1.1 Purpose This International Standard specifies requirements and gives recommendations for the performance, dimensional and functional interchangeability, design, materials, testing, inspection, welding, marking, handling, storing, shipment, purchasing, repair and remanufacture of wellhead and christmas tree equipment for use in the petroleum and natural gas industries. This International Standard does not apply to field use, field testing or field repair of wellhead and christmas tree equipment. 1.2 Applicability This International Standard is applicable to the following specific equipment: a) wellhead equipment: - casing-head housings,- casing-head spools, - tubing-head spools,- cross-over spools, - multi-stage head housings and spools; b) connectors and fittings: - cross-over connectors,- tubing-head adapters, - top connectors, - tees and crosses, - fluid-sampling devices, - adapter and spacer spools; c) casing and tubing hangers: - mandrel hangers, - slip hangers; d) valves and chokes: - single valves, - multiple valves, - actuated valves, - valves prepared for actuators, - check valves, - chokes, - surface and underwater safety valves and actuators, - back-pressure valves;e) loose connectors [flanged, threaded, other end connectors (OEC), and welded]: - weld neck connectors, - blind connectors, - threaded connectors, - adapter and spacer connectors, - bullplugs, - valve-removal plugs; f) other equipment: - actuators, - clamp hubs, - pressure boundary penetrations, - ring gaskets, - running and testing tools (see Annex H), - wear bushings (see Annex H).