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1、I MSS SP-70-1998 Cast Iron Gate Valves Flanged and Threaded Ends Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.127 Park Street,NE Vienna,Virginia 22180(703)281-661 3 COPYRIGHT Manufacturers Standardization Society of the
2、Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesSTD*MSS SP-70-ENGL L778 H 5770b40 050LOb8 bllO MSS STANDARD PRACTICE SP-70 An MSS Standard Practice is intended as a basis for
3、common practice by the manufacturer,the user,and the general public.The existence of an MSS Standard Practice does not in itself preclude the manufacture,sale,or use of products not conforming to the Standard Practice.Mandatory conformance is established only by reference i n a code,specification,sa
4、les contract,or public law,as applicable.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 C.In this Standard Practice d notes,annexes,an
5、d figures are construed to be essential to the understanding ofthe message of the standard,and are considered part of the text unless noted as supplemental.All footnotes appearing in this document are construed as supplemental where their information does not modify the text to which they refer.U.S.
6、customary units in this SP are the standard;the metric units are for reference only.I Substantive changes in this 1998 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 flaged with that in the
7、previous edition.I Any part of this standmd may be quoted.Credit lines should read Extracted porn MSS SP-70,1998,with penniwwn o f the publisher,the Manufacturers Standardization Society.Reproduction prohibited under copyright convention unless written permwwn is granted by the Manufacturers Standar
8、dization Society of the Vahe and Fittings Inhtry,Inc.OrigbUy Approved 1970 Copyright 8,1984 by Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.printed i n U.S.A.i COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling Se
9、rvicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesMSS STANDARD PRACTICE SP-70 FOREWORD The 1998 edition of MSS SP-70,in addition to various editorial changes,includes changes to:provide a more complete metric version for reference
10、 use,delete the Class 800 Pressure-Temperature rating,and expand Annex C to include IS0 references.COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by In
11、formation Handling ServicesMSS STANDARD PRACTICE SP-70 CONTENTS SECTION PAGE FOREWORD.ii.CONTENTS.m 1.SCOPE.1 2.VALVE DESIGNATION.CLASSES AND SIZES.1 3.PRESSURE-TEMPERATURE RATINGS.1 4.MATERIALS.1 5.DESIGN.2 6.WORKMANSHIP.4 7.TESTS.4 8.MARKING.4 9.PAINTING.4 TABLE 1.PRESSURE-TEMPERATURE RATINGS.NON-
12、SHOCK-psi.2 TABLE 2.HYDROSTATIC OR GAS SHELL TEST PRESSURE.4 TABLE 3.DURATION OF TESTS.,.4 TABLE B1.PRESSURE-TEMPERATURE RATINGS,NON-SHOCK-bar.8 FIGURE 1.RISING STEM.SOLDWEDGE GATE VALVE.TYPE I.5 2-NON-RISING STEM.SOLDWEDGE GATE VALVE.TYPE I.5 3-RISING STEM.SPLIT-WEDGE GATE VALVE.TYPE II.6 4-NON-RIS
13、ING STEM.SPLITWEDGE GATE VALVE.TYPE II.6 5-RISING STEM.DOUBLE-DISC.PARALLEL SEAT GATE VALVE.TYPE III.7 6-NON-RISING STEM.D0UBLE.DISC.PARALLEL SEAT GATE VALVE.TYPE III.7 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufac
14、turers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesMSS STANDARD PRACTICE SP-70 SCOPE 1.-I.1 This standard practice covers cast iron gate valves with flanged or threaded ends.1.2 These valves are suitable within the sizes and pressure-temperature ratings
15、specified herein for general purpose service.1.3 This standard practice also includes,directly or by reference,stipulations on chemical and physical properties of materials,and dimensions of end connections in common use.2.VALVE DESIGNATION,CLASSES AND SIZES 2.1 Valve Types.Valve types covered herei
16、n are illustrated in Figures A 1,A2,A3,A4,A5,and A6 in Annex A.Type I-Solid Wedge Disc Type II-Split Wedge Disc Type Ill-Double Disc,Parallel Seat Note:The valve sketches herein are for the purpose of illustration and nomenclature only.They are not intended to exclude any design meeting this Standar
17、d Practice.2.2 Construction Designation NT-Non-Rising Stem,Threaded End-NF-Non-Rising Stem,Flanged End OT-Outside Screw and Yoke,Threaded End OF-Outside Screw and Yoke,Flanged End 2.3 T-(a)All Bronze(b)All Iron(c)Bronze with Ferrous Stem I(d)Non-Metallic Seating 2.4 Classes 125 250 I 2.5 sizes.(a)NP
18、S 2-48 N5&1200),flanged end(b)NPS 2-6 N50-150),threaded end I 3.PRESSURE-TEMPERATURE RATINGS 4.I 3.1 Pressure-temperature ratings for the various classes of valves are shown in Table 1.Metric units(bar)are shown in Table BI in Annex B.The ratings specified are for valves with metal-to-metal seating
