1、 MSS SP-149-2015 Preformed Elastomeric and Polytetrafluoroethylene (PTFE) V-Ring Packing Sets for Waterworks Valves Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE Vienna, Virginia 22180-4602 Phone: (7
2、03) 281-6613 Fax: (703) 281-6671 E-mail: standardsmsshq.org www.msshq.org MSS STANDARD PRACTICE SP-149i This MSS Standard Practice was developed under the consensus of the MSS Technical Committees 308 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts
3、of competent and experienced volunteers to provide an effective, clear, and non-exclusive standard that will benefit the industry as a whole. This MSS Standard Practice describes minimal requirements and is intended as a basis for common practice by the manufacturer, the user, and the general public
4、. 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 to this Standard Practice is established only by reference in other documents such as a code, specification, sales contract
5、, or public law, as applicable. MSS has no power, nor does it undertake, to enforce or certify compliance with this document. Any certification or other statement of compliance with the requirements of this Standard Practice shall not be attributable to MSS and is solely the responsibility of the ce
6、rtifier or maker of the statement. “Unless indicated otherwise within this MSS Standard Practice, other standards documents referenced to herein are identified by the date of issue that was applicable to this Standard Practice at the date of approval of this MSS Standard Practice (see Annex A). This
7、 Standard Practice shall remain silent on the validity of those other standards of prior or subsequent dates of issue even though applicable provisions may not have changed.” By publication of this Standard Practice, no position is taken with respect to the validity of any potential claim(s) or of a
8、ny patent rights in connection therewith. MSS shall not be held responsible for identifying any patent rights. Users are expressly advised that determination of patent rights and the risk of infringement of such rights are entirely their responsibility. In this Standard Practice, all text, notes, an
9、nexes, tables, figures, and references are construed to be essential to the understanding of the message of the standard, and are considered normative unless indicated as “supplemental”. All appendices, if included, that appear in this document are construed as “supplemental”. Note that supplemental
10、 information does not include mandatory requirements. U.S. customary units in this Standard Practice are the standard; the SI (metric) units are for reference only. Excerpts of this Standard Practice may be quoted with permission. Credit lines should read Extracted from MSS SP-149-2015 with permissi
11、on of the publisher, Manufacturers Standardization Society of the Valve and Fittings Industry. Reproduction and/or electronic transmission or dissemination is prohibited under copyright convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fitt
12、ings Industry Inc. All rights reserved. Originally Approved: July 2015 Originally Published: December 2015 MSS is a registered trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright , 2015 by Manufacturers Standardization Society of the Valve and Fittin
13、gs Industry, Inc. Printed in U.S.A. MSS STANDARD PRACTICE SP-149ii TABLE OF CONTENTS SECTION PAGE 1 SCOPE 1 2 DEFINITIONS . 1 3 V-RING PACKING SET MATERIALS 1 4 V-RING PACKING SET DESIGN 1 5 PREFORMED V-RINGS . 2 6 PACKING CHAMBER AND VALVE STEM 3 7 INSPECTION . 4 8 QUALIFICATION TEST . 5 9 RECOMMEN
14、DED INSTALLATION . 5 TABLE 1 V-Ring Sizes . 2 FIGURE 1 Typical Packing Set 2 2 Typical V-Ring . 3 3 Typical Packing Chamber . 4 ANNEX A Referenced Standards and Applicable Dates . 6 MSS STANDARD PRACTICE SP-1491 PREFORMED ELASTOMERIC AND POLYTETRAFLUOROETHYLENE (PTFE) V-RING PACKING SETS FOR WATERWO
15、RKS VALVES 1. SCOPE 1.1 This Standard Practice establishes material, surface finish, dimensional, and testing requirements for preformed V-ring packing sets, packing chambers, and valve stems. 1.2 This Standard Practice applies to homogeneous elastomeric and polytetrafluoroethylene (PTFE) V-ring pac
16、king for gray iron and ductile iron quarter-turn and multi-turn valves for waterworks applications with a maximum service temperature of 150 F (66 C). 2. DEFINITIONS 2.1 Adapters Preformed female and male seal members installed on the top and bottom of the packing set to provide flat ends. 2.2 Cross
