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RE: Weld Fractures (refrain)

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Normally A53 B pipe is thought of as low carbon requiring no preheat for up
to 3/4" thickness.  But A53 B pipe can push the carbon equivalents if the
manganese and chromium contents are on the high side.  A53 B pipe has a
carbon content of 0.30 and a maximum Ceq of 0.70.  The 0.70 carbon
equivalent generally requires a preheat from 400 to 700 degrees F, but
proper welding procedure can mitigate the need for preheat.  The problem is
probably due to the welder using a low current.  The 1/8" rod requires less
amperage to melt, but it may not provide sufficient heat for fusion.  The
3/16" rod will require more amperage to melt, and should produce sufficient
heat for fusion even if the welder is in the training wheel stage.

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	Robert Rollo [SMTP:rrollo(--nospam--at)TEAM-PSC.com]
> Sent:	Wednesday, December 20, 2000 9:53 AM
> To:	'seaint(--nospam--at)seaint.org'
> Subject:	Weld Fractures (refrain)
> 
> welding procedure was single pass SMAW with (and i misspoke previously)
> 1/8" 5P+ 6010 rod, again no preheat.  wrong rod looks like to me and can
> you get 3/16" fillet from 1/8" rod in single pass ?
> 
> the rod supplier advised changing to the 3/16" 7018. 
> 
> cracks appeared after final cooling at the outboard toe of the weld (more
> like separation of fillet from base material pipe) . . . odder still ,
> they now tell me that they alternated sides as they stitched and yet only
> one side is separating . . .
> 
> welder is not certified and did not report amperage, etc. 
> 
> sound like i have the wrong welder doing my work ? 
> 
> thanks again for the brain time ! 
> 
> r o b e r t   d.   r o l l o
> 
> Parkhill, Smith & Cooper, Inc.
> 
> 4222 85th st
> 
> Lubbock, Texas 79423
> 
> (806) 473-2200 vox
> 
> (806) 473-3500 fax
> 
> rrollo(--nospam--at)team-psc.com
> 
> rdrollo(--nospam--at)aol.com
> 
> 
> -----Original Message----- 
> From:   Davis Parsons [SMTP:davisp2(--nospam--at)flash.net] 
> Sent:   Tuesday, December 19, 2000 6:29 PM 
> To:     seaint(--nospam--at)seaint.org 
> Subject:        Re: Weld Fractures 
> 
> 
> 
> Robert Rollo wrote: 
> 
> > 
> > 
> > scenario: 
> > 
> > C 3x4.1 (A325) flange tips welded vertically to the side of a 12" Sch 
> > 40 (A53B) pipe for sign blade attachment. 
> > 
> > channel is tacked in position then we are stagger stitching with 3/16 
> > fillets 2" @ 6". 
> > 
> 
> What welding procedure was used? 
> 
> > 
> > outside temp was about 35F.  weld rod was 3/16" 7018.  welder attached 
> > one flange all the way down as indicated.  when attaching the second 
> > flange (opp side), the welds are cracking away from base material 
> > (pipe) upon cooling. No applied loads. 
> > 
> 
> Which weld cracked? The first weld pass or the second? 
> 
> > 
> > Thoughts ?  Other than alternating sides as installation proceeds ? 
> > Are we dealing with radial exp/contraction of the pipe ?  i would have 
> > thought channel web would flex enough to accomodate it . . . 
> > 
> > tia 
>