api5000We are a API 6A flange manufacturer,API 6A Type 6B 5000 psi(34.5 MPa) Weld Neck RTJ Flange,API 6 B 3000 psi WN RTJ Flange,API 6BX 10000 PSI Weld Neck Flange,API weld neck flangeAPI has specified weld necks for many 6BX flanges, and not done so for many others, but API has provided the basis for determining the dimensions of a 6BX integral flange that the manufacturer may attach to a