Q. Flanged pressure vessel nozzles?

The Designer is responsible for ensuring that the facings, bolt circle, number of bolts, and size of bolts of vessel nozzles, match the mating piping flanges. Flanges for all flanged pressure vessel nozzles, equal to or smaller than NPS 24, shall meet the requirements of ASME/ANSI.

These are standard carbon, low alloy and austenitic stainless steel flanges of the integral hub, welding neck style, that are dimensionally the same as MSS SP-44 flanges. The materials covered are identical with those in Materials Group 1 and 2 of ASME/ANSI B16.5. Line valves and machinery nozzles may be provided with flanges of MSS SP-44 dimensions. Therefore, vessel nozzle flanges, meeting the dimensions of Series A flanges, may either be necessary or desirable. Series A and Series B flanges are not dimensionally compatible in all sizes.