Return to index: [Subject] [Thread] [Date] [Author]

RE: Calling out/specifying tubes

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Title: RE: Calling out/specifying tubes

Wow, Harold. That's a lot of questions for a Friday! (-: Some answers below.

>You just brought up a list of HSS ASTM designations.  I just had occasion to
>check on the availability of A618 and large thickness A 500 and found that
>no one can supply them as the ASTM is written....

You are correct. Although ASTM A500, A501, A618 and A847 all cover HSS, to my knowledge, only A500 is readily available, unless you want to order a mill quantity and verify with the mill ahead of time. You're smart to emulate Diogenes. (-:

>One major manufacturer of A500 is not in compliance because of thick
>wall shapes they cold form 2 C shapes and weld them together using sub arc
>not electric-resistance-welded as stated in the A500.  They also have
>problems with the periphery and the specified inside radius per A500.

Lanny Flynn, our (AISC's) Far West Regional Engineer was the first smart cookie to figure this out and alert me to the problem. Until his call, I was fat, dumb and happy. We are currently seeking a solution. This may mean a change to ASTM A500 to allow greater peripheries or a new ASTM spec to cover HSS with peripheries that exceed 64 in. Or another solution may emerge.

>The AISC LRFD manual lists the A618 as more weldable than the A500.
>Is there something else in weldability of which I am not aware?  The CE of
>an A500 is 0.32.  The CE of A618 is 0.37.  Both are weldable, but I would
>not perceive A618 to be more weldable than A500.

I guess if it is weldable, it's weldable...right? "More weldable" is probably a badge of esoteric distinction. I'll bring this up as we revise the Manual. Thanks.

>How available is angle and channel stock in a Gr 50 material?

It's a chicken and egg thing. I suspect that most angle and channel product today labeled A36 has a strength level that would meet the requirements of A572 grade 50. Essentially, it's just like the dual-cert material situation that existed with wide-flange shapes before ASTM A992 was introduced for wide-flange shapes. But until the mills that produce channels and angles actually start certifying their product to A572 grade 50 regularly, I'd stick with A36 in those shapes, unless you know you can obtain then ahead of time.

Hope this helps.