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Defeating Machinery Safety Measures - the worst you've seen?
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Posted By Heather Aston Following on from the control panel isolation thread, we've obviously got a lot of people on here who've been involved in machinery safety.
What's the worst example of defeating machinery safety systems you've ever come across. No names no pack drill obviously....
In the rubber industry we have 2-roll mills for mixing rubber - basically like a big horizontal mangle with metal rollers that rotate inwards towards each other forming a central nip. Clearly if this will squish rubber it will squish people.
Mills have a horizontal trip bar across the face of each roller, which protects the operator from being pulled into the nip by braking rolls before he can reach said nip.
Many years ago, in a factory far far away that shall not be named here, an operator was running some long strip onto a mill. Because the strip was heavy, it kept catching on the bar and tripping the mill out, which meant he had to keep going to the control panel and resetting it.
(You can just see this one coming can't you?)
Anyay the operator got fed up with this, went and found a nice piece of 2 by 2 and jammed it under the trip bar.......
The inevitable happened, he got the strip wrapped round his wrist and it pulled him in towards the nip. Naturally the bar did not trip. Alerted by his hysterical screaming, a second operator just managed to knock the piece of wood out and trip out the mill before the first operator went through the nip and ruined the batch of rubber (bits of squished flesh won't cure properly)
Brown trousers and very red faces all round.
Heather
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Posted By Hilary Charlton I heard one of a hopper for chopping metal swarf which was placed on a hillside in a barn type structure from which it was fed.
Obviously it was well guarded with rails etc to stop people from falling in. Unfortunately, one day a hapless sheep walked through the barn doors which had been accidentally left open - the rails which were at the ideal height to prevent people falling in meant that this poor unsuspecting sheep walked straight underneath.
Mutton anyone?
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Posted By Jason Gould We probably all know that most maintenance personnel and smart assed operators carry a spare magnet, and the front end of an interlock in his pocket amongst other picking lock devices.
It is a very good topic you raise and should not be restricted to machinery. Consider other shortcuts that commonly take place.
Cleaning extrusion rollers with a cloth whilst in motion (result pellitised fingertips and skin peeled up to wrist.
And my favorite is when a qualified mechanical digger mate of mine was asked to dig a trench for a new extension. It was 10 feet deep and 5 feet wide (for underground cables etc). He left digger in trench (raining) whilst on lunch and banking gave way. We was all asked to try and dig out the treads in this trench :( yes I was there in trench digging with shovel etc looking at these sandy mixed mud walls).
Result in end was our boss hired a bigger digger to pull out smaller digger. He used unqualified smart-ass of the company to drive this time using the bigger digger. He later went sideways down trench but used his shovel to maneuver himself out with just a broken window.
Next day he hit underground cable but for whatever reason he cleared the cab with no damage. Result was nobody hurt this time and the workers involved had the p**s taken out of them, by the boss as well.
The sickening side of this story was that when the Electric board tried to bollock our gaffer he threw them off site. Nothing heard of since leaving remaining workforce with the impression that H&S was a bribed game. A classic sample of the bad boss, unthoughtfull qualifed, accepting risk taker and the remainder of the workforce now believing H&S inspectors are all bribed.
I am sure there are a thousand similar places and situations every day.
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Posted By Karen Todd I noticed a compactor working with an interlocked door lying open. Upon further examination, I discovered that the switch was broken, but that a wire had been used to bypass it back to the control panel.
I then discovered, when I asked a bit more about the workings of the compactor, that the bin release mechanism was difficult to access and was actually inside the interlocked cage underneath the bin lift mechanism, so what they did was put the bin lift bit up, propped it with a pole, and stood underneath it to undo the bin release mechanism (putting themselves at risk of being killed should the bin lift mechanism fall). This was rectified very simply by moving the bin release mechanism handle about a foot to the left, outside the interlocked cage...
