Welding Neck flanges, available in all pressure ratings and sizes, are butt-welded to the end of the machined with a .25" (6.4 mm) raised face, in addition to the designated flange thickness. ASME/ANSI B16.5, titled “Steel Pipe Flanges and.
ANSI B16.5 Class 150 Flanges. Nom. Pipe. Size. O. T1. R. X. No.2/Dia. of Holes .. OD. RF. Bolt. Circle. #. Holes. Dia. Holes. Weld. Neck. Blind. Nom. Pipe. Size. O. C .. CLASS 300 (R.F.). NPS. B. E. A. C. D. G. T. A. C. D. G. T. 1/2”. 21. 25. 45.