api5000Rev. 4. 0 2018. 07. 27 FLANGES - 87 API 6A FLANGES Size OD C E1 G K T J1 J4 R BC N H Ring Number BX 13 58˝ 675 6 14.3 408.00 457 112.8 481.0 23.9 16 590.60 16 45API 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