Question about GMAW procedure

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Let me set the scene... 6" Sch 10 pipe with a slip-on flange. Weld size called out is 3/16"  WPS restrictions says that we can use this procedure as a root pass on pipe and flanges. Also states that the fill and cap passes are only allowed on material that does not exceed 3/8", which the slip on flange easily does.Is this saying, if you have to put a root pass in that it will have to be ground out so that you can put the cap pass in with another procedure/filler metal? Can the root pass not be the cap pass? There is a decent gap between pipe and flange and wanted to make sure I can't mig it before I just use 7018 on all these parts.Thank you in advance Attached Images
Reply:It is not possible to remove a fillet weld on a SO flange (either one of them) from the back side.  Note 3 (third entry in WPS RESTRICTIONS) governs.  Note 2 would appear to apply to WN flanges or pipe butt welds, since that would allow the root to be removed from the back side.
Reply:It just says piping and then says "including" nozzle necks bla bla but does not say that it is limited to that, as long as it is piping. It doesn't specify WN flanges which a nozzle neck to a flange includes both WN and SO, doesn't it?.  It pretty much says to me that the only piping that it CAN'T be used on is branch connections, nozzle to shell welds or socket welds. That is how I intemperate it anyway.I'm not exactly sure what it means by stating that it can be used on other "applications" ...other than pipe maybe? like structure? So if that is true... as long as it is pipe, you don't have to remove the backside of the root ???The more I look at it, the less I know. LOL
Reply:I'm more than a bit perplexed by this WPS, as it's one of the most poorly written Section IX WPS's I've ever seen, and doesn't remotely address the required essential and nonessential variables.  Why they're limiting base metal thickness to 3/8" when any groove weld PQR picks up fillets on all thicknesses and diameters per Sec. IX is beyond me.  Unfortunately for you, the WPS contradicts itself in that it permits all fillets and welding without backing at the top, but then restricts you from performing root passes on welds with backing (including fillets) on the bottom.  Because of the hosed up notes, were I reviewing this WPS in the field, I would say that you are not authorized to make GMAW root passes for SOF fillet welds on pipe spools on the basis that note 2 is not specific to groove welded connections, UNLESS your connection is considered to be a nozzle neck.  Then again, I live in the nuclear world where we're bound by verbatim compliance.  In reality, the only thing that should preclude the use of GMAW for fillet welds qualified with a groove PQR in Section IX space would be a client requirement, even if it's short arc.