B16.9 section 1.3 regarding fabricated fittings with circumferential welds are considered fabricated and not part of the scope of B16.9 therefore can't be marked with WP.
What is meant by circumferential welds is what I'm not sure about.
I am looking at a B366 Tee that the outlet is partially formed by the manufacturer and they have also welded a pup to complete the tee dimensional requirements. The main body of the tee is seamless. The weld has be radiographed. The MTR of the fitting only states the type, size and ASTM...