As you are quoting QW-462.5, I take it you are using ASME? If you read QW-462.5(b+c), in the general notes, it states 'overlay may be on outside or inside of pipe', I am not saying this answers your question as I get the feeling that there exists some uncertainty in your company's planning. QW-380/1 may help.
Hi Reuben,
This reply maybe a bit out of date as I have just joined the forum.
We have for years (since 1993) qualified cladding PQRs on the OD of a pipe (DNV, ABS, ISO and Lloyd's approved) with no problem for them being accepted for ID, OD or Ring Joint overlays.
We use hot wire pulsed GTAW for all of our overlays welded in the 2G rotated position, ASME (Always, Sometimes, Maybe, Except for) is not too prescriptive for weld overlays and leaves a lot of grey areas, we have standard cladding rig booms and constant rotation head CNC controlled rigs too.
Thing to remember about CRA overlay is the thickness qualified on the test coupon you use and the separate variables table.
Don' t see why there is a hardness issue with boring out your solid bar to leave 25mm (1") wall thickness, with 4130 the ruling section of hardness penetration is normally taken as being 38mm (1-1/2") so the core of your solid bar is going to be softer than the OD.
I have plenty of qualified Alloy 625 overlay on AISI 4130 that I am willing to share, if you want PM me.
visit our web site www.ajt-engineering.co.uk and look for the welding tab