A992 Cost vs. A36 2

[MatthewR]

Hi, I am designing a truss using rolled angles and I have the option of designing for A36 or A992 grades. There will be a slight savings in weight using the 50 ksi A992 but I was wondering how much more it would cost than A36. Does anyone know the cost per lb of A992 vs A36 or where I could find this information?

Thanks in advance.

 

[steellion]

A992 is the standard steel type for wide-flange shapes.
A36 is standard for angles.

You will be paying quite a premium to specify A992 angles, if you can even find a mill that will produce them. Stick with A36.

 

[HgTX]

You could look into A 572 Gr. 50.

Hg

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[MatthewR]

@steellion
I know that per AISC 13th Ed, A992 is an "applicable material specification" for angles, "the availability of which should be confirmed prior to specification." Our client's purchaser looked into availability and said it's available for angles. I just wish he also supplied cost info.

@HgTX
I would try that but the client specifically stated A992 as the higher-strength option.

Does anybody know of a source for steel cost per pound by grade? Or would the cost vary depending on the shape? i.e. A992 W shapes would cost less per lb than A992 L shapes?

Thanks.

 

[HgTX]

Did the client consider A 572?

Hg

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[MatthewR]

I assume so. I gave him a list of grades to check on (incl. A572 and A992) and he replied back "angles are readily available in the A992".

HgTX, have you used A572 angles before?

 

[InDepth]

You can also check availability by shape and grade here:

http://www.aisc.org/steel/searchForm.aspx?id=2044

 

[HgTX]

I've used ASTM A 709 Gr. 50 angles, which are the same thing as A 572 Gr. 50. I would venture to say that just about every angle I have ever dealt with (since I'm a bridge person) has been ASTM A 709 Gr. 50.

What A 992 gets you that A 572 does not is an upper limit on the yield strength and on the yield-to-tensile ratio. Sometimes that's needed in design. Often it's not.

Your client's assessment that "A 992 is readily available in angles" is not as true as they think it is. The first angle mill I pulled up had A 36 and A 572 Gr. 50, but no A 992. If they're used to designing in A 36, and have A 992 presented to them because that's the new standard for W-sections, they may simply be unfamiliar with A 572.

Hg

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[MatthewR]

Hg, thank you for your response.

Would you happen to know how much more A 572 would cost than A 36? I know that's not something we're usually concerned with since we're engineers not construction companies. But I'm curious as to whether it's even worth the weight savings. I'm looking at no more than 10% savings in weight by going to 50 ksi steel.

 

[weab]

To be clear, A992 is cheaper that A36 for wide flange shapes.

 

[HgTX]

For mills that roll everything dual or triple certified, there's no cost premium at all. It really does vary. For plate, sometimes A 572 is more than A 36 and sometimes it is less. You'll have to check with a couple of mills. I'm not especially endorsing Nucor-Yamato, but they're the first one I thought of off the top of my head, and here's their angle pricing:

http://nucorbar.com/products.aspx?i=Angles

I'm not seeing any difference in price between the A 36 and A 572. Note that Nucor is a major producer and they don't list A 992 for angles.

Hg

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[MatthewR]

Thanks Hg - that's exactly what I needed.

Right before I checked back here, I spoke with a distributor in Texas that gets steel from Nucor and six others. He said that most angles are "dual grade" A36/A529 Gr. 50 and that there is no difference in price, and that's also what I see here.

Also, he said that eventually A529 Gr. 50 will be the standard grade for angles.

 

[HgTX]

I can't vouch for A 529 one way or the other. A 992 is based on A 572 with the additional yield/tensile restrictions. But I've seen A 529 listed in structural references, like this one:

http://www.aisc.org/bookstore/itemRedirector.aspx?id=12858

(article entitled "Are You Properly Specifying Materials?")

Hg

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