Long Weld Neck Standard
Class 1500 Long Weld Neck Flanges
MSS SP-97 long weld neck flanges for Class 1500 service
Class 1500 Long Weld Neck flanges are engineered for extreme-pressure vessel nozzles in the most demanding process environments. The forging size, material quality, and machining precision required at Class 1500 make these among the most specialized flange products manufactured.
At this pressure class, the hub wall thickness approaches or exceeds the vessel shell thickness, and the forging must maintain uniform grain structure throughout to ensure consistent mechanical properties. Ultrasonic examination per ASME SA-388 is standard, with acceptance criteria per ASME SA-578 Level C or more stringent.
These flanges are found on high-pressure reactor vessels, synthesis converters, and ultra-high-pressure heat exchangers. The available size range at Class 1500 is typically NPS 1/2 through NPS 24, with larger sizes available as special orders requiring custom forging dies.
