Channel 12X 20.7 tolerances

Date 06-09-2009 16:45

Greetings

I have some pieces of C 12 X 20.7 they are warped from when the mill stamped the material ID into them.

So across the width of this channel their is a hump at about 6 inches down from either end and runs the whole length of the stringer. so the web is not flat! Where is the best place to find tolerance info for me to reject these Channels? I looked in ASTM Standard but did not find anything related to flatness of channel webs????????????????

By bmaas1

Date 06-09-2009 17:24

Does A6 reference this issue?

Brian

By david bean (**)

Date 06-09-2009 18:56

I havent found anything so far, nothing that show a tolerance for flatness in the web. But im not going to give up quite yet!

By G.S.Crisi (****)

Date 06-09-2009 19:10

Look at a Bethleem Steel or United States Steel catalog. They show the tolerances for rolled shapes.
Giovanni S. Crisi
Sao Paulo - Brazil

By swnorris (****)

Date 06-10-2009 17:28

If ASTM references it, it would be in A6. It really doesn't sound like this one needs a reference. Just reject it and have the supplier replace it.

By DAYANARA (**)

Date 06-11-2009 01:03

Dear David
ASTM A6 or AISC have tolerance for mill material, if you will not found you remember only can reject these Channels the Enginner or Designer accordace requierements.

By welderbrent (*****)

Date 06-11-2009 01:04

David,

AISC Steel Construction Manual in section 1-9 under Standard Mill Practices and 1-119 under ASTM A6 Tolerances goes through many variables for channels. The web flatness is not one of them.

But, I cannot say that I have ever had a piece of standard channel over 6" that if you put a straight edge across the back would be "flat". The straight edge will very seldom touch at the corners. Jr channel will touch the corners but not the middle. Misc channel is usually flat, it is much heavier than standard channel.

I don't know that it is actually from the mill stamp. I believe you will find they are just made that way. But you are within your rights to question your supplier and find out. Make him research the tolerances and provide you with proof that it is good.

Oh, How much are we talking about? With a straight edge across the back, do you have 1/16" under the straight edge at each corner? 1/8"? Just curious.

Have a Great Day, Brent

By david bean (**)

Date 06-25-2009 16:58

It was 3/16 high in the middle! I have since rejected this and sent it back to the supplier.
thanks for the feedback>>

Regards
David J. Bean