F43 application 1

[VeryPicky]

Hi

Can anybody advise me on possible applications for the F43 filler on ASME boiler and B31.1/B31.3 applications;

- SA-213-TP304H to SA 213-T22
- SA-213-TP347H to SA 213-T22
- SA-213-TP321 to SA 213-T11
- SA-213-TP321-H to SA 213-T22
- Tube to Tubesheet weld. SA-213-T22 (tube) to overlay Inconel (Tubesheet)
- P8 attachment welded to carbon and low-alloy tubes.
(problems with failures of the welds tearing into the tube instead of failing on the attachment side.)

If other filler is recommended what are the possible advantages?

 

[metengr]

jacekscan;
For our Power boilers, we routinely specify the use of Inconel (F 43) filler metals for joining dissimilar boiler tubes exposed to elevated temperature service. Inconel 82/182 are the "workhorse" filler metals for us. There are several advantages;

1. the Inconel filler metals have a linear coefficient of thermal expansion that falls in between the austenitic grades (304, 347, 321) and the ferritic grades of boiler tubes (T11, T22). This reduces the thermal stress affects along the fusion zones of the dissimilar metal weld in service.

2. the second advantage is that the Ni base alloy seems to reduce or slow down the rate of carbon diffusion along the ferritic side of the weld joint, thus extending the creep life of the dissimilar metal weld joint.

3. the Inconel filler metal is very ductile, thus absorbing weld metal shrinkage stresses - less residual stress in the weld joint.

 

[VeryPicky]

Metengr
Thanks for your response. You are raising very important points there.

How do the 309L/309MoL fillers behave in that application?

 

[metengr]

The 309 filler metals are ok for service temperatures BELOW 800 deg F. Above this temperature, you have increased risk of carbon migration resulting in local creep damage along the fusion zone of the dissimilar metal weld (on the ferritic tube side).

Also, I did not mention the benefit of "buttering" with the Inconel weld metal on certain ferritic base metals to avoid post weld heat treatment of the completed weld joint.