阀门标准-MSS SP-120-2006 Flexible Graphite Packing System for Rising Stem Steel Valves - Design Requirements(天选打工人).pdf

MSS SP-120-2006 www.mss-hq.org 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)281-6613 Email:infomss-hq.org Flexible Graphite Packing System for Rising Stem Steel Valves-Design Requirements MSS Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-120 iThis MSS Standard Practice was developed under the consensus of the MSS Technical Committee 308 and the MSS Coordinating Committee.The content of this Standard Practice is the result of the efforts of competent and concerned volunteers to provide an effective,clear,and non-exclusive specification that will benefit the industry as a whole.This MSS Standard Practice is intended as a basis for common practice by the manufacture,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 in a code,specification,sales contract,or public law,as applicable.U.S.customary units in this SP are the standard;metric(SI)units are for reference only.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 of this standard may be quoted.Credit lines should read Extracted from MSS SP-120,2006,with permission of 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 March 1997 Copyright 1997 by Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.Printed in U.S.A.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-120 ii FOREWORD This Standard Practice was developed by a cooperative effort of representatives of valve and packing manufacturers.This Standard Practice is intended primarily to be an aid for the manufacture and procurement of packing systems with design features for rising-stem steel valves that utilize flexible graphite packing.However,this does not preclude the use of these system features for other types of packing systems since this Standard Practice represents the consensus input from a broad spectrum of industry applications.This Standard Practice shall not be construed to be effective for all pressures and types of services expected of ASME B16.34 valves.Special service applications such as low fugitive emissions control or toxic fluid may require additional or different design measures that are outside the scope of this Standard Practice.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-120 iiiTABLE OF CONTENTS SECTION PAGE 1 SCOPE.1 2 DEFINITIONS.1 3 PACKING ASSEMBLY.1 4 STEM.2 5 PACKING GLAND.2 6 PACKING CHAMBER.2 7 PACKING WASHER OR VALVE BONNET.2 TABLE 1 Packing System Details(U.S.Units).3 2 Packing System Details(Metric Units).4 FIGURE 1 Packing System Details(U.S.Units).3 2 Packing System Details(Metric Units).4 3 Stem/Bonnet Details(U.S.Units).5 4 Stem/Bonnet Details(Metric Units).6 5 Geometric Symbols Definitions.7 ANNEX A Referenced Standards and Applicable Dates.8 Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-120 1FLEXIBLE GRAPHITE PACKING SYSTEM FOR RISING STEM STEEL VALVES-DESIGN REQUIREMENTS 1.SCOPE(1)1.1 This Standard Practice establishes material and dimensional requirements for valve packing,packing chamber,packing gland,packing washer,bonnet,and stem as they relate to the total packing assembly.1.2 This Standard Practice applies to standard,special,and limited Class 150 through Class 4500(including intermediate classes)ASME B16.34 type steel gate,globe,and angle valves designed with rotating/rising and non-rotating/rising stems.1.3 This Standard Practice applies to valves in which a flexible graphite packing assembly is used as the primary stem-sealing system.1.4 This Standard Practice does not apply to valves that include a lantern ring as part of its packing system nor to bonnetless valves with split glands.2.DEFINITIONS 2.1 See MSS SP-96 for definitions of terms used in this Standard Practice.2.2 See Figure 5 for definitions of symbols used in this Standard Practice.3.PACKING ASSEMBLY 3.1 The packing shall be composed of center and end rings or a cylinder of flexible graphite and end rings.A flexible graphite packing assembly that is NOTE:(1)This Standard Practice is not intended to apply to valves developed for and predominantly used in instrument piping systems.