Karen
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Posted By fats van den raad Company using old (ancient) bale press to squeeze excess caustic soda out of bales of cotton pulp after mercerising in caustic soda bath before sending said bale in to shredder to be shredded. The bale press was a particularly cumbersome machine. It basically consisted of a table, a sweeping arm, and then the jaws of the press itself. Bales of caustic soaked cotton pulp would be deposited on the table surface by chain conveyor, from where the hydraulic sweeping arm would sweep the bales into the jaws of the press, cotton gets a few tons of hugs, and then dropped in to the shredder. Hydraulic sweeping arm was always getting stuck with bits of cotton wedged underneath it. This resulted in the operator having to stop the process, gain access to the table, clear the blockage restart the whole process from the front to the back. This could take up to an hour. Because of the potential hazard of particularly the bale press, the guarding that was employed was a fence around the whole machine. 1 gate, several interlocks on it, big padlock, key only available from shift supervisor. They thought they had it sorted. Saturday afternoon shift, and the hydraulic sweeping arm sticks halfway across the table. Our friend the operator thinks, "sod this for a bowl of cornflakes" and CLIMBS THE FENCE, gets on top of the table and clears the blockage under the arm. Of course as soon as the blockage was cleared the arm continued on its way to sweep the bale into the jaws, taking the operator with it.
Another operator saw him get crushed in the jaws, and managed to stop the machine before he got dropped into the shredder. At least his family had a body (sort of) to bury.
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Posted By Zoe Barnett One which had me banging my head against the wall:
Once upon a time in the land of far beyond there was a road tunnel which went for about half a mile under the river. This was dual carriageway in either direction and had the attendant requirements for maintenance, traffic management, clearing of accidents and so on.
The King of Far Beyond had to keep his people happy by not spending too much of their taxes, so he only employed one engineer who could supervise this maintenance and all the other work.
The Court health and safety officer asked what happened if something urgent happened whilst this engineer was on holiday or at home. He was told that the engineer was on 24/7 call, 365 days a year. The King was very proud of the fact that he had thought of everything. Why, should the engineer have been at a party no expense would be spared. A taxi would be sent for him, so even if he was too drunk to drive he would still be able to get to the tunnel.
Anyone see the problem here?!
(Rumours that the safety officer was taken to the Tower have not been proved...)
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Posted By Karen Todd Another one:
A technician needed to make an adjustment to a machine while it was running. The machine had interlocked doors on it. The technicians also had a jog handle. However, he needed to use 2 hands to make the adjustment, so if he used the jog handle which meant he could make the adjustment with the doors open, he'd only have 1 free hand.
He opened the interlocked doors, climbed up onto the rotating bed of the machine, got an operator to close the doors, start the machine, and he made the adjustment whilst inside the interlocked doors of the machine while the machine was running.
A further one that I have seen that apparently is quite common, is where the light curtain on a cutting & drilling line for steel beams has a gap at the end (why bother to have a light curtain, eh?), so someone can go around it while the machine is still running and catch large offcuts from the saw (if they fall on the floor and the saw returns to zero from an angled cut they can get caught under the saw housing or between the housing and the track and wreck them). This can be solved by using stands under the bit that will fall off and it can then be retrieved when the machine is stopped...
Karen
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Posted By fats van den raad Zoe The King was not unique in his magnificent wisdom. In a previous life I was involved in instrumentation and control maintenance. The company operated a call out system on a "if you're available, come in, if not it'll have to wait untill you are" basis. I was issued with a pager that I carried round with me, even when I went out, as we just installed a new control system and the operators were still getting used to it, and as such, a lot of problems could be solved over the phone. On this one night, I was out at my local, and found my skin outside at least a gallon of "Best" when the pager went off. I phoned the plant to be told by the supervisor that a machine had tripped out and they could not get it back up and running again, I have to come out. I explained to him my advanced state of embalment and that I could under no circumstances drive in that state. His suggestion was that he would send a taxi to fetch me. Needless to say, I declined his offer. 20 tons of Methyl Chloride, 20 tons of Propylene Oxide and 8 pints of Best Bitter should never be mixed.
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Posted By fats van den raad Request from a supervisor: "Can we cut holes big enough to get your hands through in that gaurd on the belt drive so we can get to grease nipple on the pulley?"
Duh!!!
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Posted By Paul Adams In a previous life.......... Guards on envelope stuffing machines for DSS have to be bypassed by engineers to make adjustments. Not permitted for operators to do this. Machine works in slow motion with guard up so engineer can observe mechanism and make adjustments. Engineers are classed as staff and therefore required to wear a shirt and tie. As they lean over to observe and adust the mechanism in motion............
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Posted By Peter Longworth I live in Burnley so although I didn't see this one everybody in this town knows about it. A local company that had processed waste plastic by shredding it into very small pieces. In order to increase production the guards were removed from a shredding machine. Needless to say the operaor fell in while loading the machine, the rest I will leave to your imagination
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Posted By Merv Newman I have a photo which I use in some training courses. Taken in the vehicule repair shop of a mine it shows a mechanic standing on the chassis under the raised tipper bin of a 40 ton lorry. One of the hydraulic cylinders used to raise the tipper bin had to be dismounted so they raised the bin and propped it up with a 6 foot crow bar.
