api5000API 5000, 10000 are used in reference to wellhead 'christmas tree' pressure ratings as well used for the wing valve, master valve ratings. There may be hher classes asRev. 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 45