What category of weld is a nozzle to shell weld?

What category of weld is a nozzle to shell weld?

• A. Category D
• B. Category A
• C. Category C
• D. Category B

Answer: (A)

Category D is used for nozzle-to-shell welds because these joints are among the most demanding in a pressure vessel. The connection where a nozzle meets the shell creates complex geometry and high stress concentrations, which raise the risk of leakage or failure if the weld isn’t done and inspected to rigorous standards. Labeling this joint as Category D signals stricter fabrication controls and more stringent inspection or qualification requirements than for other, less critical weld locations. Other categories apply to simpler or less stressed joints, so they don’t demand the same level of scrutiny.

Category D is used for nozzle-to-shell welds because these joints are among the most demanding in a pressure vessel. The connection where a nozzle meets the shell creates complex geometry and high stress concentrations, which raise the risk of leakage or failure if the weld isn’t done and inspected to rigorous standards. Labeling this joint as Category D signals stricter fabrication controls and more stringent inspection or qualification requirements than for other, less critical weld locations. Other categories apply to simpler or less stressed joints, so they don’t demand the same level of scrutiny.