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1、HIGH PRESSURE BUlTERFLY VALVES WITH OFFSET DESIGN Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.127 Park Street,NE Vienna,Virginia 221 80(703)281 -661 3 COPYRIGHT Manufacturers Standardization Society of the Valve and Fit
2、tingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesMSS STANDARD.PRACTICE SP-68 An MSS Standard Practice is intended as a basis for common practice by the manufacturer,the user,and the general
3、 public.The existence of an MSS Standard Practice does not in itself preclude the manufac-ture,sale,or use of products not conforming to the Standard Practice.Mandatory conformance is established only by reference in a code,specification,sales contract,or public law,as applicable.U.S.customary units
4、 in this SP are the standard;the metric units are for reference only.I Substantive changes in this 1997 edition are“flagged”by parallel bars as shown on the margins of this paragraph.The specific detail of the change may be determined by comparing the material flagged with that in the previous editi
5、on.I Unless otherwise specifically noted in this MSS SP,any standard referred to herein is identified by the date of issue that was applicable to the referenced standard(s)at the date of issue of this MSS SP.(See Annex A.)Any part o f this standard may be quoted.Credit lines should read Extracted fr
6、om MSS SP-68,1997,with permission o f the publisher,the Manufacturers Standardization Society.Reproduction prohibited under copyright convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.Originally Approved October 1984 C
7、opyright O,1984 by Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.Printed in U.S.A.1 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and Fittin
8、gsLicensed by Information Handling ServicesSTD*MSS SP-b8-ENGL L977 5770b40 0500954 3T7 MSS STANDARD PRACTICE SP-68 CONTENTS Section Page CONTENTS.ii 1.SCOPE.1 2.DESIGN REQUIREMENTS.1 3.FACE-TO-FACE DIMENSIONS.2 4.MARKING.2 5.TESTING.2 TABLE Al DISC TO PIPE MINIMUM NOMINAL RADIAL CLEARANCES.4 FIGURE
9、Al NOMENCLATURE AND EXPLANATION OF NOMINAL RADIAL CLEARANCE.;.4 ANNEX A DISC TO PIPE CLEARANCE.4 ANNEXB REFERENCEDSTANDARDS.5 ii COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Va
10、lve and FittingsLicensed by Information Handling ServicesMSS.STANDARD PRA.CTICE SP-68 HIGH PRESSURE BUlTERFLY VALVES WITH OFFSET DESIGN 1.SCOPE 1.1 This standard practice covers design require-ments,test performance,marking requirements,and nomenclature for butterfly valves designed for high pressur
11、e performance,having a seat plane offset from the plane of the stem centerline.1.2 This standard practice covers flangeless (wafer type)and single flanged(lug type)body designs,Compatible with ASME/ANSI B16.5 flanges for sizes NPS 3(DN 80)through NPS 24(DN 600)and ASME/ANSI B16.47 Series A flanges f
12、or sizes NPS 30(DN 750)through NPS 48(DN 1200).Reference Tables 1 and 2.1.3 This standard practice covers valves having body pressure temperature ratings in accordance with ASME/ANSI B16.34.1.4 Definitions may be found in MSS SP-96.2.DESIGN REQUIREMENTS 2.1 Valve Flange Gasket Surfaces.The flange ga
13、s-ket surfaces of the valve body(against the mating flanges)shall be flush witli or.raised from other body surfaces within the outside diameters of the mating flanges.2.2 Flange Bolting 2.2.1 Threaded holes used for flange bolting shall provide for full thread engagement to a depth of not less than
14、1.O times the nominal bolt diameter.2.2.2 Unless otherwise specified by the customer,threaded holes for flange bolting shall be tapped in accordance with ASME B1.l Coarse Thread Series Class 2B for bolts 1 inch and smaller and shall be tapped to the 8-Thread Series Class 2B for bolts I 1 h1 and larg
15、er.2.3.Minimum Disc-Pipe Clearance I 2.3.1 The valve disc will upon rotation project beyond the body flange gasket surfaces and there-fore requires care on the part of the user to insure that,when installed,there is no interference between the valve disc and adjacent components such as pip-ing,strai
16、ners,check valves and other valving.Also mating pipe flanges should be carefully aligned prior to tightening of the companion flange bolts.2.3.2 The valves shall be designed to be compatible with Schedule 40 pipe for all sizes of Class 150(PN 20);with Schedule 80 pipe for all sizes of Class 300(PN 5
17、0)and with Schedule 80 pipe for the NPS 3(DN 80)through NPS 6(DN 150)sizes and Schedule 100 for sizes NPS 8(DN 200)through NPS 24(DN 600)of Class 600(PN 100).2.3.3.All valves shall be designed for disc-pipe clearance according to the requirements of Annex A.2.3.4 When the user elects to use a heavie