I didn't get a photo of a similar situation : both hydraulic cylinders had to be removed so the back of the bin was lifted on the jaws of a jcb while two men worked underneath. As I walked up the driver saw me and called to the men. They stood back and smiled at me. Then the bin dropped with a crash.
Another shot I do have is of a welder, under a bulldozer, arc welding. His right shoulder is in a puddle of water. His left shoulder is on fire.
Worst one I remember was in a paper mill. After a break a few hundred yards of paper had built up on and around the machine. The machine was not shut down, just put on idle or held on a clutch. Production manager told a worker to get up on (4 metres high)top and clear off the paper. Worker said no it's too dangerous. Production manager decided to do it himself.
While he was up there the clutch slipped (or something) and he was carried through the steam heated rollers. Not killed but multiple injuries.
Worst practice I am desperatly trying to fight nowadays is the lack of lock-out on robotic enclosures. Technicians are convinced that a red card hung on the door will protect them while they are inside.
Discuss
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Posted By Robert.J The dust explosion relief panel was wedged shut on a mill in an R&D centre because the relief guage kept on indicating high pressure causing it (the mill)to fail to safe. The Exp relief filters were hardly ever cleaned!!!!! Luckily the operator went for a P, when he got back he didn't expect to be cleaning the plant for the next two weeks. The mill was intact but the relief system totally destroyed and hanging of different parts of the plant. He was "sacked" and didn't make a "meal" of it.
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Posted By peter gotch Heather
A friend of mine a sparky who did his apprenticeship at Ravenscraig. Had his own padlock. Isolated nasty big machine and locked off. Surprised to hear the machine start up. Foreman thought maintenance complete so took hacksaw to padlock.
At conference, with senior HSE person showing off first cut of his new video on how to guard a certain class of machinery. Continued videoing as engineer climbed inside perimeter fencing to carry out maintenance without isolating. Very proud to be able to show engineer being caught in the act.
At large factory to check nothing too seriously out of order before afternoon visit of very very very VIP. Interlocked guards on machine defeated and machine operating with guards open. "You will have those guards closed when VIP comes round" and I will revisit in 1 month to check interlocks reinstated. If not I will prosecute." Senior Company SHE person thought I was being unreasonable and complained to HSE.
At large factory for VIP visit. Fork truck driver shows his skills travelling through assorted mix of VIP, minders, media etc. I have front page of following day's paper in mind as I think "I know this FLT driver has been trained to stop until pedestrians are out of the way - they even have on-site qualified FLT trainers here".
At official opening of exhibition for public by another very very very VIP. VIP goes up staircase that has been declared unfit for public consumption by me and local authority. Thinking of front page of next day's paper again, particularly since very very very VIP due to open Government key institution the following day. Phew. Postscript, institution soon to be relocated in overbudget location. Tony Blair is not going to official opening, to chagrin of lots of VIPs.
Regards, Peter
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Posted By Alec Wood We had a visit from an OEM customer. They had had a big H&S drive recently and so much of the talk as they were being shown around our production facility was on the subject of safety. We knew they were coming and everything was gleaming and shiny, "days since last LTA" notices proudly displayed at the head of each line. I was an engineer then, and safety rep for the production area.
Fault diagnosis is done on live sets, we use a 240V isolation transformer and an earth free workstation for protection, but 24,000V still hurts.
As I was assisting a line technician diagnosing a defective set, one of the customer's engineers took interest in what I was doing and was photographing me working over my shoulder when my hand came into contact with a damaged portion of insulation on the HT lead. When I hit the 24kV live conductor I shot backwards, demolishing the safety screen and impacting the guy behind me destroying his camera and twisting his ankle. I hurt my back, cut my head, had arc burns to one hand and my knee and suffered disorientation, nausea and dizziness for six hours afterwards.
What should have been a very painful shock was almost a fatal accident, it took me around ten seconds to find out why - some moron (manager) with no technical knowledge had thought the isolation transformers looked untidy and removed them for the customer visit! Removing them had also earthed our benches since they were equipotentially bonded via the (isolated) earth conductor as an ESD precaution. Without isolation around two thirds of the circuit board was capable of supplying a lethal shock to anyone contacting it and an earth simultaneously.
