Repair of caustic stress corrosion cracking on non-PWHT tank

[chok7]

Hi all,

General questions around repairs of caustic stress corrosion cracking in carbon steel storage tanks that have not been PWHT and see high-med strength cleaning caustic at approx 90 deg C.
For context, fairly substantial CSCC is already present along most HAZ zones (transverse cracking) and along welds of fillet welded internal attachments. All repairs are short term temporary solutions at this stage as it is no longer economical to PWHT any repairs.

Does anyone have experience for:

1. Any slightly greater success with repairs holding up using low strength GP electrodes as opposed to low hydrogen electrodes? Would any electrodes perform slightly better in areas where CSCC is already present?
2. Experience with using multi-pass small runs vs large single pass beads for grinded out weld repairs in HAZ areas affected by CSCC?
3. Experiences with using metal spraying or coatings in these high temp/strength caustic environments as temporary repairs?

Thanks

 

[Dhurjati Sen]

How severe are those cracks?
Was there any leakage / failure?
Do you have stand-by tank?
Is this the main storage tank or a day tank?

 

[Trestala]

1. Any slightly greater success with repairs holding up using low strength GP electrodes as opposed to low hydrogen electrodes? Would any electrodes perform slightly better in areas where CSCC is already present?
2. Experience with using multi-pass small runs vs large single pass beads for grinded out weld repairs in HAZ areas affected by CSCC?

Have you looked into NACE SP0403? Those approach to welding will still not sufficiently reduce the residual stresses. Even temper bead welding is not effective per NACE SP0403.

3. Experiences with using metal spraying or coatings in these high temp/strength caustic environments as temporary repairs?

You can consult with providers similar to: https://integratedglobal.com/industries/caustic-vessels/

 

[chok7]

Have you looked into NACE SP0403? Those approach to welding will still not sufficiently reduce the residual stresses. Even temper bead welding is not effective per NACE SP0403.


You can consult with providers similar to: https://integratedglobal.com/industries/caustic-vessels/

Thanks Trestala, I've done some rough research into this but have now come to the conclusion that there is no real advantage between weld processes once CSCC has initiated.

I will check out IGS's products, thanks.