CA6NM Pump Case Weld Repair 1

[BurningFuel]

I have a issue with a CA6NM slurry case, With a complete pmi the results show 300 s.s., Inco 82 and other unknown materials in the wetted areas, The case has boron coating, Wet mag shows well the major cracks are visible but there are small spider web cracks and with grinding go over 1/2" deep case is 1" and better thick, My problem is how to repair these cracks with 410NIMO, Stress relieve, and fully boron coat the wetted areas at 1900*, It was steam cleaned at 185* and we heard two very clear sharp TINGS! Is the case worth saving going in and butchering out the volute, removing entire reg. fits, gasket faces, installing new CA6NM split waters, welding in new reg. fits using 410NIMO? And another question should the back side of the cutwaters be perfect how much work really needs to go into them rough grind, smooth grounded surface does it matter?

 

[metengr]

The presence of other materials in the CA 6NM pump case concern me, and are present because of previous weld repairs.

If are to do this repair correctly, I would remove the filler metal from the previous weld repairs because I would bet these locations surrounding the repaired regions probably contain cracks.

I would really take a hard look at deciding if the case should be replaced or weld repaired. If weld repair is the cheaper option, you need to use 410NiMo filler metal in all weld repair regions.
This means preheat at 500 deg F, weld repair, cool to below 200 deg F and PWHT at least twice, with the second PWHT 50 deg F below the first PWHT. You may have serious distortion problems, which goes back to replacing versus weld repair.

 

[BurningFuel]

The Case is now back in service, We thank you guys very much! We cut all reg. fits .200" deeper to insure good case material welded with smaw 410 nimo few hundred pounds worth! And it survived boron coating!

Now we have another question, In our attempt to save man hours in the future we bought a bug O system, to be used with GMAW process, We have procedures but it is not working out like we thought on test pcs. We are and have used .035 410 NIMO solid wire with Ar98% 2%ox, and Tri Mix gasses, We have tried spray arc, and short arc process and both are showing surface cracks in the weld, The welds look great until you actually start looking at the grain and you can see small cracks. Now we did you use short arc 410 nimo .035 wire to fill in the bolt holes on the case using tri mix gas and there were no cracks we had the case wet maged a few times, So we are not understanding this new old process? Any help would be great

 

[cloa]

Better to post a new thread in the Welding Forum.

http://www.eng-tips.com/threadminder.cfm?pid=725

 

[EdStainless]

Use straight high purity Ar for this material, NO oxygen.

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Plymouth Tube

 

[stanweld]

You may also wish to try 98% Ar - 2% CO2 mix with the spray arc transfer mode or use welding grade Ar as EdStainless recommended.