ASME B16.47 Series B flanges are compact, large-diameter weld neck and blind flanges from NPS 26" to NPS 60", in Class 75, 150, 300, 400, 600 and 900. Their dimensions come from the former API 605 standard: smaller outside diameters and more, smaller bolts than Series A, which keeps weight and space down on refinery and process piping and on equipment nozzles.
Raaj Fittings manufactures B16.47 Series B flanges in carbon, low-temperature and alloy steel, stainless steel and duplex at our two plants in India, for refinery, petrochemical and EPC projects across the Middle East, Europe and the Americas.
For the same size and class, a Series B flange has a smaller outside diameter, a smaller bolt circle and more bolts of smaller diameter than a Series A flange. The two series cannot be bolted together. When replacing a large flange, check the bolt count and bolt-circle diameter against the drawing to confirm which series is fitted.
Pressure–temperature ratings follow the ASME material groups, as for B16.5 flanges. Raised face is the usual facing; ring type joint grooves can be machined to order. Weld neck flanges are bored to the pipe wall and bevelled to ASME B16.25. Materials include ASTM A105, A350 LF2, A182 chrome-moly, stainless and duplex grades.
Every B16.47 Series B flange is made from PMI-verified material, dimensionally inspected against the ordered standard and marked with material, size, rating and heat number. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.
API 605 was withdrawn when its dimensions were incorporated into ASME B16.47 as Series B. Drawings that call for API 605 flanges are met by B16.47 Series B.
Series B uses a smaller outside diameter and bolt circle with more, smaller bolts, so less forging material is needed for the same size and class.
Yes, Class 75 is available only in Series B, for low-pressure large-diameter service.
Compare the outside diameter, bolt circle and number of bolts with the B16.47 tables. For the same size and class, Series B has a smaller diameter and more bolts.