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Calling out Welds for a fab shop 1

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vonsteimel

Mechanical
Oct 19, 2010
132
Greetings,

I do a fair amount of drawings which require weld call outs, most of which will end up being made in a fab shop environment. Most of the welders are not certified.etc and do not know all the the weld symbols.

I usually just use the "Fillet" weld symbol to call out welds as its the most commonly known it seems. But when it comes down to it, its not correct and just looks bad when a professional engineer/drafter/welder.etc does get their hands on it. For instance, say I call out a seam weld with a fillet symbol.

Or sometimes I'll just use a leader that reads "Spot weld every 1.50" .etc

This has to be fairly common in smaller mfg & fab shops. How do you recommend handling it? Should I just call them out by the book and let the fabricator figure it out?
Thanks,

VS
 
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I used to work in a marine exhaust shop. Few certified welders, etc.
Our fab drawings typically had _no_ weld symbols on them.
The default was 'weld everything everywhere'.

... which made it difficult to tell them to _not_ weld a particular feature.

I drew up some gas turbine housing seals that were beautifully laser-cut from 14 gage sheet. They had tabs and slots cleverly arranged so that the part with the tabs could be formed by hand into a quarter circle of 14" radius, and inserted into slots between two quarter circle sideplates. I put a plug weld symbol on the assembly with an underflush contour mark, so that they would just do a nice neat TIG weld inside the slots, melting the end of the tabs, which didn't quite extend all the way through the tabs.

The experienced fabricator did a nice job. ... of filling and 'buttering up' the slots, and then grinding them flush with a 60 grit snag grinder. They looked like shit, of course, and he did this despite my humble request, scrawled in red on the print, to call me for instructions before starting assembly. I hadn't ordered spares for him to screw up, so that's what we shipped. We didn't get a repeat order. Not my problem anymore.


Oh. Sorry. Back to your problem. If I had it do over, and I did, at another shop for another product, I'd still put the proper weld symbols on the drawing, to the best of my ability. If it's a shop where nobody knows how to read the symbols, let the shop foreman mark up the fab prints in whatever language works for them.

In summary:
The drawing/file that leaves your hands should be sufficient to cause production of the part you want >by a competent shop<. Adaptations for non-competent shops should be handled within those shops per their local custom.












Mike Halloran
Pembroke Pines, FL, USA
 
In situations like this I tend to use a combination of ANSI weld symbols and really thick sketch segments on my 2D drawings to highlight were the welds need to be. It's also good to supply something for the shop to interpret the weld symbols with, like this.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?
 
WV, I'd strongly recommend using correct weld symbols, with weld sizes, spacing, etc, and the process called out in the tail if needed. You may surprised at how much this is appreciated on the shop floor, and if these are sub-contracted it's really the only way to get your requirements met.

Mike, I feel your pain. Reminds of "Oh, the parts weren't quite to print so they didn't fit the fixture. I ground the fixture so they would fit."

Regards, Diego
 
Yeah I'd go with what I think others are saying. Make the drawing weld symbols per the standard then if need be fine a way to help the fabricators understand the symbols.

Might be extra detailed sketches and/or notes on the drawing though that would probably be my last resort. How about a separate detailed travelor/work instruction/pseudo weld process or whatever you like to call it? Of course an extra document to look after has its own draw backs too.

Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484
 
Fabricating anything professionally should be none correctly, especially in your "area", because if there is a failure in the part and injuries occur I grantee the first place any legal action will look are the fabrication drawings!
 
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