Some people may think there would be a problem with sediment in the extra gap space inside the socket created because of the weld bevel on the butt-weld reducer.
But, if you have a commodity that has sediment problems then you would not be using socket-weld fittings.
I'd say that it depends which end you insert into the fitting. Inserting the 2" end into a 2" SW fitting would result in a small gap where the fillet would need to be deposited, but probably no big issue. Inserting the 1" end would probably not permit proper engagement of the part into the socket, since the BW reducer has very little straight length at the 1" end.
They do make swage nipples for this purpose, though they are a lot harder to get your hands on than BW reducers are. Locally the true article is seldom stocked, and required swage nipples are usually hogged from solid barstock- a tremendous waste if you ask me.
Terrible "workmanship", but not specifically rejectable per B31.1, B31.3, ASME VIII, etc. I reject this kind of thing under "workmanship", and tell the fabricator to get specific permission from the Engineer, since this is not how these fittings were designed to be used. Never had an Engineer dumb enough to 'sign off' on this.
However, pennpiper is correct. Does not degrade the strength of the system.
If the end inserted is the small end of the reducer then the welder is going to weld into a corner (angle of access less than 90). It seems like that might impact penetration into root.
If the end inserted is the large end it seems like they'll be bridging a bigger gap at the root and you might have a smaller weld throat than you'd otherwise expect if you were defining weld size just by legs on the fillet.
This way of welding ASME B16.9 fitting is absolutely PROHIBITED!
Please recall that B16.9 fitting is a butt-welding element by its definition. This standard provides a fixed position for the welding ends (with reference to either centerlines of the fitting or the overall dimensions).
Design and use of B16.9 fitting is permitted only according to its proof test (B16.9 2.2).
Since a proof test assembly (B16.9 9.2) is made by welding of pipe section to each end of the fitting, the meaning is that the only way to connect a B16.9 fitting is a butt weld.
Any operation involved in any section of the fitting other that of welding ends is prohibited and throws it into "Unlisted Component" acc. to its significant (ASME B31.1 / B31.3 / B31.8 / VIII-1 etc.)
