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Design/Weld Failure

General welding questions that dont fit in TIG, MIG, Stick, or Certification etc.

Design/Weld Failure

Postby Coldman » Thu Jul 20, 2017 11:24 pm

I just read a report about a single span canopy/truss failure on a construction site in the UK.
Here is the link to the report, interesting reading particularly about the series of actions/events that contributed to the collapse.
http://wtia.bmetrack.com/c/l?u=71FBC3F& ... Bwgn&seq=1
Flat out like a lizard drinkin'
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Re: Design/Weld Failure

Postby Poland308 » Fri Jul 21, 2017 12:18 am

I know during some procedures they require third party inspection of tack up, and between all intermediate passes. Seams like a PITA at the time, but it can literally save lives.
I have more questions than answers

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Re: Design/Weld Failure

Postby weldin mike 27 » Sat Jul 22, 2017 3:20 am

During my Inspection course, they spoke about two structure failure that were caused by incorrect welding due to new style materials being used, crack sensitive low alloy steel in particular. No one knew the need and or importance of preheating in the manufacture of the King st bridge in the 60's in Melbourne that failed, luckily it only fell about half a meter at one end, and no one was injured.

The other one was a roll on roll off wharf in the UK, it was in recent years (90s?) and the welding procedures weren't followed, causing it to fail and fall into the water, causing a death of a worker.
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Re: Design/Weld Failure

Postby Rupes » Sat Jul 22, 2017 4:50 am

"thats how we've always done it"

Once dodgy connection and the whole truss unzips. How many engineers went through the plans for this?

The one below re the cantilever transfer beam not reaching out far enough to get under the 5 storey load its suppose to carry is pretty scary. The cantilever probably isn't even required, just looks good or allows for a few dozen meters of retail space or something.
Nowadays people know the price of everything and the value of nothing... Oscar Wilde
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Re: Design/Weld Failure

Postby noddybrian » Sat Jul 22, 2017 3:37 pm

@Welding Mike - if that's the one I'm remembering ( 1994 ) it caused 6 deaths & 7 with what they call " life changing " injuries - although the collapse started with a weld failure & they wanted to pin it 100% on the makers who had used some non traceable steel supplies it went years without adequate inspection by port authority & the actual cause was retarded design in the first place - happened about 20 miles from me - there is one closer that is still in use despite having corrosion holes right through major structural components - they don't want to do anything about it as the area it serves is soon to be re-developed so it's not seen as cost effective ! go figure
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Re: Design/Weld Failure

Postby weldin mike 27 » Sun Jul 23, 2017 12:47 am

I was hoping you'd have some info on it. I know that in use inspection is expensive but it would inevitably save lives.
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Re: Design/Weld Failure

Postby noddybrian » Sun Jul 23, 2017 9:22 am

I can probably find some links to the incident if anyone is interested - inspection is expensive but the main problem with it in these situations is often there is no redundant back up so time out of service is a factor along with most inspection methods require bare metal so all protective coating must be removed & replaced afterwards - this is somewhat time consuming & weather dependent so has to be done in the summer months when the most passengers are using it - the railways can get round this by doing most work at night when there are fewer passengers & public holidays plus they can lay on a bus replacement which the ferries can't ! sadly around here we have had quite a few avoidable incidents - some remembered more than others such as the sinking of the herald.
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