api5000API flanges standard is American petroleum institute. API 6a6b6bx flanges dimensions are desned to handle hher rated pressure. We are an API 6a flanges manufacturer. Visit now!API 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).