Confessions 24

[D Scullion]

Many interesting links shared detailing other peoples screw ups. Anybody on here willing to admit to their own?

Not trying to entrap anybody, don't admit to anything you could still get prosecuted for. Just want to hear a few funny stories.

I'll start: My first job in a small engineering firm with very little senior experience, almost every day was a near miss:

- Prototype 24 ton dump trailer, my first folly with hydraulics, on placement from uni. I designed the small hydraulic rams that open and closed a gull wing style back door to operate on the same circuit as the very large rams that lift the 24 ton laden body, without any flow controls. On first operation the back door closed so hard and fast it damaged the solid steel door.

- Ordered a laser cut sheet steel kit for a first production batch of a new product. Didn't realise AutoCAD was set so that all files were scaled 10:1. Received a delivery of miniatures.

- Made a tolerance error on the pivot of a large arm that moved a prototype piece of machinery into operating position. It seized up so tight only the hydraulic ram on the arm could turn it, couldn't even get grease into it. Prototype was on a tight deadline for a demonstration in front of a large group of customers which we had to go ahead with. Started to move the arm and the screeching from the pivot was mortifying. needless to say we waited until everyone had left after the demo before folding it back in again.

 

[waross]

That brings back a memory of a truck driver on his back in a snowbank with both feet in the air, trying to kick both boots off at once.
He had a piece of steel sticking out of the back of a dump truck and was trying to blow a hole in the 3/4" steel. When he hit the oxygen lever on his cutting torch a blast of molten steel and slag entered both of his boots.


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

 

[BridgeSmith]

Wow guys, I've only welded once in my life, and even I know it's always pants over the boots...

 

[D Scullion]

Talking of poor welding safety procedures, my biggest welding screw up was tacking up a prototype to speed things up for our fabricators to do the final weld. Spent the whole day doing hundreds of small tack welds while looking away or welding under an extended, gloved hand as I couldn't be bother lifting and lowering the visor every time. I won't make that mistake again, didn't get any sleep that night as it felt like a shovel full of sand under each eyelid

 

[dgallup]

While we are talking about other peoples screw ups, my 9th grade science teacher was talking about safely using chemicals. He said that if you accidentally spilled a little acid on your hand, you should not go running down the hall screaming. Instead, you should go over to the sink and rinse the acid off. At this point he proceeded to demonstrate pouring sulfuric acid on his hand, calmly walking to the sink, opening the tap and nothing came out. He quickly ducked down under the sink to see if the valves were shut off down there. They were not. He then went running down the hall screaming "They shut the water off!".

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[RobertHale]

I worked for a plumber/site civil contractor while I was in college. One day we were laying CMP at a new BP. That morning, I had put on a pair of old work jeans with a frayed bottom hem. My boss told me to go over and cut a length of 24" CMP. We used a demolition saw with an abrasive wheel to cut the pipe. About halfway through cutting the pipe, I got the feeling "damn it's hot," I pulled the saw out of the cut intending to roll the pipe and continue on when I looked down to see my pants on fire. I made the further mistake of trying to tamp out the flames with my hand. In retrospect, I was pretty much screwed with any course of action.

Robert Hale, PE

 

[BridgeSmith]

I once worked for a mechanical contractor for a summer. One day we were tasked with making a few connections with 6" PVC pipe with glued connections...in an access tunnel. That was a fun afternoon...or at least it seemed so. We even skipped our afternoon break, 'cause, heck, we didn't care! About half an hour after we got done unintentionally sniffing glue all afternoon, the massive headache counteracted all happy feelings.

 

[EdStainless]

I worked overseeing a foundry operation.
I usually wore cotton or wool trousers, but didn't really think too much of it.
On a hot summer day a wore a pair of lightweight synthetic ones.
Standing on the melt platform the radiant heat from the pour (Co based, 3200F) caused the synthetic to ignite.
Fortunately I had gloves on and I was able to just reach down and pat it out.
I just lost about 1/2 of the right leg up to mid-thigh.
I went home that eve and tossed all of my synthetic pants and shirts.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[CWB1]

Fires, burns, and melted clothing/objects are simply a part of hot work. In college I took the full welding series and became certified then spent a summer welding with union ironworkers erecting my alma mater's new student center. If you want to develop some real nerve then try welding (and the requisite catching yourself on fire) while balancing on a beam 50' up.

 

[Agent666]

In a previous life, I worked at a place where they had mechanics for maintaining plant.

One day they were repairing a van, one guy was welding on it while the unknown to him another guy was drained the fuel lines.

Naturally the large bucket they were draining the fuel into caught fire under the vehicle. Not too bad they thought, and managed to quickly pushed the van out of the workshop with no issues. But now they had a large vat of burning petrol going hell for leather in the middle of the workshop, flames licking the roof. People started panicking, running around trying to find the fire extinguisher.