(See MSS SP-99 and MSS SP-105)constructed with a braided carbon or braided graphite or metal-mesh that reinforces the flexible graphite may not require end rings.The end rings shall serve as wipers and anti-extrusion devices to keep the flexible graphite in the packing chamber during operation,including stroking,of the valve.Individual center rings may contain up to 2 splits per ring to facilitate valve packing installation.Braided end rings shall contain a maximum of 1 split per ring and molded end rings shall contain a maximum of 2 splits per ring.The end ring properties shall be designed to deter the extrusion and/or erosion of the center flexible graphite rings during valve operation.Packing assemblies of flexible graphite without end rings may be used;however,the diametrical clearance specified in Table 1 and Table 2 shall be reduced to a maximum of 50%of that required for higher than Class 300 valves.The packing shall also be qualified to the requirements of MSS SP-121.3.2 The packing assembly shall contain a dispersed passive corrosion-inhibitor,a dispersed embedded active corrosion-inhibitor,or a suitable combination of inhibitors,to minimize stem pitting caused by the galvanic corrosion phenomenon set up in a wet valve packing-chamber.Inhibitors in end rings are optional,unless otherwise specified by the purchaser.3.3 The pre-installed density and dimensions of the flexible graphite packing shall be at the valve manufacturers option.The final adjusted density and dimensions of the packing assembly shall be capable of sealing with no visible leakage when the valve is tested at a pressure equal to the valves 100F pressure rating at ambient conditions.The as-shipped remaining packing and packing gland adjustment(packing gland tight)shall be greater than 10%of the minimum depth of the packing chamber listed in Table 1 and Table 2.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-120 26.PACKING CHAMBER6.1 The dimensional tolerance of the packing chamber shall be such that the maximum diametrical clearance between gland or follower and the packing chamber(A)illustrated in Table 1 and Table 2 is not exceeded.The packing depth 4W or 5W illustrated in Table 1 and Table 2 refers to the equivalent of 4 or 5 square rings of packing which includes the top and bottom end rings.The packing chamber inside diameter surface finish shall be 125 Ra(microinch)(3.2 micrometers)or smoother,as illustrated in Figure 1 and Figure 2.A chamfer or radius may be used at the entrance of the packing chamber.6.2 The packing chamber bore shall meet squareness to the bonnet gasket surface or other appropriate datum surface encompassed in a perpendicularity tolerance of 0.006(0.15mm)regardless of bore size,(see Figures 3 and 4).6.3 The packing chamber bore shall meet circularity,taper,and straightness requirements encompassed in a cylindricity tolerance of 0.006(0.15mm),(see Figures 3 and 4).6.4 The packing chamber bore and bonnet stem hole shall be concentric within a positional tolerance of 0.005(0.13mm)as presented in Figures 3 and 4.6.5 The packing chamber bore shall be free of scratches,pits,or voids deeper than 0.006(0.015mm).7.PACKING WASHER OR VALVE BONNET 7.1 The tolerance on the valve bonnet or the packing washer,when a packing washer is used,shall be such that the maximum diametrical clearance between the stem and the bonnet or packing washer(C),illustrated in Table 1 and Table 2,is not exceeded.3.4 The dimensional requirements of the packing assembly shall be per Table 1 and Table 2.The minimum width W and minimum depth L are listed.3.5 Smaller packing widths(W)and/or smaller depths(L)may be used when qualified to the requirements of MSS SP-121.All other provisions of the Standard Practice shall apply.4.STEM 4.1 The dimensional tolerances(bilateral or unilateral)shall be per Table 1 and Table 2.The stem finish shall be 32 Ra(microinch)(0.80 micrometers)or smoother.These stem characteristics shall apply in the area that contacts the packing during the full stroking of the valve.The stem diameter tolerance as shown in Table 1 and Table 2 applies to the stem diameter that contacts the packing I.D.4.2 The stem diameter tolerance shall be such that the maximum diametrical clearance between the packing gland or follower I.D.