Reduced-opening valves with a noncircular opening and reduced-opening check valves shall be designated as reduced-bore valves and specified by the nominal size corresponding to the end connections followed by the letter “R。” EXAMPLE 2 Reduced-bore valve with NPS 16 (DN 400) end connections and a 15 × 12 (381 mm × 305 mm) rectangular opening shall be specified as 16R。
4。4Valve Operation
The purchaser should specify the method of operation and the maximum pressure differential (MPD) at which the valve is required to be opened by the lever, gearbox, or actuator。 If not specified, the pressure as determined in accordance with 5。2 for material at 100 °F (38 °C) shall be the MPD。
The manufacturer shall provide the following data to the purchaser, if requested:
—flow coefficient Cv or Kv;
—breakaway thrust or torque for new valve and the breakaway travel or angle;
—valve run thrust or torque;
—maximum allowable stem thrust or torque on the valve and, if applicable, the maximum allowable input torque to the gearbox;
—number of turns for manually operated valves。
4。5Pigging
The purchaser shall specify the requirements for piggability of the valves。
4。6Valve Ends
4。6。1Flanged Ends
4。6。1。1General
Flanges shall be furnished with a raised face or ring joint face (raised face or full face)。 Specified dimensions, tolerances, and finishes, including drilling templates, flange facing, nut-bearing surfaces (i。e。 spot facing and back facing), outside diameters, and thickness (see Figure
1) shall be in accordance with:
—ASME B16。5 for sizes up to and including NPS 24 (DN 600) except NPS 22 (DN 550);
—MSS SP-44 for NPS 22 (DN 550); and
—ASME B16。47, Series A for NPS 26 (DN 650) and larger sizes。
If none of the above standards applies, the selection of another design code or standard shall be made by agreement。
For valves with heavy wall sections, flanges with nut stops in accordance with Mandatory Appendix 2, Figure 2-4 (Sketch 12 or 12a) of ASME BPVC, Section VIII, Division 1 may be required。 The manufacturing method shall ensure flange alignment in accordance with 4。7。1。2, 4。7。1。3, and 4。7。1。4。
4。6。1。2Offset of Aligned Flange Centerlines—Lateral Alignment
For valves up to and including NPS 4 (DN 100), the maximum flange misalignment shall be 0。079 in。 (2 mm)
For valves larger than NPS 4 (DN 100), the maximum flange misalignment shall be 0。118 in。 (3 mm)。
4。6。1。3Parallelism of Aligned Flange Faces—Angular Alignment
The maximum measured difference between flanges shall be 0。03 in。/ft (2。5 mm/m)。
4。6。1。4Total Allowable Misalignment of Bolt Holes
For valves up to and including NPS 4 (DN 100), the maximum total allowable misalignment shall be no greater than 0。079 in。 (2 mm) at the bolt holes (see Figure 2)。
For valves larger than NPS 4 (DN 100), the maximum total allowable misalignment shall be equivalent to 0。118 in。 (3 mm) at the bolt holes。
The surface of the nut bearing area at the back face of flanged valves shall be parallel to within 1° of the flange face。
4。6。2Welding Ends
Welding ends shall conform to ASME B31。3, ASME B31。4, or ASME B31。8, unless otherwise agreed。 In the case of a heavy-wall valve body, the outside profile may be tapered at 30° and then to 45° as illustrated in ASME B16。25。
The purchaser shall specify the outside diameter, wall thickness, material grade, specified minimum yield strength (SMYS) and any special chemistry of the mating pipe, and whether cladding has been applied。 撑开式闸阀设计英文文献和中文翻译(7):http://www.youerw.com/fanyi/lunwen_97242.html