API 599:2020 pdf free download.Metal Plug Valves—Flanged, Threaded, and Welding Ends
5.4.4 If the surfaces of plugs that rotate against elastomeric or plastic sleeves, liners, seals, gaskets, or seats are not coated with an elastomer or plastic, these surfaces of plugs shall have a surface fnish no rougher than Ra of 0.40 μm (16 μin.) in accordance with ASME B46.1. Lubricated plug valves shall have a surface fnish between the seat and plug that will insure maximum retention of lubricant as determined by the manufacturer.
5.4.5 Stem surface area in contact with the stem seal or packing shall be no rougher than Ra of 0.80 μm (32 μin.) in accordance with ASME B46.1. Energized seals may have surface fnish requirements that fall outside of this range. 5.4.6 Sealing for lubricated taper plug valves shall be a metal-to-metal seated design.
5.5 Glands
5.5.1 Adjustable glands or gland followers may be a threaded type, a bolted one-piece type, or a bolted two- piece, self-aligning type.
5.5.2 Packing glands that are threaded into bodies or covers or onto stems shall not be used for valve sizes greater than DN 100 (NPS 4) unless otherwise specifed by purchase order. 5.5.3 The gland shall be of a design that allows entry into the stufng box while minimizing the potential for extrusion when compressing the packing rings.
5.6 Bolting
5.6.1 Covers shall be bolted with studs, stud bolts, or cap screws. Studs and stud bolts shall be equipped with heavy hex nuts that conform to ASME B18.2.2 or ASME B18.2.6 and sizing in accordance with ASME B16.34 or ASME BPVC Section VIII, Division 1, Appendix 2.
5.6.2 Bonnet/cover/gland bolting with diameters 25 mm (1 in.) and smaller shall have coarse (UNC) threads or the most nearly corresponding metric thread. Bolting with diameters larger than 25 mm (1 in.) shall be 8-thread series (8 UN) or the most nearly corresponding metric threads. Bolt threads shall be Class 2A and nut threads shall be Class 2B, in accordance with ASME B1.1. When wrench-ft studs are furnished, the wrench-ft end of these studs and the threaded hole shall have threads in accordance with a Class 5 interference ft, as specifed in ASME B1.12. When metric bolting is used, metric bolt threads shall be tolerance Class 6g and nuts tolerance Class 6H in accordance with ASME B1.13M.
5.6.3 Through holes shall be used in the bonnet, cover fange, cover, adjuster, or gland. Open slots shall not be used.
5.6.4 Packing gland bolts shall be designed so that the bolt stress shall not exceed one third ( 1 / 3 ) of the minimum tensile stress of the bolt due to average packing compressive stress required to retain the maximum cold working pressure of the valve (CWP rating).
5.7 Operation
5.7.1 Unless otherwise specifed on the purchase order, the length of the lever handle or the gear ratio, efciency, and handwheel diameter of gear operators shall be designed so that the required input force to fully open and close the valves shall not exceed 360 N (80 lbf) when operating the valve at the manufacturer’s maximum published torque as described in 5.4.3.
5.7.2 A wrench (or lever) shall be furnished as a separate item and shall be supplied only when specifed in the purchase order. A wrench may be of an integral design or may consist of a head that fts onto the stem and is provided with a socket or another suitable means of accommodating an extended handle. The head shall be designed so that the handle can be permanently attached. The head shall be secured to the stem or operating mechanism with a set screw of ample size or by another positive means.
5.7.3 A spoked handwheel shall be furnished with each gear-operated valve; webbed or disked handwheels shall not be used. Spokes that extend beyond the wheel rim (tiller type) are permissible.
5.7.4 Gear mechanisms may be operated manually or by means of an electric motor or another similar power device. Keys or pins shall be used to secure gears or pinions to separate shafts. On power-operated valves, the gear assembly shall be suitably guarded.API 599 pdf download.API 599:2020 pdf free download
