Which standard for steel fabrication?

[posture]

Hi

I’ve been tasked with improving the quality of drawings produced by our CAD team. One of the areas I want to look at is introducing a standard to guide the “production” of the drawings. Basically the guys take a very hit and miss approach to dimensioning, layouts ,tolerances, detailing etc. I want to get something that we can use as a reference and put some structure and repeatability into our drawings. We design pressure vessels, sheet metal housings and skids : anything from a 1000mm tall, 150mm dia vessel to a 6m x 3m x 3m skid. We don’t need to address things like surface finishes or the various fits. What I think we need to address are things like basic dimensioning, calculating tolerances correctly and providing sufficiently detailed drawings so that the fabrication shop can cut and weld up the various components.

After some looking around here and on-line, the standards all seem to be related to machining or similar. Are there any standards related directly to fabrication and piping etc or are the gear towards both?

I’ve been through many threads that discuss the various ISO/ASME standards. Although the discussion are pretty detailed, I’m still left a bit unsure of the relevance of any of them to what we design.

Can anyone point me in the right direction?

Is mise le meas

Posture

 

[ctopher]

I'm not clear on which you want.
You can them here.

http://www.asme.org/kb/standards

http://www.iso.org/iso/iso_catalogue.htm

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[DeanD3W]

posture,
ASME Y14.5 does provide what you need. I've heard things like "oh, we don't use GD&T here because we do sheet metal parts", but that isn't a valid way to look at controlling the imperfection of mechanical parts... Whether the part is machined, molded, cast, forged, or fabricated the methods in Y14.5 will work.

ASME Y14.8 has additional methods for "Castings, Forgings, and Molded Parts". Discussion of standards catered to other manufacturing processes comes up once in a while. In my opinion, sheetmetal or fabricated parts are provided for well enough with Y14.5. Not to say that Y14.5 doesn't need to be improved... All standards will always need improvement (I think I can safely say "all" & "always" in this case ).

While Y14.5 should provide 90% or more of what you need, you may run into opposition regarding its implementation. Controlling imperfect geometry is a detail oriented endeavor and some people will say "we just need to keep things simple"... Those will be the ones with specs on their drawings that are ambiguous. GD&T has been developed by well experienced and very smart people, starting during WWII... For some to come along now and say that it is not necessary has to be called absurd... The methods in Y14.5 may be avoided well enough if tolerances can be very loose relative to the level of precision that the manufacturing process will typically deliver. Maybe Tonka trucks can avoid the use of good specs, but I'm quite sure that Freightliner Trucks would suffer lower profits if they tried to do so.

Dean

http://www.d3w-engineering.com

 

[MintJulep]

Either ASME or ISO standards are perfectly suitable.

However, if your designers, engineers and drafters don't fundamentally understand what is necessary to make a good drawing then throwing a copy of a standard on the desk isn't going to fix the problem.

 

[posture]

thanks for the replies all. Just what I was looking for!

Posture

 

[KENAT]

Posture, if in the US then I'd agree that ASME Y14.5 the relevant spec. Though it appears biased to machining it is adequate for sheet metal too - I haven't really done piping but I'd think the basic principles would apply so long as you aren't talking more of a 'construction' type environment.

Mint also makes a good point, while the relevant industry spec is a foundation to work on, it won't by itself solve all your problems.

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