The next move one of the original guys took was to naturally try to kick/nudge it out the door, one slosh of the fuel later and the man is fully on fire running for the exit engulfed in flames. Those present managed to put him out after a bit of rolling around and being doused with a fire extinguisher which finally turned up.

Natural selection almost took hold that day. He was burnt a little on his legs and face, but no lasting damage, seemed to heal up ok. Never underestimate the stupidity of others under pressure.

 

[TehMightyEngineer]

Performing construction observations on an overnight welding crew at a large paper mill; hanging out while they torch out some damaged metal to replace it. Torch operator sees me reaching for a piece, says "watch out; that's still hot".
"Duh, I got gloves on", says I.
...I was wearing my finger-less mechanics gloves that night.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[DAVIDSTECKER]

Years ago when I worked for a company that built truck based Explorational drill rigs we had a rig that was about 10 years old come back in to be placed on a new truck.
This rig had a 370 CFM rotary screw compressor that was powered by the trucks drive train via a split shaft gear box which is what wore out the old truck.
There was only 50,000 miles on the odometer but they ran the truck all day running the compressor, actually set the engine on fire about 7 times over the years.
So the big day came when the new truck was done and it was time to test the compressor drive.
The compressor was located just behind the cab up on the truck bed. The separator tank was on the drivers side.
Since the speed of the engine was controlled in the cab, I was standing outside the cab with the door open when the 3" hydraulic hose that was used as an air line coming from the separator bust pretty much right in my face.
Fortunately it hadn't been running that long and the 15 gallons of transmission fluid that blew out at me wasn't hot yet.
I think the temp gage on the tank went to 450 deg.
Any way I wasn't hurt, but when I looked in the cab there was tranny fluid dripping from everywhere in the cab even the ceiling above the passenger's seat. Some how the fluid made over a 180 deg turn.
That cab and everything around me was drenched, especially me.
It turns out that the shop had re-used all of the 10 year old hoses that were cracked and brittle from the high heat of the compressor discharge.
I had such an adrenaline rush the rest of the day I could fell my hair trying to stand up and few other side effects as well.

 

[Stephen Nuchia]

I set my brother on fire once. He was about 6, walked into my "lab" while I was doing something pointless and destructive with a gasoline torch of my own devising: a little gasoline in a test tube with a stopper and a 90 degree glass tube through the stopper. Heat it briefly over the Bunsen and pass the outlet by the flame to ignite it and while the liquid boils you have a nice flame thrower. I was wearing my welding apron but of course Joey wasn't. I jerked when he startled me causing a bolus of boiling gasoline to pass through the tube and then through the flame at high velocity, proceeding from there to his shirtfront. I embraced him muy pronto to extinguish the fire against my apron and thought we were cool but his lack of eyebrows gave the game away.

It not engineering, rather the opposite actually, but it was definitely a failure.

 

[Stephen Nuchia]

I don't have any good design error stories to tell but I've failed to recognize the flaws in systems for too long a few times. One plant we worked in had an "old" and "new" medium voltage network with a few big medium voltage motors and a lot of 480v, fifteen or so substations. The double-ended LV substations were fed from both MV systems and the MV lineup had a tie breaker in middle that was normally open.

The old system was solidly grounded, the new system was resistance grounded. And to start the mill motors with the mill full they had to close the tie, neither system was stiff enough alone. One day there was a ground fault on one of the resistance grounded feeders and a solid-ground substation on the other side of the plant blew up.

We had to tear the bus out of the back of the victim substation's MV section, it had arced to the enclosure all along its length. So I had a lot of time to think about how it could have happened. It wasn't until I started checking the specs on the (spent) lighting arresters that I finally twigged. Ground one leg of a resistance grounded 4160 and you get 4160V phase-to-ground. But the lighting arresters on the solidly grounded system expect a maximum nominal 2300V phase to ground.

There was another burndown in the same plant a while later. I had retrofitted digital relays on the MV breaker that burned just a few months earlier so I was keenly interested in the cause. There was water in the compartment, standing on the breaker frame, from a roof leak. But the digital relay had waveform data for the event and I could trace the progression of the arc half-wave to half-wave but I couldn't find any way to blame it on the water. It wasn't until we got the breaker back to the shop and one of the other guys discovered an important part was missing that the data made sense.

The "old" system in that plant had originally been a main-tie-main and was fed from two 5MVA transformers, with the tie replaced by a solid bridge. When I later went back to prepare the data for an arcflash study I realized just how scary that lineup really was. The high side of those transformers were from the dead end of a 115 kV transmission line and less than five miles from a 2 GW power plant. The only saving grace was the high-side fuses.

Different plant, not so many big motors and more modern overall but one of the substations had an oddball low side with no 480V main breaker. There was a 480V tie circuit from another substation that was normally de-energized ... except when doing high-side maintenance. I was looking at the highside bus with my boss, standing on the substation gravel bed with the doors open on the powerhouse compartments. We were just eyeballing it, planning future work, when I reached out to point at something. Made contact with a busbar and got a tingle, like a static shock more or less. It wasn't until some time later I realized I'd touched a 4160V bus backfed through the 480V tie. Dry gravel and the ungrounded source saved me. That was the beginning of the end for that job for me, I'm a developer, not an operator, and my mind isn't sufficiently checklist-oriented to work long term in that environment.

