... Sealing Ring Gasket (wellhead equipment) API 6A gasket rings is widely used in petroleum, wellhead products,gate valve,flange,etc. ... StandardApplicationshapeAPI 6A,ISO 90012000,ISO9001 2008,ANSI etccasing head,flange ... as below:1) Wellheads (casing/tubing head, crosses ,flange adapter,etc)2) Valve (FC/FLS gate valve, mud ...