Emergency Stop button not working 10

[Skogsgurra]

There's this saw mill where the safety is built around gates, light barriers and quite a few red mushroom style emergency buttons that are connected via several AS-interface buses, around ten of them.

We were asked to go and have a look at the mill. There were a multitude of reasons for that. One of the main reasons was that there were a lot of nuisance stops. We traced the stops to the AS-i buses and the interference level present on them (PWM drives in hundreds) with motor cables running parallel to the yellow bus cable. The yellow cable was in separate and well grounded trays, but the interference was still quite high. After connecting the GND terminal of the Masters to ground (an oversight from the panel builder and commissioner), the interference level was a lot lower and the bus worked a lot better.

Then, we noticed that there were Emergency Stops that didn't work at all. They had been crossed out in the PLC program, but left for anyone to see and press in the plant. Someone had given up and just left the saw mill with the Emergency Stops in non-working order. There wasn't even a sign or a note about the non-functioning devices.

After this long introduction, the question is short and simple: On a scale running from Stupid via Careless and Irresponsible to Criminal - where would you put such a behaviour?

The second question is also simple: What about OSHA and legislation? What about laws in EU? I have never seen anything like this before and welcome any view on the matter, be it emotional, factual or whatever.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[controlsdude]

MintJulep

I totally disagree with that: "Safety and Software do not and can not ever go together."

When that engineer is done with all the estop software I have seen, its all locked down, and if someone should go in there and change it usually the system will fault out, if they do not have the key.

So, any estop can be bypassed either hardwired or software, its up to that engineer to commission it correctly, leave it in a state where it operates to that SIL level, and train the people left behind, maintenance, on how to maintain it.

 

[Skogsgurra]

IRL, CD. IRL - that seems to be kind of an impossible dream.

Of course, hard-wired circuits are even easier to by-pass or override. But that is usually also easier to detect and restore.

The problem in this case is that there's no "safety culture" at all. OK, there is one - you will be reported if you are seen without hard hat and hi-vis vest. But that is all "safety culture" there is.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[davidbeach]

That's not a safety culture, that's safety theater.

 

[ScottyUK]

Ha-ha, that comment is noted for future use.

 

[Skogsgurra]

Agree. Absolutely!

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

I spent a short time working for a contractor some years ago where the field workers often repeated the phrase:
"Safety as a weapon!"

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

This is a perfect example. Because all it took to violate the SIL was for the on-site commissioning engineer or a plant engineer to hack some of the code out.

Really? All it takes to bypass a hard-wired E-stop is a screwdriver and a few seconds of time.

 

[Skogsgurra]

Not quite so - there's seldom a SIL level associated with a hard-wired emergency stop that can bypassed that easily.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

I had a talk with the head of safety for our company a few days ago. Corporate hubris, corporate compliance, (don't rock the boat), attack the messenger, denial. Felt like making water into a very strong wind.
Today we just had another "near miss" with a live cable that should have been de-energized.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

I finished the report about one week ago and mailed it to our customer (the company that built the line).

The report had a section on how to best handle safety, saying that the Safety Officer should initialize a thorough test of all interlocks and emergency stops, that there should be a detailed protocol that the Safety Officer should sign and that this protocol should be available to the workforce (be put on the company bill-board).

Thursday last week, I got a phone call from our customer. He thanked for work done and told me that the complete report (including lots of other problems with bus interference, motor insulation, bearings etcetera) had been sent to the mill and, it seems, is now available for all (operators, maintenance, bean counters, management) to read.

That is very satisfying and I think that "we take safety seriously" is a little more than just a saying in this company. They just needed the heads-up. The outcome surprises me, but I am glad it worked.



Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.