api 5000API Specification 6A covers wellhead and tree equipment as follows: API Specification 6A Wellhead Equipment Valves, Chokes, and Actuators Plugs, Connectors, and Gaskets Other5000# API Socket Weld Flange is made up of A105 carbon steel and has a minimum yield strength of 45000. API 10000 Flange is manufactured from hh steel alloy after heat treatment