19、surfaces.Pressure-temperature ratings for valves with non-metallic seat materials must be limited to reflect the physical characteristics of these materials at each temperature,and may be lower but in no case higher than the values shown in Tables 1 and B 1.3.2 The temperature shown for the correspo
20、nding rating shah be the metal temperature of the pressure retaining parts.It shall be assumed that the metal temperature will be the temperature of the contained fluid.Use of a pressure rating at a metal temperature other than that of the contained fluid shall be the responsibility of the user.MATE
21、RIALS 4.1 General.This standard practice is intended to cover minimum physical and chemical requirements.Materials of superior mechanical properties may be substituted.Users are cautioned against applications with fluids which may react chemically with any materials used in these valves.Consultation
22、 with the manufacturer is advised to determine suitability in cases of doubt.4.1.1 Body and Bonnet.Body and Bonnet shall be gray iron in accordance with ASTM A 126 Class B or ductile iron in accordance with ASTM A 536 or ASTM A 395.I 4.1.2 Seating Material.Metal-to-metal seating sur-faces shall be b
23、rass or bronze for bronze mounted valves;cast iron or other ferrous material for all-iron valves.Other materials suitable for the intended service may be furnished when agreed between pur-chaser and manufacturer.4.1.3 Stems.Stem material shall be brass or bronze,either cast or wrought for bronze mou
24、nted valves,wrought steel for all-iron valves.4.1.4 Handwheels.Handwheels may be gray iron,ductile iron,malleable iron or steel at the manufac-turers option.COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Stand
25、ardization Society of the Valve and FittingsLicensed by Information Handling ServicesMSS STANDARD PRACTICE SP-70 I TABLE 1-PRESSURETEMPERATURE RATINGS,NON-SHWK-psi I CLASS 125 CLASS 250 Temp.14-24 2-12 30-48 14-24 2-12 Degrees F.NPS NPS NPS NPS NPS-20 to 150 300 500 150 150 200 200 270 440 100 130 1
26、80 225,280 460 115 135 190 250 275 260 415 85 125 175 220 335 100 150 350 230 355 105 155 325 250 395 65 120 1 70 300 240 375 50 110 165 375 200 290 140 400 210 315 145 I 425 250 125 450 270 130*.See Table BI for Metric U&.4.1.5 Bo Bolts and studs connecting pressure contahg-p-3s shall develop physi
27、cal strength not less than requirements-of ASTM A 307.4.1.6 Glands,Glands shall be made from brass,bronze,gray iron or other ferrous material.5.DESIGN I 5.1*c&When under the test pressure speci-fied in Skctio 7,valves shall be designed to prevent permanent distortion of the body,bonnet,or s e a t s.
28、I Valve stems shall be desiped to prevent permanent distortion when the valve is operated a t full rated working pressure.52 ip#&es shall be integral with the valve body.Dimensions,toleran&and drilling shall be in accordance with ASME B16.1 for each respective pressure class.The flanges shall be ful
29、ly,m c h i n e d on the joint side in accordance with MSS SP-6,(b)Faceto-face dimensions of flanged end valves shall be as follows:-d g e ASME B16.10 NPS 3W;*(DN750-1200)NPS 2-24 (DN5G600)Double Disc (Parallel Seat)Sizes 2-12;ASME B16.10 NPS 1418.*(DN350-450)Class 250(PN501 Solid or Split Wedge&Doub
30、le Disc(Parellel Seat)NPS 2-24(DN50)ASME B16.10.5.3 Threaded Ends.Threaded end bodies may have hexagon,octagon or round ends with ribs.Valve ends shall be threaded with tapered pipe threads in accordance with ASME B 1.20.1.5.4 Body-Boet Bolting(a)Dimensions of bolts and cap screws shall be in accord
31、ance with ASME B18.2.1.Nut dimensions shall be i n accordance with ASME B R 2 2 )Nuts shall be threaded i n accordance with ASME B1.1,Coarse thread series,Class 2B.2 COPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufactur
32、ers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesSTD-MSS SP-70-ENGL L778 5770bYO 0503073 T O B MSS STANDARD PRACTICE SP-70(c)Bolts,studs or cap screws shall be threaded in accordance with ASME B1.1,Coarse thread series,Class 2A.I 5.5 Yokes-Outside Screw a
33、nd Yoke(OS&Y).Yokes on bonnets may be integral or of bolted-on construction.I 5.6 Wedge and Disc Guides and Disc Spreading Device(a)Wedge discs shall be guided to ensure that the seating surfaces of the wedge will not touch the body seat surfaces until near the point of closure.(b)Double discs shall
34、 be provided with guides or linkage or disc spreading devices between the gates or a combination of these which will hold the gates in proper relation with each other and the stem,and will prevent the seat-ing surfaces from rubbing against the body or bonnet during operation.(c)Body guides shall be
