Drawing material callout: "material XYZ or Eq." 6

[just_some_shmuck]

For years, my company (consulting engineering) has included "or Eq." in drawing material callouts (IE "Material: ASTM A36 or Eq.")

Is this wise to do?

How will a fab shop interpret "equivalent"?

If I happen to suffer from momentary stupidity and specify a tube made from A36 I am fine if they substitute A500-B. If I specify a C-channel as A36 and they substitute A992-50 I am OK with that too. If I specify A514-B and they substitute A36 (much weaker), then I am NOT OK with that.

What are your thoughts on this?

 

[Christine74]

Here's a link to a Bill of Materials for a heat exchanger prepared by a reputable manufacturer that's also an ASME stamp-holder:

https://www.lcec.com/objects/catalog/product/extras/106772_1.pdf

The last three pages are the BOM. As you can see, every pressure-containing component a the specific ASME material grade called out, but there are also a number of generic material call-outs like "STN.STL", "304 S.S.", and "STL."

While I don't agree with their use of "STL." for the lifting lugs I think this is completely reasonable for the components that don't see any appreciable loads. For corrosion purposes the tube bundle components exposed to the shell-side fluid need to be 304 stainless steel, but no specific material grade is specified because it doesn't matter.

I've reviewed many BOMs over my career and I don't recall ever seeing one that didn't use a few generic material call-outs.


-Christine