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RE: Calling out/specifying tubes

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Charlie,

I agree with you.  HSS is the proper designation. 

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.  Problem areas:
1.	The A618 was written as a weathering steel spec.  The tube guys
can't guarantee the minimum % copper listed in A618 because of the plate
suppliers today.  It is weird in that the Type I is not supposed to be
weathering, but it requires a minimum of 0.20 copper.
2.	The A618 is hot formed and welded.  The tube manufacturers cold form
the plate prior to electric resistance welding.  A618 does not care how they
are welded.
3.	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.
4.	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.

Our engineers were led to their HSS material selection by verbiage in the
LRFD Manual.  I am the Diogenes (skeptic) of structural engineers, and I
like to call the suppliers to find out availability.

My frustration is that this information is from the only HSS suppliers that
have the ability to produce the HSS that we were going to specify for a high
seismic project.  We finally switched to all wide flange braces.

With our high seismic job we selected 50 grade wide flange A992.  No
problem.  To connect it we were going to use A490 bolts and selected Gr 50
plates and found A490 bolts and A572 Gr 50 plate stock was no problem.  

To reinforce the connections and we also wanted to use angles in a Gr 50
material perhaps A572.  We also tried to find A572 Gr 50 channels, and that
is where the wheels came off.  We decided to not confuse the issue and went
to A36 for all connection plates, angles, and channels.  How available is
angle and channel stock in a Gr 50 material?

The point is that just because it is in the AISC manual does not mean it is
available.  Not difficult to obtain but impossible to obtain unless your
talking about a thousand ton order from Korea.

Regards,
Harold Sprague


> -----Original Message-----
> From:	Charlie Carter [SMTP:carter(--nospam--at)aiscmail.com]
> Sent:	Friday, June 02, 2000 8:47 AM
> To:	'seaint(--nospam--at)seaint.org'
> Subject:	RE: Calling out/specifying tubes
> 
> > For square and rectangular tubes, is it now recommended that they be 
> > specified as HSS or can TS still be used? 
> 
> HSS is the proper designator for round and rectangular products produced
> to ASTM A500, A501, A618 and A847. It stands for hollow structural
> section. Note that these designators do not apply to steel pipe (ASTM
> A53). For more information on all of this, go to part 1 of the three-part
> materials feature here:
> 
>     <http://www.engr.psu.edu/ae/steelstuff/matls.htm> 
> 
> The shift from TS to HSS was introduced by the Steel Tube Institute (yes,
> I see the irony in their name) about five years ago and is still filtering
> its way through the various publications and references that exist.
> 
> Charlie 
>