I wonder what they told the customer reps who were there, or the one injured, I never did find out.
Alec Wood
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Posted By John Webster Operating a water treatment plant in Benghazi which required regular deliveries of concentrated sulphuric acid - used for scale supression. Normally this came by road tanker from Tunis, but for a while the Libyans closed their western border and had to rely on supplies shipped from Italy - in 30 litre black plastic drums.
These arrived in a grossly overloaded dropside truck & trailer, which pulled up alongside the loading bay. The local guys, working for the municipality, would knock out the pins, and the drums would fall off!! Once all un-burst drums had been lined up, it was the job of one of their number to pump out each drum in turn into the storage tank - wearing a tee-shirt, shorts, flip-flops and, of course, rubber gloves (can't be too safe).
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Posted By Merv Newman While browsing elsewhere, two other incidents came to mind :
1. I remember hearing about an accident at a teeside amusement park early this year : an employee took a shortcut to the toilets -across the roller coaster rails.
2. In my youth I served on the "chlorine gang" of a waterworks. The cylinders were delivered to us by lorry. To off-load them the driver threw an old rubber tyre on the ground behind the lorry then rolled the cylinders off the back. Every now and then one would miss the tyre ...
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Posted By John Allen While not an example of machinery safety the following near miss came to mind.
When I was an HSE inspector I was called to the site of the demolition of an old jute mill in Dundee. It had been reported that a worker had been seriously injured in a fall from the roof. On arrival at the site I was met by the demolition contractor, the police, and representatives of the site developer including his architect all of whom had been there about half an hour before me. There must have been 8 to 10 of us in total and we all trudged up to the top floor of this building.
The slates, sarking and purlins had all been stripped from the roof leaving only the roof trusses in place, something like a giant toast rack. Except of course for about three of them which had turned over throwing the unfortunate man over the side of the building to the ground below.
When I started to examine the roof it was immediately apparent that the remaining trusses could also overturn at any minute. As in many old buildings they were simply grounded in the top layer of masonry and with most of their weight higher up and all the purlins removed they were extremely unstable. Both the demolition contractor and the architect should have been aware of this as well as me and had had plenty of time to examine the site before I arrived.
I ordered everyone to clear the site and we had only just got into the shelter of the stair well when the remaining trusses overturned. Anyone standing on the top floor would have been killed. Two policemen had remained at ground level and just got out of the way of the falling debris in time.
Not surprisingly a report went to the Fiscal alleging several breaches of the HSWA.
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Posted By fats van den raad Getting a plant tour from the plant manager before embarking on a behavioural programme we came across the shift manager and two operators. The shift manager was standing on a walkway, one operator was standing on the middle rail of the handrail with his knees braced against the to rail,holding onto the belt of his colleague who was standing on the top handrail, leaning forward at an angle of nearly 45 degrees, furiously poking at something above with a 21ft scaffold pole. Underneath them was a near empty ore hopper, about 40 ft deep, with the ore level dropped so low that the screww feeder at the bottom was visible. What had happened was that the discharge chute feeding the hopper had become blocked, and as a result the hopper was in danger of running empty, which would have shut the plant down. Normal procedure would be to get the scaffolders to build a platform across the top of the hopper to give safe access to the blocked chute. This would however take too long and the hopper would have run out. The two operators decided on this course of action, but it was clearly condoned by the shift manager who stood next to them telling them to "be carefull".
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Posted By Merv Newman Heather,
I've checked my old text books and "squishy bits" in a rubber mill, especially if it is natural rubber, are no problem. Add an extra 5% sulphur. You might need a bit more chalk or china clay to soak up the extra moisture. Maybe 5 to 10 minutes extra on the cure time. Works every time
Merv
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Posted By Heather Aston Thanks Merv - lovely, I worry about where you're getting these text books from though.
You would be right if it were mixing compound from scratch, but this was a warming mill to break up the thick strip and form it into a thinner strip befoe feeding to the next process - temperatures probably not hot enough to disperse the squishy bits properly.....
Heather
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Posted By Merv Newman No worries heather, the sulphur and the extra cure time usually blacken the squishy bits nicely. If anything shows on the spc then run it back through the extruder before wire wrapping. Essentially you have to run the batch through before the HSE inspectors get on site. Quality control will tell you which customers accept this sort of off-spec batch. Otherwise it's an expensive burial with full rites. (how big is your batch size ?)
Merv
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