18、r sched-ule pipe than listed in 2.3.2,it shall be his responsi-bility to insure disc/pipe clearance.2.4.Minimum Wall Sections.All valves shall have a minimum wall thickness as required by ASME/ANSI B16.34 for the rating marked on the identif-cation plate.2.5 Special Requirements for Single Flange(Lu
19、g Type)Valves.Single flange(lug type)valves may be designed for closure in dead-end piping when installed against a single flange.Such condition may also ccur after removing the companion flange and piping from one side of the valve.Single flange(lug type)valves which have every flange bolt hole thr
20、eaded shall be designed such that all parts which are necessary to support pressure loads acting across the seating element safely support the maximum differential pressure rating of the valve.Examples of such parts are seat seal retaining plates and their bolting or retaining means.In the event tha
21、t the valve design cannot accommodate these 1 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesSTD*MSS SP-b8-ENGL L777=57
22、70b40 050075b L7T MSS ST ANDARD PRACT I CE SP-68 3.pressure loads,the valve shall be marked to show installation or application restrictions.2.6 External Disc Position Indicator.All valves shall have a means to indicate the disc position.The design shall be such that the components can-not be assemb
23、led to falsely indicate the open or closed position of the valve.FACE TO FACE DIMENSIONS 3.1 Valve body face-to-face dimensions for sizes NPS 3 (DN 80)through NPS 24(DN 600)flangeless(wafer type)and single flange (lug type)valves and tolerance or variances are listed in Table 1.I TABLE 1.FACE-TO-FAC
24、E DIMENSIONS()I Valve Class 600 Class 300 Class 150 Size(PN 20)54 2.12 48 1.88 48 1.88 80 3 mm in mm in mm in DN IPS(PN 100)(PN 50)4 100 2.12 54 2.12 232 9.13 181 7.12 154 6.06 600 24 E 8.50 159 6.25 127 5.00 500 20 7.88 149 5.88 114 4.50 450 18 178 7.00 133 5.25 101 4.00 400 16 155 6.12 117 4.62 92
25、 3.62 350 14 140 5.50 92 3.62 81 3.19 300 12 117 4.62 83 3.25 71 2.81 250 10 102 4.00 73 2.88 63 2.50 200 8 78 3.06 59 2.31 57 2.25 150 6 64 2.50 54(a)Note:Tolerance/variance not to exceed L.I3 inch(3.5 mm).3.2 Valve body face-to-face dimensions for sizes NPS 30(DN 750)through NPS 48(DN 1200)Class 1
26、50(PN 20)valves and tolerances or variances are listed for three body types in Table 2.These body face-to-face dimensions are an adaptation of MSS SP-67 Wide,API 609 Category B,and ASME B16.10 Wide for Type 1,IS0 5752 Series 20-for Type 2,and IS0 5752 Series 16 for Type 3.I TABLE 2.FACE-TO-FACE DIME
27、NSIONS()I Valve Size Type2 I Type3 NPS mm in mm in mm in DN 30 750 350 13.78 254 10.00 276 10.88 1200 48 300 11.81 229 9.00 246 9.68 1100 42 241 9.50 203 8.00 200 7.88 900 36 230 9.05 191 7.50 165 6.50 b,Note:Tolerance/variance not to exceed f.25 inch(6.4 mm).4.MARKING 4.1 Valves shall be marked in
28、accordance with MSS SP-25.When the maximum differential shut-off pressure at any temperature is less than the body pressure rating at that temperature,this limit shall also be shown on the permanently affixed identification plate.4.2 Valves designated for shutoff in a required direction(one way valv
29、es)shall be clearly and per-manently marked to identify the high pressure side or direction of flow.4.3 Valves conforming to the requirements of this Standard Practice may be marked SP-68 on the identification plate.5.TESTING 5.1 Shell Test.Each valve shall be given a shell test at a gage pressure n
30、o less than 1.5 times the 100F(38C)rating,rounded off the next higher 25 psi(1 bar)increment.The test shall be made with water,which may contain a corrosion inhibitor,or with kerosene,or with other suitable fluid(liquid or gas),provided such fluid has viscosity not greater than that of water,at a te
31、mperature not above 125F(52C).Visually detectable leakage through pressure boundary walls is not acceptable.Test duration shall not be less than shown in Table 3.2 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturer
32、s Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesM S S S T A N D A R D P R A C T I C E SP-68 I TABLE 3.SHELL TEST DURATION I Valve Size Seconds,Minimum DN NPS Shell Test Duration i t 3-8 120 500-1200 2048 60 250450 10-18 30 80-200 The test shall be made wit
33、h the valve in the partially open position.Leakage through the stem packing shall not be cause for rejection if the manufacturer can demonstrate that the shaft seal design is capa-ble of sealing at 1.1 times the maximum rated pres-sure of the valve.5.2 Seat Testing 5.2.1 Each valve shall be tested i