17、 Section The nominal width of the chamber or one-half (1/2) of the difference between the outside and inside diameter of the chamber. 2.3 V-Ring A lip type seal member that resembles the letter “V” in the cross section. 2.4 V-Ring Packing Sets A seal assembly consisting of a female adapter, V-rings,
18、 and a male adapter. 2.5 Other definitions may be found in MSS SP-96. 3. V-RING PACKING SET MATERIALS 3.1 Acceptable materials for the packing adapters include, but are not limited to: molded or machined fabric-reinforced rubber, Phenolic Resin, Polytetrafluoroethylene (PTFE), Nylon, Acetal Resin, o
19、r Thermoplastic Elastomers with a hardness factor greater than 80 durometer. NOTE: The adapters shall not contain asbestos; including chrysotile, tremolite, anthophyllte, amosite (grunerite), crocidolite (riebeckite), or actinolite. 3.2 The V-rings shall be constructed of homogeneous natural or synt
20、hetic rubber or polytetrafluoroethylene (PTFE) with a Shore durometer hardness greater than 60. 4. V-RING PACKING SET DESIGN 4.1 The packing set shall be composed of a female top adapter, male bottom adapter, and several V-rings (see Figure 1). The adapters shall conform to the shape and angle of th
21、e packing rings on the inside of the set and provide a flat surface on the top and bottom of the packing set. 4.2 Packing sets shall contain a minimum of two (2) V-rings for pressures up to 250 psig (17.2 bar), three (3) V-rings for pressures up to 500 psig (34.5 bar), and four (4) V-rings for highe
22、r pressures. 4.3 A shim or washer fabricated from the materials listed in Section 3.1 may be used to adjust the height of the packing set. MSS STANDARD PRACTICE SP-1492 FIGURE 1: Typical Packing Set 5. PREFORMED V-RINGS 5.1 Body and Bonnet The V-rings shall form a general “V” shape with flared lips
23、extending past the outside diameter of the packing set, to provide a nominal radial interference (see RI in Figure 2) of 0.015 in. (0.38 mm). The outside angle of the rings shall be formed to make a 90 5 degree included angle, and the inside angle of the rings shall be formed to make a 96 5 degree a
24、ngle as illustrated in Figure 2. A notch may be added to the 96 degree side to facilitate flexing of the packing ring. 5.2 V-rings shall be made to one of the cross sections and corresponding stack heights as shown in Table 1. TABLE 1: V-Ring Sizes Nominal Cross Section in. (mm) Stack Height(1)in. (
25、mm) Nominal Radius (R) in. (mm) 3/16 (4.8) 0.083 (2.11) 1/16 (1.6) 1/4 (6.4) 0.083 (2.11) 1/16 (1.6) 5/16 (7.9) 0.140 (3.56) 7/64 (2.8) 3/8 (9.5) 0.156 (3.96) 1/8 (3.2) 7/16 (11.1) 0.197 (5.00) 5/32 (4.0) 1/2 (12.7) 0.197 (5.00) 5/32 (4.0) NOTE (1): Stack Height Tolerance Reference: 0.010 in. (0.25
26、mm) Stack height may vary by manufacturer. MSS STANDARD PRACTICE SP-1493 FIGURE 2: Typical V-Ring 6. PACKING CHAMBER AND VALVE STEM 6.1 A precision machined chamber shall be provided with an inside diameter and depth as recommended by the packing manufacturer. The recommended depth is the sum of the
27、 nominal stack heights of the component parts, the “plus” tolerances of the components, and the “plus” tolerance of the machined chamber depth (see Figure 3). 6.2 The valve stem shall be provided with an outside diameter and roughness average as recommended by the packing manufacturer. When not spec
28、ified, the roughness shall be an average of 63 Ra microinch (1.6 Ra micrometer) or smoother. 6.3 The surface finish of the chamber that contacts the packing rings shall be 125 Ra microinch (3.18 Ra micrometer) or smoother (see Figure 3). The mating metal surfaces shall be free of scratches, pits, or
29、 voids deeper than 0.002 in. (0.05 mm). 6.4 A 30 degree by 0.06 in. (1.5 mm) minimum chamfer at the stem end and at the chamber opening is recommended to facilitate assembly of the packing set. 6.5 The packing chamber bore and stem bore shall be concentric within 0.004 in. (0.10 mm). MSS STANDARD PR
30、ACTICE SP-1494 FIGURE 3: Typical Packing Chamber 7. INSPECTION 7.1 The packing set shall be free of flashing, cuts, or cracks. 7.2 The height of packing sets shall be measured under a load of 5 lb/in. (0.09 kg/mm) of mean circumference and meet the height and tolerance limits, as specified by the ma
