WWOED? IE: What would other engineers do?
WWOED? IE: What would other engineers do?
(OP)
If you have a material you know to be produced to both ASTM A307 Grade A (no Fy specified, Fu >= 60ksi) as well as SAE J429 Grade 2 (Fy >= 57ksi, Fu >= 74ksi), would you be comfortable using the Fy = 57 ksi for the purpose of structural design?
It is really bothering me, and I want other Engineers' opinions on whether or not that would be acceptable practice. Sorry for the double thread, but I really want to know your opinions.
It is really bothering me, and I want other Engineers' opinions on whether or not that would be acceptable practice. Sorry for the double thread, but I really want to know your opinions.






RE: WWOED? IE: What would other engineers do?
RE: WWOED? IE: What would other engineers do?
Note that Portland Bolt has SAE J429 Grade 2 with a yield strength of 57 ksi for diameters of 3/4", or less. For diameters over 3/4", yield strength is 36 ksi. You did not mention the diameter being considered. Typical applications of SAE J429 are listed as automotive and related industrial (no mention of structural use).
From Atlanta Rod there once was a Grade C of ASTM 307 (now superseded by another spec). Tensile strength is shown as 58 to 80 ksi, yield strength is 36 ksi. ASTM 307 is commonly used for structural purposes.
Based on this (circumstantial) information I would assume a yield strength of 36 ksi.
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RE: WWOED? IE: What would other engineers do?
I know the product, and I know it to be cograded A307 A and SAE J429 Gr 2. The question is whether you would rely on the Fy = 57ksi when you know it is present, but comes from the automotive side of the cograding.
RE: WWOED? IE: What would other engineers do?
But the result is good for only that run of that particular heat cycle for that particular mill.
Why do you want to save a few pennies of material cost by jury-rigging a specification up higher than it could be? How do YOU guarantee ALL of the rest of the steel bought from anybody else is as good as 57K yield and not 36K yield? (Hell, for that matter, how can you assure yourself that ANY steel purchased from an unknown re-melted mill in China is even 36K yield? )
RE: WWOED? IE: What would other engineers do?
Juston Fluckey, SE, PE, AWS CWI
Engineering Consultant
RE: WWOED? IE: What would other engineers do?
My preference would be another material like ASTM F1554 Gr. 55 if it is available in the length needed. There are other materials that might work like A572, except don't think this specification covers the thread dimensions, so the pedantic may want to specify the appropriate standard for the threads. Another choice might be A193 gr B7 except the standard may not include a minimum yield strength.
RE: WWOED? IE: What would other engineers do?
It's an unusual situation, and I'd take the extra steps required to make sure the client understands what he needs to procure -- but that said, once you have it, I'm certainly comfortable with using the higher of the two minimum strengths.
We have this happen all the time with Korean or Japanese fabrication -- material dual certified to ASTM and JIS specs. Sometimes it turns out to be really handy to have an extra 10ksi of capacity in the back pocket, when the client changes something down the road.