Scope of application: Steel gate valves, globe valves, and check valves with a nominal size of NPS 4 or less used in the petroleum and natural gas industry. This standard covers small steel gate valves with flange connections, threaded connections, socket weld connections, and butt weld connections at the ends, including valve body extension types corresponding to the following standard specifications of pipelines in ASME B36.10M or ASME B36.19M: a) flange weld ends and butt weld ends for NPS 4 and smaller specifications, b) threaded connection ends and socket weld ends for NPS 2 1/2 and smaller specifications, and c) corrugated pipe seal valve cover types for NPS 2 and smaller specifications.

2、 This standard also specifically includes the following types of valves:; a. Class 800 valve, with threaded connection, socket weld connection or butt weld connection at the end; Internal screw with lifting rod (ISRS) and threaded packing sealing nut, or external screw and bracket with lifting rod and bolt connected packing gland flange (OS&Y); Valve cover with bolted connection, flexible joint, welded or threaded connection and tight welding.   b. Class 1500 valve, with threaded connection, socket weld connection, butt weld connection or flange connection at the end; Outer screw and bracket with lifting rod, and packing sealing cover flange connected by bolts; Valve cover with bolted connection, flexible joint, welded or threaded connection and tight welding.  

c. 150， 300 and 600 class valves, with flanged or butt welded ends, external screws and brackets with lifting rods; Bolt connected packing sealing gland flange; Valve cover with bolted connection, flexible joint, welded or threaded connection and tight welding.  

Valves with extended valve bodies of Class 800 and 1500 meet the requirements of items a and b above, except that in NPS 1/2, 3/4, 1, 1 1 1/2, and 2 specifications, one end is a convex end, the other end is a concave end, and the other end of the concave end of NPS 1/2 is a convex end of NPS 3/4.

.   The threaded convex end in Class 1500 or NPS 1/2 specification in Class 800 are not included in this standard.  

f. With bellows valve stem seal, Class 150, 300, 600, 800, and 1500 with additional requirements