31、nufacturer. 7.3 The inside and outside diameters of the adapters shall be measured and provide diametrical clearance with the packing chamber and stem nominal diameters. 7.4 The inside and outside diameters of the V-rings shall be measured and provide at least 0.005 in. (0.13 mm) of radial interfere
32、nce (RI as shown in Figure 2) with the packing chamber and stem nominal diameters. MSS STANDARD PRACTICE SP-1495 8. QUALIFICATION TEST 8.1 One packing set of each cross section shall be installed in a valve or test fixture with dimensions and finishes that are in accordance with the packing manufact
33、urers recommendations, and with this Standard Practice. 8.2 The packing set shall be hydrostatically tested with 60 80 F (16 27 C) water to 50 psig (3.4 bar) and 250 psig (17.2 bar). Packing sets with pressure ratings above 250 psig (17.2 bar) shall also be hydrostatically tested to their rated pres
34、sure with 60 80 F (16 27 C) water. The test for each packing set shall be conducted for five (5) minutes at each pressure without adjustment in static condition. There shall be no visible leakage during the test. 9. RECOMMENDED INSTALLATION 9.1 Apply a lubricant to the packing, or chamber bore and s
35、tem, which is compatible with the packing material. 9.2 Install the male adapter, V-rings, and female adapter so that the lips face in the direction of the pressurized medium. Use plastic or wood tools for assembly. Avoid using sharp metal tools like screwdrivers. 9.3 On split ring installations or
36、repairs, stagger the cuts in the rings by 90 degrees. 9.4 The packing set should be secured with a mating follower gland or packing plate with a flat surface that supports the female adapter. MSS STANDARD PRACTICE SP-1496 ANNEX A Referenced Standards and Applicable Dates This Annex is an integral pa
37、rt of this Standard Practice and is placed after the main text for convenience. Standard Name Description MSS SP-96-2011 Guidelines on Terminology for Valves and Fittings The following organization appears in the above list. MSS Manufacturers Standardization Society of the Valve and Fittings Industr
38、y 127 Park Street, NE Vienna, VA 22180-4602 Purchase or View a Full Listing of MSS Standards at: http:/msshq.org/Store/PriceList.cfm MSS Standard Practices (SPs) related to or referenced in this publication: ANSI/MSS SP-25 Standard Marking System for Valves, Fittings, Flanges, and Unions ANSI/MSS SP
39、-96 Guidelines on Terminology for Valves and Fittings American National Standards Published by MSS, an ANSI-accredited Standards Developer:ANSI/MSS SP-25 Standard Marking System for Valves, Fittings, Flanges, and Unions ANSI/MSS SP-44 Steel Pipeline Flanges (including 2011 Errata Sheet)ANSI/MSS SP-5
40、5 Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components Visual Method for Evaluation of Surface Irregularities ANSI/MSS SP-58 Pipe Hangers and Supports - Materials, Design, Manufacture, Selection, Application, and Installation ANSI/MSS SP-96 Corrosion Resista
41、nt Pipe Fittings Threaded and Socket Welding Class 150 and 1000ANSI/MSS SP-114 Guidelines on Terminology for Valves and FittingsANSI/MSS SP-134 Valves for Cryogenic Service, including Requirements for Body/Bonnet ExtensionsANSI/MSS SP-138 Quality Standard Practice for Oxygen Cleaning of Valves and F
42、ittings ANSI/MSS SP-144 Pressure Seal Bonnet Valves Do not violate copyright laws All Standard Practices are officially available only from MSS and through our authorized distributors: About MSS The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry is a non-profit techni
43、cal association organized for development and improvement of industry, national and international codes and standards for Valves, Valve Actuators, Valve Modifications, Pipe Fittings, Flanges, Pipe Hangers and Supports, and Associated Seals. Since its establishment in 1924, MSS has been dedicated to
44、developing standards for national and global applications, in cooperation with other standardizing bodies and regulatory authorities. For more information on membership and eligibility requirements, visit: http:/msshq.org/Store/Membership.cfm Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE, Vienna, VA 22180-4620 (703) 281-6613 Fax # (703) 281-6671 “The Technical Voice of the Industry” MSS SP-149-2015
