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RE: Butt-welding a gap

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The travel speed depends not only on the prequalified process specified, but
the amperage and the exact type of rod or wire.  The welder will have to
figure that one out as he performs the weld.  The travel speed on the root
weld will not be the same as the travel speed on subsequent passes.  A shop
will optimize the procedure based on what is most efficient for their
equipment.  They will often calculate total time in hours per foot of weld
and use the least.

There is a good comparison in the Lincoln Electric Procedure Handbook.  They
show the same weld using different interpasses, and then they calculate the
hours per foot of weld.  You can see the time for an individual pass varies
markedly from 5.5 in/minute to 14 in/minute for a weld using the same
process, same angle, same root, etc.  No, I would not even try to specify
the weld speed.  

The weld speed will have an effect on the temperature of the weldment, but
the only thing that needs to be specified is the MINIMUM preheat
temperature.  How they maintain that temperature is up to the welder.
Generally they augment the heat with a torch.  If it gets slightly hotter it
is OK.  If it gets colder then the minimum, you could have problems.  

Regards,
Harold O. Sprague

-----Original Message-----
From: Michael Bryson [mailto:mbryson(--nospam--at)NYASE.com] 
Sent: Friday, October 03, 2003 11:17 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Butt-welding a gap

How about also specifying travel speed for a field weld? Doesn't that
determine the req'd interpass temperature or is that just some assumed
value?

-----Original Message-----
From: Sprague, Harold O. [mailto:spragueho(--nospam--at)bv.com] 
Sent: Friday, October 03, 2003 6:30 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Butt-welding a gap

The only "butt joint" prequalified welds are limited to 3/8" thick base
metal for a one sided weld or 5/8" for a 2 sided weld.

The BU-4a-GF weld is unlimited on base metal thickness.  The one thing
that
you do not want to do is to let it cool.  You want to maintain an
elevated
temperature which is predicated on the base metal.  Engineers are often
not
given all of the information that they should be for weld submittals.  

I require submittals to specify pre-heat, interpass temperature, root
opening, groove angle, welding process, base metal thickness, and
shielding
(if required).  If it is in the field, I require them to shield the weld
from wind.  I generally require supplemental shielding on FCAW.  

I guess being a former iron worker, I remember how I screwed up more
than a
few welds.  

Regards,
Harold O. Sprague

-----Original Message-----
From: Michael Bryson [mailto:mbryson(--nospam--at)NYASE.com] 
Sent: Thursday, October 02, 2003 6:28 PM
To: seaint(--nospam--at)seaint.org
Subject: Butt-welding a gap

I am reviewing a welding procedure to "fill-in" a gap for a beam flange
moment connection. The gap is about 2" and it will filled in as a
butt-weld. They are claiming this is a pre-qualified weld (BU-4a-GF),
but I'm not sure that is correct.

I am wondering if some time should be allowed between passes to allow
the weld to cool? I can't find anything in the AWS for this.

(Note the connection is NOT for a seismic application.)

 TIA
 

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