34、n accordance with 5.2.2,5.2.3,or 5.2.4 as appropriate.For bi-directional valves,the test pressure shall be applied across the disc in the direction producing the most adverse seating condition.Valves limited to closure against differential pressure in one direction(see 4.2)shall be tested in that di
35、rection.5.2.2 Each valve furnished for shutoff or isola-tion service shall be subjected to a seat test using fluid as described in 5.1.at 1.1 times the shutoff differential pressure rating of the valve at ambient temperature.No visible leakage through the body or the disc or past the seat shall be a
36、llowed.Test duration shall not be less than shown in Table 4.I TABLE4.SEATTEST DURATION I Valve Size Seconds,Minimum DN NPS Seat Test Duration 3-8 1 20 500-1200 2048 60 250450 10-18 30 80-200 5.2.3 Each valve furnished for shutoffor isola-tion applications,where seat leakage is permissible,shall be
37、tested as specified in 5.2.2 except that leak-age past the seal shall not exceed the maximum leakage allowance specified by the purchaser.5.2.4 Each valve furnished for services other than shutoff or isolation shall be tested at a pressure and with seat leakage allowance as agreed upon by manufactur
38、er and purchaser.5.2.5 Leakage detection devices,e.g.,pressure decay devices may be used for detecting leakage provided that they are used at the pressures required for the shell and closure tests of paragraphs 5.1 and 5.2.When used,the valve manufacturer shall have demonstrated that the test result
39、s are equivalent to the requirements of paragraphs 5.1 and 5.2.6.5.2.6 For automatic leak detection methods,the term“no visible leakage”is as a leakage rate no greater than 5 x 10-6 in3/sec(8 x lo-ml/sec)per valve NPS();Test duration shall be as shown in Section 5.2.2.NOTE The footnote below is for
40、supplementary purposes and is not part of the standard.This leakage rate is based on the measured leakage of nitrogen gas from a needle valve with a 0.167”O.D.x 0.091 1.D.tube discharge submerged in water to a depth of 1”.The tube end was cut square and smooth with no chamfers or burrs and the tube
41、axis was parallel to the surface of the water.Leakage was adjusted to a level equal to 40 bubbles in 10 minutes at 90 psi.The 40 bubbles equaled 1.6 ml or,1 bubble=0.04 SCC.Using these data,a leak rate equivalent to 1 bubble every minute is found to be4.1*IO5 in3/sec(6.7 x lo4 ml/sec).3 COPYRIGHT Ma
42、nufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesSTD-MSS SP-b8-ENGL L777 5770biO 0500758 Ti2 M S S S T A N D A R D P R A C T I C E SP
43、-68 ANNEX A DISC TO PIPE CLEARANCE In accordance with paragraphs 2.3.2 and 2.3.3 of this Standard Practice,butterfly valves shall be designed to have clearance with the inside diameter of adjacent pipe.Minimum nominal clearances are shown in Table AI of this Annex.TABLE Al.DISC TO PIPE MINIMUM NOMIN
44、AL RADIAL CLEARANCES Valve Size Minimum Nominal Radial Clearance with Valve NPS Centered with Pipe Using L/16 Inch(1.5 mm)Thick Gaskets DN up to 6 up to 150 0.25 inch (6.5 mm)600 and larger 24 and larger 0.12 inch (3.0 mm)200 through 500 8 through 20 0.06inch(1.5 mm)Note a:The minimum clearance cond
45、ition may exist when the disc is either in a partially open or the full open position depending on the design.Note b:Larger discs may be used for designs that allow for alignment of the pipe with the disc provided that it can be demonstrated by worst case calculations that the pipe will not interfer
46、e with disc rotation.Note c:See Figure Al for typical illustration and nomenclature.FACE TO FACE DIMENSION DISC CENTERLINE STEM CENTERLINE SEAT RETAINER PICTORIAL REPRESENTA1 PURPOSES ONLY AND DO SEAT OFFSET ARE FOR ILLUSTRATIVE STEM CENTERLINE _-,PIPE CENTERLINE IMPLY DESIGN.(AXIS OF ROTATION)SECTI
47、ON A-A STEM OFFSET r-STEM CENTERLINE IONS NOT STEM CENTERLINE DISC CENTERLINE DISC CLEARANCE IN THE FULLY OPEN DISC POSITION (SEE NOTE a OF THIS ANNEX).SECTION B-B CLEARANCE IN THE FULLY OPEN DISC POSITION (SEE NOTE a OF THIS ANNEX).SECTION B-B FIGURE Al.NOMENCLATURE AND EXPLANATION OF NOMINAL RADIA
48、L CLEARANCE 4 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesM S S S T A N D A R D P R A C T I C E SP-68 ANNEX B REFERE
49、NCED STANDARDS This Annex is an integral part of the Standard Practice which is placed after the main text for convenience.List of standards and specifications referenced in this Standard Practice show the year of approval.ASME.ANSIIASME.ANSI.ASMEIANSI B1.l-1989 Unified Inch Screw Threads (UN&UNR Th
50、read Form)B1.5-1988 Acme Screw Threads B16.34-1996 Valves-Flanged,Threaded&Welding End B16.47-1996 Large Diameter Steel Flanges:NPS 26 Through NPS 60 MSS-MSS SP-96-1996 Guidelines on Terminology for Valves and Fittings Publications of the following organizations appear on the above list:ANSI ASME MS