 

[itsmoked]

That would indeed be a decision nexus for sane people.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

I was in Canada when I got a call from the owner of an ice plant in Central America.
One of his ice machines was tripping into harvest mode several times a minute.
About 5 local experts had been unable to find the problem. Some refrigeration men and a couple of electrical engineers had been all over the controls but couldn't find the cause.
The owner sent me a round trip ticket.
There was nothing wrong with the controls.
A liquid line filter was almost completely blocked off.

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

 

[RVAmeche]

We were commissioning a brand new air compressor / desiccant dryer system. Start up the system and the dryer is leaking at almost every filter; the cardboard gaskets were no good so they were replaced. Try again and the low pressure control valve on the dryer discharge isn't working right. I'm trying to help the vendor tech but he seems to be almost useless, so I grab our controls engineer who's at the site doing programming. The solenoid valve on the control valve was plumbed completely wrong. I'd love to know how it passed the factory tests that it was signed off for.

 

[LionelHutz]

Bill, that reminds me of our service tech who took a 2.5 hour drive to a site. Once there, they took him out to the starter while telling him how it won't do anything when they give it a start command. He looks at the door, pulls out the e-stop button and tells them to "Try it now."

 

[waross]

I was working near enough to see this drama unfold;
A fairly sophisticated loading ramp.
Bear in mind that this loading ramp could work with just one momentary push button, but this had a lot of added features.
There was a hook that engaged the trailer to prevent it from moving as it was being loaded or unloaded.
There was a traffic light to indicate to the driver when the hook was engaged or released, There were inflatable bags to seal around the trailer to keep the weather out of the building, and there was a button to start the loading ramp.
When the truck pulled away, the ramp would fall by gravity until it closed a switch that started a sequence to raise and park the ramp.
That switch was called the "below horizontal switch".
Because of the name of the switch, someone had it set up so instead of operating at the bottom of the ramp travel, it operated as soon as the ramp went below horizontal.
The system was controlled by an expensive PLC with communication back to the main computer.
It worked OK for most trailers, but when a low trailer came in, the ramp would operate the switch before the ramp came to rest on the trailer deck and the ramp would park itself.
Even worse was when a trailer was just a little bit too low. The ramp would deploy but as soon as the weight of a forklift truck caused the trailer to settle a little, the switch would activate and the ramp would try to park, with a forklift truck sitting on it.
One day, we saw an old hand teaching some of the new guys how to unload a low trailer.
He pushed to start button and then put his hand on the main power disconnect switch.
The hook grabbed the trailer.
The traffic light went red.
The ramp raised.
The lip extended.
The ramp started to descend.
The old hand said;
"NOW" and turned off the main power.
The ramp continued down under gravity until it rested on the trailer deck.
They unloaded the trailer and then turned the power back on and the ramp parked itself and the hook disengage and the traffic light went green.
"Ya, it's just like the ramps that they put in a couple of years ago on the other side of the plant."
End of the story?
No.
A couple of hours later, a couple of electricians would show up with a work order that had been generated automatically by the main computer looking for a reported power failure.
We just shook our heads.
Several thousands of dollars worth of sophisticated PLC that must be turned off to function properly.

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

 

[byrdj]

My all time classic problem similair to Lionels story.

I got a call from a Plant I once worked regularly, the plant had changed owners and I had been there in a decade or so, BUT my name was all over their outage reports.

So when this problem arose, I got a call. The reported problem was "we can't pick up load" for the steam turbine/generator. So back and forth with things to look for and return calls, it hit me the unit was tripped and thus not even spinning.

So now the same thing but this time why can't they reset. (there is a BIG diffenrence in expected problems between cant pick up load and not resetting)

It was getting a point in the confussion between what I wanted them to check and report and what they were doing. I am getting extremely aggrovated with my contact (a Shift Supervisor) and told him "lets just start at the beginning"

"Do you have your oil pumpS running?"
this pissed him off and replied OF COURSE we have A pump running!
but I pushed and explained that there were two oil pumps, one only provided bearing cool down and the other provided the hydrualics for the controls.

there was a silence....then he said he would get back with me and hung up!

Not hearing back, I called the purchasing agent number I had and the new guy said he was not aware of what was going on, but the unit was back on line.

 

[wayne440]

Not mine- but I did find and fix it. At an un-named public safety dispatch center, we have a utility failure. The diesel generator starts, and the dispatcher says "I hope the power comes on before that generator quits...". I ask why he thinks it will quit and the reply is "It always does, it will run for a little while, then shut off". Ten minutes later I find that the day tank pump was not powered by the generator it was intended to serve - it only worked when the utility was on.