RE: TIG welding of Large dia SS Pipe

this is fine Geoff. But please note the the lenght of those bladder are quite long for large bore piping (SOCAP from Italy). Beside u stiil have to find a way to insert the hose near the weld area pass the ballon.

We've acutally tried quite a number of technique. We built a cage, inserted the welder to perfrom back weld , then from the outside we ground/clean the root then do the hot pass. If we're really in hurry, we put two welders - one inside and one from the outside. Weld are perform almost simultaneouely with the welders from the inside slightly ahead. The 3rd method is to install the hat or dam fabricated out of carboard and fitted from the inside around te weld joint. we then tape a masking on the outside and perform the weld. The last is the use of dissolving paper to create a dam around the pipe.
The first 2 tecnique actually eliminated the need for backing gas.- its the oxiadation that you worry about with this type of welding.
> ----------
> From:
> geoff.stone@lendlease.com.au[SMTP:geoff.stone@lendlease.com.au]
> Reply To: <a href="/group/PipingDesign/post?postID=WVnW17YlhW3ee7V7UGChcIG6Wcr-FX8Sy6g9iHSJeFUbs0ODbeg8cvJLl5DEvH0aDvW9BB7NwrzUFDcr0fMByrUleA">PipingDesign@yahoogroups.com</a>
> Sent: 28 June, 2001 1:57 AM
> To: <a href="/group/PipingDesign/post?postID=WVnW17YlhW3ee7V7UGChcIG6Wcr-FX8Sy6g9iHSJeFUbs0ODbeg8cvJLl5DEvH0aDvW9BB7NwrzUFDcr0fMByrUleA">PipingDesign@yahoogroups.com</a>
> Subject: Re: [PipingDesign] TIG welding of Large dia SS Pipe
>
>
>
> USe inflattable bags to reduce the volume being purged.
>
>
>
>
> "SARE, RALPH H." <SARERH@YANPET.SABIC.com> on 27/06/2001 21:15:39
>
> Please respond to <a href="/group/PipingDesign/post?postID=WVnW17YlhW3ee7V7UGChcIG6Wcr-FX8Sy6g9iHSJeFUbs0ODbeg8cvJLl5DEvH0aDvW9BB7NwrzUFDcr0fMByrUleA">PipingDesign@yahoogroups.com</a>
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> To: "'PipingDesign@yahoogroups.com'" <PipingDesign@yahoogroups.com>
> cc:
>
> Subject: [PipingDesign] TIG welding of Large dia SS Pipe
>
>
> Case Statement:
> 24" NPS sch10S 304L, "Z" configuration broken into two shop fabircated "L"
> shape spool. One field weld to join the two broken "L" piece. Each L shape
> contain one flange, one elbow and one lenght of piping. Butt weld, 37.5
> deg
> bevel. Typical to 4. Vertical position (long side)
>
> Problem Statement.
> Welding calls for TIG process with argon purging. no metal backing. How
> can
> i reduce the cost of argon purging
>
>
>
>
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Received on Thu Jun 28 06:55:00 2001