welding, the draftsman and thefabricator.

[Enigma]

What's the general conensus on how crazy to go with welding symbols on a drawing?

I come from a background in a consulting engineering firm, where our fabrication drawings typically did not detail every little piece, but had all the information required to build the component. Unless there was some explicit welding requirement, such as seal welds or whatnot, we rarely ever used standard welding symbols or annotations. The details would usually show a 'picture' of a fillet weld, but the actual welding size, length, etc. was left up to the guy who actually knew what he was doing, the welder/fabricator.

While I have a fairly decent understanding of welding, drafting wise I was only ever taught how to show symbols and calculate strengths etc, but never any actual welding seminars or such.

So in this new job, where we are somewhat of an OEM design company, but send our drawings out for bids, I have kept my usual practice of calling up the welds with a general note on the drawing unless a specific procedure is required.

So the question is, I guess, is should I put on weld notes using 'my best educated guess' as to how to stick this metal together or let the shop figure it out?

[DANIEL]

I do exactly what your talking about, I let the shop figure it out, thats what we are paying them for, just make sure that its clear that the fabricator is resposible for the weld.

[SLW210]

An Engineer should determine the weld size, length, type, etc., not the shop or the draftsman, there are liabilities involved.

 

When I was engineer for a company that built and designed, we always used a general note in the titleblock for 1/4" continuous filet U.N.O. (Unless Noted Otherwise). Anything else we marked at the weld with proper weld symbols and info.

[stevsmith]

If my company received a drawing with no weld specification on it we would assume that it is fully welded min 4mm, if we preferred stitch welding we would consult with the customer first.

I agree with SWL210 on what he says regarding workshop employees deciding what welding is relevant / required, this should not be the case. This is the engineers responsibility.

 

U.N.O is a great addition to any title block for any item, eg tolerances, weld sizes, fasteners, etc.

Also add a note saying "If in doubt ASK", but then again, nobody ever does.

[Tankman]

Most good fab shops, know what to do and how to.

But, if you're producing drawings, why not use the welding symbols?

 

[ReMark]

We have our own fabrication shop so our drawings only call out welds that are non-typical. It may, for example, be a new material that we're using so we consult with the manufacturer about the best welding methods/materials. I do keep a copy of Finch's "Welder's Handbook" by my side just in case.

Edited November 3, 2011 by ReMark

[Bill Tillman]

There are many things left off of drawings all the time. Otherwise the shop and the field would never have anything to complain about...right. But because of the liabilities involved with welding, or any structural connection be it bolted, welded, rivited...whatever, there must be standards.

 

I once knew a senior structural engineer (RIP) who put it best in a meeting we were having about this type of stuff where he told a packed room of people who were arguing over what was to be assumed on a drawing. He said "You know that, and I know that. But this drawing doesn't tell me that. Therefore it's not correct." The whole room went silent because we all knew he was right. The drawings should have every friggin piece of information on them necessary so that no one should have to make assumptions about what is to be done. We all know reality is a little different.

[SLW210]

No need to mark every single weld if they are all the same, they can clutter the drawing if there are a lot. Just like if all holes are 13/16"ø you should use a note "ALL HOLES 13/16"ø U.N.O.".

 

If all welds are different and there are enough that weld symbols would clutter the drawing, do welding details, even on a separate sheet if necessary. Last place I worked before here, I was a Weld/Quality inspector, some of our assemblies had a lot of parts and use three assembly drawings, a drawing with item/part numbers, a drawing with dimensions and a drawing with all the welding info including enlarged details.

[DANIEL]

1. all welds to be per aws standards unless noted otherwise. No gas bubbles, remove scale, clean & dress welds as required.

or even something like this

1. all welds must be full penetration, cleaned, gas tight and bubble free per aws d1.1.