35、cast integral with the body except that NPS 16(DN400)and larger may have separate guides of bronze or other bearing material securely fasteded to the body.All guide surfaces shall be smooth and true.I I(d)Selection of material for disc spreading devices shall be the manufacturers option.5.7 Seating
36、Surfaces(a)Disc seating surfaces may be integral or may be separate rings securely fastened to the disc.(b)Body seats shall be separate rings,either shoulder or bottom seated,except that all-iron valve seats may be integral with the body casting at the manufacturers option.Driving lugs may protrude
37、into and reduce port area.5.8 Glands(a)Glands may be threaded or bolted type.(c)Stem seals not requiring a gland,but suitable for the service conditions,may be furnished.5.9 Gland Bolting.Studs,stud bolts,hinge bolts or headed bolts through drilled or slotted holes in the stuffing box flange may be
38、used.In all cases,gland bolting shall be securely held in place and shall provide adequate adjustment for progressive compression of packing material.5.10 Backseat.Valves shall be designed to have a backseat.Repacking under pressure is hazardous and is not recommended.5.11 Stems(a)The upper end of o
39、utside screw and yoke valve stems and the lower end of non-rising valve stems shall be threaded with single or multiple Acme type thread,or Uegree thread approximating the stub form,pre-cision cut to fit the engaging member.(b)Outside screw and yoke stems shall be of sufficient length so as to be at
40、 least flush with the top of the yoke nut after the disc wedging has been worn into its lowest posi-tion.The design shall be such as to prevent any possibility of the wedge or disc leaving the stem,or the stem turning during the operation of the valve.(c)Non-rising stem gate valves having sep-arate
41、stem engaging members shall be so designed as to prevent rotation or pulling out of the disc or wedge.5.12 Handwheels.Handwheels shall be of the spoke type only.Webbed or disc type are not per-missible.Handwheels shall be marked with the direction of movement for opening of the valve.5.13 Bypass and
42、 Drain Connections.Unless other-wise specified,bypass and drain connections shall be in accordance with MSS SP-45.(b)Bolted glands may be solid,solid-bushed,or two-pieced self aligning design.Use of open bolt slots in glands shall not be per-mitted unless hinge bolts are used.3 COPYRIGHT Manufacture
43、rs Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesCOPYRIGHT Manufacturers Standardization Society of the Valve and FittingsLicensed by Information Handling ServicesW S STANDARD PRACTICE SP-70 6 YORKMANSHIP 6.1 General.Valve parts shall be designed and manuf
44、acturing tolerances set so as to provide inter-changeability in the product of any one manufacturer between units of the same size,class,type,and design,except the individual fit of the wedge or disc in the body.6.2 Castin All castings shall be clean and sound without+efects which will impair their
45、servi.No plugging,impregnation,welding or repairing of such defects w i l l be allowed.7.TESTS 7.1 Generala A shell test and a seat test shall be made on all completed valves prior to shipment by the manufacturer.7.2 Shell Test.Valves in the partially open posi-tion with both ends closed.shall be su
46、bjected to hydrostatic or gas test pressure specified in Table 2.No visible leakage i s permitted through the pressure boundary walls or body-bonnet joint.Leakage through the stem packing or stem seals shall not be cause for rejection.The test pressure shall be held for the duration specified in Tab
47、le 3.Caution:Safety precautions must be taken when gsisused.I TABLE 2-SHELL TEST PRESSURE,MINIMUM 1 Max.Servi Rating lSOF(6X)Test Pressure Psi 1 0.3 150 bar Psi bru 3 6.2 525 2 0.7 300 24.1 350 1 3.8#)o 1 8.3 265 60.3 c 5Qo 875 34.5 7.3 Hydrostatic Seat Test:Valves shall be sub-jected to a hydrostat
48、ic seit test at not less than the maximum service pressure for which the valve is rated.Test pressure shall be applied successively on each side of the closed gate,and the opposite side checked for leakage.As an alternate method for double disc valves,the pressure may be applied inside the bonnet or
49、 body with the discs closed and both sides checked for leakage.The maximum permissible leakage rate on each seat shall be 10 milliliters per hour per inch of diameter of nominal valve size(.O7 mm3/sec x DN).Test pressures shall be held for periods specified in Table 3.TABU 3-TEST DURATION,SECONDS,MI
50、NIMUM I t i 250-450 120 7.4 Gas Seat Test.At the manufacturers option,a gas seat test of not less than 80 psi(5.5 bar)may be used in lieu of Hydrostatic Seat Test(7.3).The gas gressure is to be applied as specified for hydrostatic seat test.The maximum permissible leakage rate for each gate seat sha