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Old 07-21-2016, 08:32 AM
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Default Lucky he didn't die

With the new organization this is the best place I could think of for chain pull metallurgy and mis use during fabrication. Move to can if you think otherwise...

Yesterday at work an EE had a near miss as this chain pull failed, and since safety latch wasn't engaged, had enough energy to shoot remaining section of chain and hook up into and made an impression in cieling of plant about 30 feet above him.

Root cause was using a 4' cheater as the head he was trying to put on the shell was undersized and required a little more than normal. Another EE states he would normally put another chain pull on and tighten them up bit by bit.

The little piece of chain that was severed I two places ( which is really why I'm interested, is this type of failure rather than one tear and pulling out.) is still MIA.

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Old 07-21-2016, 09:16 AM
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Quote:
Originally Posted by weldor2005 View Post
With the new organization this is the best place I could think of for chain pull metallurgy and mis use during fabrication. Move to can if you think otherwise...

Yesterday at work an EE had a near miss as this chain pull failed, and since safety latch wasn't engaged, had enough energy to shoot remaining section of chain and hook up into and made an impression in cieling of plant about 30 feet above him.

Root cause was using a 4' cheater as the head he was trying to put on the shell was undersized and required a little more than normal. Another EE states he would normally put another chain pull on and tighten them up bit by bit.

The little piece of chain that was severed I two places ( which is really why I'm interested, is this type of failure rather than one tear and pulling out.) is still MIA.

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Yup, there is a reason those things do not have 4' handles.
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Old 07-21-2016, 10:04 AM
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This is the type of tank. For fit up, generally we thread the eye thingy (pic 1) to top of head, and use 3 chain pulls. 1 goes through the eye and acts as 2, the other two hook to eye, thus giving equal force in four quarters while pulling tank bottom and head onto the shell.

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Old 07-21-2016, 11:53 AM
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I think it is time to develop a hydraulic press for doing that...

Or wait until someone kills themselves...
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Old 07-21-2016, 12:01 PM
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"Lucky he didn't die"

Well he should at least gotten a bruise.

So every time the weather changes, he'll be reminded of it....

And a week off without pay.
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Old 07-21-2016, 12:05 PM
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I'm trying to figure out how you pull on the tank. At first I thought you were using the chain fall to draw the two ends up tight against the main body but I don't think that's the case. If the chain fall was inside the tank the broken dits wouldn't have been able to reach the ceiling. I'm also sure you're not wrapping the chain around the tank end to end so yeah, I'm stumped.

It's also really weird how those links broke. I've seen lots of chain breaks in my day and they usually let go at the weld or split on one end. In the pictures you posted it looks like there's actually a little section of metal missing from the link...
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Old 07-21-2016, 12:15 PM
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Quote:
Originally Posted by LKeithR View Post
It's also really weird how those links broke.
Considering the assembly "method" is less than "ideal" or simply put, fucking
stupid. I am guessing the chains have been damaged in the past, and decided
to fail this time...
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Old 07-21-2016, 12:16 PM
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Quote:
Originally Posted by LKeithR View Post
In the pictures you posted it looks like there's actually a little section of metal missing from the link...
Like it got arc-ed on before.

The ground fell off, the current arced to the weldment through the chain
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  #9  
Old 07-21-2016, 07:10 PM
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The other chains should be presumed overloaded and scrapped along with the failed chain. As in "torch cut so some goober doesn't dream of using them".

This may help figure your loads and selecting gear with sufficient leverage and safety margin. There's probably a safe way to do what you want but overloading relatively lightweight chain ain't it.

http://www.thecrosbygroup.com/resour...-lifting-free/

Check out different Grades of chain and be sure everything you use in the system is of suitable strength. You could contact Crosby tech support if in doubt and send pics of how you were laying the chain.
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Old 07-22-2016, 06:34 AM
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The assembly method is sound as that is the way three different tank shops in this area do their larger tanks. We do have hydraulic headers for 24" and under.

We have determined we will be going with a chain fall that has a slip clutch in it.

https://youtu.be/GYJuPXax1SY

This way I don't care if they use a cheater, they wont get anywhere, wont come close to over loading chain. Oh and of course he denies using cheater, even though there are marks on the handle...

I will try and get a picture of one with chains on it to show you Kieth.
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