... assembled of gauge bull plug, tree cap,threaded nipple,top connetctor,valves,cross and spoolNB:2-9/16" 3-1/16 ... domestic and overseas oil fields, it consists of casing head, casing spool,tubing spool,tubing head adapter,studded cross, threaded flanges,adapter ... spool,gate valve,choke valve and the tree cap. All wellhead tree ...