[MW:11039] Dissimilar Weld between Inconel 602 CA to P4

Dear all

 

We have a dissimilar weld between equipment nozzle ( Inconel 602CA ) to connecting pipe A335 P11 (P4) .

 

And the Vendor WPS States that to do  Buttering by SAW in P4 with Inconel 625 ( ERNiCrMo-3 ) with a min thickness 10mm in the bevel area  and butt welding by Inconel 625 ( GTAW + SMAW )

 

Now lets come to only buttering , In our project we have 2 Joints , so to do buttering in a bevel area we had a made set up as attached 

 

This set up is only to make buttering in bevel area , once the welding will be finished the centre portion will be cut and machined .

 

We finished the welding

 

But after SAW Welding we found so many Weld Metal Shrinkage all over the weld mostly at centre of the weld .

 

I need to know what would be reason for such kind of defects , is it 45 mm of Root gap made ?

 

 

Care had been taken 

 

1. Welder been seperately  qualified for this process . And Welder Test are satisfactory with no defect .

2. Amp and Volts as said in WPS

3. Preheating & Interpass temp been maintained as said in WPS

4. Correct usage of tools and tackles .

 

 

Thanx and Regards 

A.P.Abraham