13849-1, section 6.2.4.

Yes, ISO 13849 is the international standard related to safety components. It uses PL - performance level. Depending on the risk you need a certain performance level and to get that you need a certain level of safety in the components as well as how you connect and monitor them, the design so to speak.

It's replaces the older ISO 954-1 that uses categories.

The picture is misleading though as it only talks about the non-safety components.

 

[hd_coop]

Yes, ISO 13849 is the international standard related to safety components. It uses PL - performance level. Depending on the risk you need a certain performance level and to get that you need a certain level of safety in the components as well as how you connect and monitor them, the design so to speak.

It's replaces the older ISO 954-1 that uses categories.

The picture is misleading though as it only talks about the non-safety components.

ISO13849 still uses Categories. Categories are an important component of determining your Performance Level.

I'm not sure what you mean about the picture only talking about the non-safety components either...It is describing that Category 1 circuits must use "well tried" components. It goes on to expressly exclude non-safety rated PLCs from being considered "well tried" in Note 1.

 

[Pete.S.]

ISO13849 still uses Categories. Categories are an important component of determining your Performance Level.

I'm not sure what you mean about the picture only talking about the non-safety components either...It is describing that Category 1 circuits must use "well tried" components. It goes on to expressly exclude non-safety rated PLCs from being considered "well tried" in Note 1.

Well, ISO 13849-1 uses categories to talk about the design of the safety circuit but it's the PL that is the result and categories don't map to PL in a simple way.

Regarding "well-tried components" that is primarily used when you have non-safety components. Because safety components already have a PL rating. Category 1 is non-fault tolerant safety.

The way I meant is was misleading is that it talks about a very low level of safety that is not applicable to something like a press. You end up with PLe on a lot of stuff and PLd for most of the rest. Presses are also Annex IV machines under the Machinery Directive so they have special rules on the European market.

Normally for anything where the operator is picking something out of a machine, where you will get more than a bruise if you stick your hand in while it's running, you end up needing PLe. PLe means (for those not familiar with it) in simplified terms that you must use safety components with two channels with enhanced diagnostics so you can detect if one channel is not operating as it should.

If something like a light curtain is used you have to think about the time it takes to stop something as well as the distance between the light curtain and the risk zone.

There is more to it, so consider what I wrote above as just a starting point.