Which one will last longer??

[bmoorthy]

A 25 mm thick Carbon steel shell (1m long) is to be welded with (Longitudinal seam). Butt welded butt Joint.

The joint is going to be radiographed and also ultrasonically tested. (ASME Sec VIII Div 1 UW 51 and Appendix 12 acceptance criteria respectively).

The material is subjected to Low temperature (MDMT -46 Deg C)

Supposing 6 identical shells are being welded simultaneously (Same configuration) but using different welding processes

1)SMAW
2)GTAW
3)SAW
4)GMAW
5)FCAW
6)PAW

supposing
extension from each shell is available for destructive testing and
no rework was done and all the six shells goes to NDT simultaneously
Whether to chip back and weld or not is left to foreman (Highly experienced)
Weld Joint fit up of all the 6 joints were good
The welders who welded has equal skill competence
And Supposing all the 6 shells are put into use for 50years in H2S service,



A) Which will have lowest HAZ
B) Heat Input on which process would have been more
C) which would have taken less time to complete from start to finish (From Plate to NDT clearance)
D) Which process would have the heighest Impact Properties and which would have the lowest impact properties
E) Which process would have resulted in heightest hardness and which one the lowest hardness
F) All things remaing the same which would have costed less
G) Which one will most likely go for repair after NDE
H) Which process would have demanded least use of Grinding process

I) which one will most likely fail first in service and which one might out last the other?

 

[metengr]

(a) HAZ hardness is primarily dependent on base metal composition and preheat requirements. On the other hand, the size of the HAZ is directly related to welding process heat input.

(b) In general; for heat input SAW>(FCAW ~= GMAW)> GTAW > PAW

(c)higher deposition rate processes (SAW, FCAW, GMAW) > GTAW, PAW

(d)impact properties are directly related to weld metal composition and to some extent heat input from the welding process. Impact properties in descending order GTAW>FCAW>SAW

(e) Weld metal composition and base metal composition affect hardness for equal cooling rates.

(f), (g), (h) depends on the day of the week for the welders

(i) if I could predict this, I would be self employed and probably be independently wealthy.

 

[dbooker630]

'D' can also depend on shielding gas used. In some cases we use 100%CO2 vs. Ar-O2 mixes to increase penetration with FCAW. That is when we're not using self-shielded wire.