(B)and bonnet or packing washer(C)as required in Table 1 and Table 2 is not exceeded.4.3 The stem diameter that contacts the packing during the full stroking of the valve shall meet circularity,taper,and straightness requirements encompassed in a cylindricity tolerance of 0.003(0.08mm)for 3 and smaller stems and 0.004(0.10mm)for stems larger than 3(see Figures 3 and 4).4.4 The stem surface that contacts the packing during full stroking of the valve shall be free of scratches,pits,or voids deeper than 0.002(0.05mm).5.PACKING GLAND5.1 The dimensional tolerances of the gland or follower I.D.and O.D.shall be such that the maximum diametrical clearance between the stem and gland or follower(B)and packing chamber bore and gland or follower(A)illustrated in Table 1 and Table 2 are not exceeded.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-120 3FIGURE 1 Packing System Details(U.S.Units)(Illustrative Only)TABLE 1 Packing System Details(U.S.Units)NOTE,DIMENSIONS ARE IN INCHES WIDTH&DEPTH OF PACKING DIAMETRICAL CLEARANCE-MAXIMUM STEM SIZE STEM DIAMETER TOL.#1-MAXIMUM PACKING CHAMBER I.D.TOL.#2-MAXIMUM W MINIMUM L MINIMUM A (1)B (1)C (1)1/4”thru 1/2”0.008 0.010 1/8 4W.020.040.040 1/2”thru 11/16 0.008 0.010 3/16 4W.020.040.040 11/16”thru 1 1/4”0.008 0.010 1/4 4W.025.050.050 1 1/4”thru 2”0.009 0.010 5/16 5W.025.050.050 2”thru 3”0.011 0.010 3/8 5W.025.050.050 3”thru 3 1/2”0.011 0.015 7/16 5W.030.065.065 3 1/2”thru 4 1/4”0.011 0.015 1/2 5W.030.065.065 4 1/4”thru 5”0.011 0.015 9/16 5W.030.065.065 5”thru 7”0.011 0.015 5/8 5W.030.065.065 General Note:Dimensions are in inches Note(1)The manufacturer may need to revise diametrical clearances for severe services and/or high pressure applications.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-120 4MSS STANDARD PRACTICE SP-120FIGURE 2 Packing System Details(Metric Units)(Illustrative Only)FIGURE 2 Packing System Details(Metric Units)(Illustrative Only)TABLE 2 Packing System Details(Metric Units)TABLE 2 Packing System Details(Metric Units)NOTE:DIMENSIONS ARE IN MILLIMETERS NOTE:DIMENSIONS ARE IN MILLIMETERS WIDTH&DEPTH OF PACKING WIDTH&DEPTH OF PACKING DIAMETRICAL CLEARANCE-MAXIMUM DIAMETRICAL CLEARANCE-MAXIMUM STEM SIZE STEM SIZE STEM DIAMETER TOL.#1-MAXIMUM STEM DIAMETER TOL.#1-MAXIMUM PACKING CHAMBER I.D.TOL.#2-MAXIMUM PACKING CHAMBER I.D.TOL.#2-MAXIMUM W MINIMUMW MINIMUML MINIMUM L MINIMUM A (1)B (1)C (1)6.4 thru 12.7 6.4 thru 12.7 0.20 0.20 0.25 0.25 3.2 3.2 4W 4W 0.51 0.51 1.02 1.02 1.02 1.02 12.7 thru 17.5 12.7 thru 17.5 0.20 0.20 0.25 0.25 4.8 4.8 4W 4W 0.51 0.51 1.02 1.02 1.02 1.02 17.5 thru 31.8 17.5 thru 31.8 0.20 0.20 0.25 0.25 6.4 6.4 4W 4W 0.64 0.64 1.27 1.27 1.27 1.27 31.8 thru 50.8 31.8 thru 50.8 0.23 0.23 0.25 0.25 7.9 7.9 5W 5W 0.64 0.64 1.27 1.27 1.27 1.27 50.8 thru 76.2 50.8 thru 76.2 0.23 0.23 0.25 0.25 9.5 9.5 5W 5W 0.64 0.64 1.27 1.27 1.27 1.27 76.2 thru 88.9 76.2 thru 88.9 0.28 0.28 0.38 0.38 11.1 11.1 5W 5W 0.76 0.76 1.65 1.65 1.65 1.65 88.9 thru 108.0 88.9 thru 108.0 0.28 0.28 0.38 0.38 12.7 12.7 5W 5W 0.76 0.76 1.65 1.65 1.65 1.65 108.0 thru 127.0 108.0 thru 127.0 0.28 0.28 0.38 0.38 14.3 14.3 5W 5W 0.76 0.76 1.65 1.65 1.65 1.65 127.0 thru 178.0 127.0 thru 178.0 0.28 0.28 0.38 0.38 15.9 15.9 5W 5W 0.76 0.76 1.65 1.65 1.65 1.65 General Note:Dimensions are in millimeters General Note:Dimensions are in millimeters Note(1)The manufacturer may need to revise diametrical clearances for severe services and/or high pressure applications.Note(1)The manufacturer may need to revise diametrical clearances for severe services and/or high pressure applications.4 A (1)B (1)C (1)Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-120 5 FIGURE 3 Stem/Bonnet Details(U.S.Units)(Illustrative Only)TYPICAL BONNET TYPICAL STEM Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-120 6 FIGURE 4 Stem/Bonnet Details(Metric Units)(Illustrative Only)TYPICAL BONNET TYPICAL STEM Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-120 7 DATUM FEATUREDEF.A Datum Feature is used to designate a Datum Surface or Feature CYLINDRICITYDEF.Cylindricity is a condition of a surface of revolution in which all points of the surface are equidistant from a common axis.POSITION DEF.A Position Tolerance defines a zone within which the axis or center plane of a feature is permitted to vary from its theoretically exact position.PERPENDICULARITY DEF.Perpendicularity is the condition of a surface,axis or line which is 900 from a Datum Plane Axis.MAXIMUM MATERIAL CONDITION DEF.Maximum Material Condition is that condition where a feature of size contains the maximum amount of material within the stated limits of size.e.g.,smallest hole,biggest shaft.FIGURE 5 Geometric Symbols Definitions(Illustrative only)Copyright MSS Provided by IHS under license with MSSNot for ResaleNo rep