I have a WPS that requires SMAW for the root and hot pass and the rest of passes to be done using FCAW.
SMAW max thickness : 0.25" and FCAW max : 0.75"

PQR : 0.125" SMAW and 0.625" using FCAW

QW 401 requires requalification if a welding process is changed. (essential variable)

Can I eliminate the FCAW process and use SMAW only for all passes on a 0.75" thick pipe section?.

My interpretation is that this would not be allowed since the WPS limits the SMAW process to 0.25" max deposited weld metal thickness and requalification would be required to use one weld process. I couldn't find a clear cut interpretation about elimination of one welding process.

I'd appreciate any feed back.

In my opinion you're interpretation is correct.

You could eliminate one or the other of the processes but would still be bound by all other variables which in this case the thickness would negate depositing over 0.25 inch of weld metal using the SMAW process.

Further, if you wanted to eliminate the SMAW process for example, you would only be able to deposit the FCAW in a joint with backing. Make sense?

Yes, You can.
mauro

Thanks for the responses, I'm leaning on requesting requalification, I'll give some feed back when i speak to the metallurgist on monday.