1) API 6A Spec 2) Christmas tree is an important piece of equipment used to control fluid ... type is slip type, weld type, and thread type. Christmas tree is an important piece of equipment used to control fluid ... PR1, PR2, under API SPEC 6A.The bore of Christmas tree ranges from 7-1/16 to 21-1/4, the ... being PR1, PR2, under API SPEC 6A. wellhead and christmas tree