Steve
I hope that the ladies may not have replied to your
post. They do not seem to have Titanium Weld
experience.
Coming back to the actual problem and expected few
additional tips of caution, I suggest that you make
sure that the pipe at the point where you wish to add
flage piece has to be thoroughly checkeed using insitu
metallography. You have to take out a ring piece ,
section it and them take micrographs on both external
and internal surfaces. If there is no sign of stress
corrosion cracks, you are assured of a good weld
without problem. Any way you may be using GTAW (TIG)
wilding with lot of Argon as shielding at the weld and
nearby zone.
We did this in a Soda ash plant where in a critical
area we had Titanium Piping and heat exchanger and
repairs were required after a service exposures of
around 4 years.
Good Luck
Narendra K Roy
narendra_roy@yahoo.com
www.charismaglobal.com
>
> Ladies and others
>
> I have some existing 100NB GR12 Ti pipe that I want
> to add a flange
> pair to. The pipe spool consists of
> flange-straight-bend-straight-
> bend-straight-flange; one piece. I want to add a
> flange pair to the
> middle straight in order to simplify descaling;
> currently using
> 30,000 psi water blaster. By adding the flange pair,
> we will have
> good access to each straight portion, and can use a
> lance instead of
> a rat.
> The pipe has been in service for 4 years; no
> apparent corrosion. The
> process fluid is a metallurgical slurry with dilute
> sulphuric acid in
> the carrier liquid.
> However I have not welded new flanges to old pipe
> before (only new to
> new).
> I envisage a thorough clean/linish/pickle (to remove
> iron traces) ,
> thickness check, dye check and then prep, weld, NDT
> and hydro as for
> new pipe using prequalified procedures and
> experienced qualified
> welding operators.
>
>
> However given the brittleness of Ti,the criticality
> of this spool
> (not a good one to fail), and the uncertainty of
> NDT, I wondered if
> anyone has any experience or advice on welding old
> Ti to new Ti.
>
> Especially interested to know if any other pre-weld
> conditioning of
> the old pipe is recommended.
>
> Cheers
>
> Steve
>
>
>
>
>
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