api 5000API 5K API 5K means an API-defined BOP confuration with a rated working pressure of 5,000 psi and as described in API RP 53, adopted by reference at 20 AAC 25.527(c). Source: AlaskaRefer API 6a 6b And 6bx Flanges Weht Chart According to ASME B16.5 And (American Petroleum Institute) API 6A 5000 Flange Dimensions. Api 6a Flange Material Specification.