Dear Experts,
I have try to qualified repair procedure 14'inch superduplex pipe 30 mm thickness(UNS32750) where using purging and shielding gas 98% Ar and 2% N2.Unfortunately I failed on the pitting corrosion testing(35⁰C)5g/m2 weigh loss(test required 4g/m2)G48 method A. Original weld pass at 0gram weigh loss. Piting was found at side(near excavation area) and root weld where the side of test piece is more severe . Heat input for root around 1.2KJ/mm and the rest passes are 0.8-1.1kjmm. Filler wire used is ER2594.
a)Can you guys provide information for the purging usually used( I am using only span), suitable environment for welding superduplex?
b)Do we need to cut off the tip of the filler wire if it is oxidized(reused wire)?
c) Can we use power brush for interpass cleaningexclude capping?
d.) The deposite thickness is thin for every pass in order to get high travel speed/low heat input?
e) I am using cleaning agent acetone to clean the bevel , does this matter?
Please let me know if any goes wrong.
Weld details
1.) Single V joint
2.) Sample extract from to position. Welded 6G position.
3.) Repair procedure. Excavation up to 6mm root ligament where as per drawing.
4.) 
5.) Pitting corrosion picture
6.) Interpass temperature <100⁰C
7.) Oxygen level <50ppm, excavation method grinding.
8.) Interpass cleaning, power brush.
9.) 
10.) 
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