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1、 MSS SP-88-2010 Diaphragm 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 Phone: (703) 281-6613 Fax: (703) 281-6671 e-mail: infomss-hq.org www.mss-hq.org MSS STANDARD PRAC
2、TICESP-88 i This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 406 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 s
3、pecification that will benefit the industry as a whole. This MSS Standard Practice is intended as a basis for 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 con
4、forming to the Standard Practice. Mandatory conformance is established only by reference in a code, specification, sales contract, or public law, as applicable. “Other standards documents referred to herein are identified by the date of issue that was applicable to this Standard Practice at the date
5、 of issue of this Standard Practice. See Annex B. This Standard Practice shall remain silent on the applicability of those other standards of prior or subsequent dates of issue even though applicable provisions may not have changed. References contained herein which are bibliographic in nature are n
6、oted as supplemental in the text.” 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 Standard Practice (See Annex B). In this Standard Practice all
7、notes, annexes, tables, and figures are construed to be essential to the understanding of the message of the standard, and are considered part of the text unless noted as “supplemental“. All appendices appearing in this document are construed as “supplemental“. Supplemental“ information does not inc
8、lude mandatory requirements. Substantive changes in this 2010 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 edition. U.S. customary units in this Standa
9、rd Practice are the standard; metric (SI) units are for reference only. Any part of this Standard Practice may be quoted. Credit lines should read Extracted from MSS SP-88- 2010 with permission of the publisher, Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Reproduct
10、ion prohibited under copyright convention unless written permission is granted by Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Originally Approved: January 1978 Copyright , 1978, 1983, 1993, 2010 by Manufacturers Standardization Society of the Valve and Fittings Ind
11、ustry, Inc. Printed in U.S.A. MSS STANDARD PRACTICESP-88 ii TABLE OF CONTENTS SECTION PAGE PURPOSE. 1 1 SCOPE. . 1 2 PRESSURE-TEMPERATURE RATINGS. . 1 3 DIAPHRAGMS. . 2 4 BODY-BONNET JOINTS. . 2 5 BODY MATERIALS 3 6 BONNETS 3 7 BODY FACE-TO-FACE DIMENSIONS. 3 8 BODY END CONNECTIONS AND WALL THICKNES
12、S 3 9 ACTUATOR APPLICATION REQUIREMENTS 3 10 SHELL TESTS 4 11 SEAT TESTS 4 12 MARKING 5 TABLE A1 Maximum Service Pressure-Ratings at 100 F (38 C) for Category B Valves (Standard Valves Section 2.2) . 6 A2 Commonly Used Face-To-Face Dimensions of Flanged Diaphragm Valves . 7 A3 Standards Applicable t
13、o Body Wall Thickness and the Dimensions of Threaded, Flanged, and Butt Weld Body End Connections for Category A and Category B Valves Only 8 A4 Body Materials Standards . 9 A5 Test Durations and Test Pressures Based on Diaphragm Maximum Service Pressure Ratings Shown in Table 1 10 ANNEX A Tables 6
14、B Referenced Standards and Applicable Dates . 11 MSS STANDARD PRACTICESP-88 1 PURPOSE The purpose of this Standard Practice is to outline the limitations and requirements of valves in which a nonmetallic, resilient diaphragm is used to separate the working parts of the valve from the line fluid and
15、also functions in conjunction with other parts as valve closure-member. The use of a nonmetallic, resilient diaphragm causes valves described in this Standard Practice to be different from other commonly used valves for which genera1 and specific Standards and Standard Practices are in existence. Th
16、ese differences include pressure-temperature limitations, face-to-face dimension requirements, and specific service characteristics. This Standard Practice reflects industry practice in the design, manufacture, and application of this type of valve. 1. SCOPE 1.1 This Standard Practice applies to val
17、ves for general liquid and gas service that effect valve closure by means of a resilient diaphragm sealing against a weir or a diaphragm acting in conjunction with a separate or integral disk-member sealing against a seat, having equal sealing capability in either flow direction, and having diaphrag
18、ms being essentially made of elastomeric or plastic material or combinations thereof. 1.2 This Standard Practice defines the following categories of valves: a) Class 125 or 150 Valves (See Section 2.1) b) Standard Valves (See Section 2.2) c) Valves for Special (Low Pressure) Applications (See Sectio
19、n 2.3) The purchaser, when referencing the Standard Practice, shall also specify the appropriate category as listed above. 1.3 This Standard Practice covers the following: a) Pressure-Temperature Ratings and Design requirements b) Commonly Used Diaphragm Pressure Limitations c) Body, Bonnet, and Bol
20、ting Materials d) Commonly Used Face-to-Face Dimensions for Flanged Valves e) Body End Connections and Wall Thicknesses f) Actuator Application Requirements g) Tests h) Marking 1.4 For specific requirements relating to the dairy industry, refer to 3-A SSI 54-02. 2. PRESSURE-TEMPERATURE RATINGS 2.1 C
21、ategory A Valves: (Class 125 or 150) The maximum non-shock pressure-temperature ratings of valve bodies for valves in this category shall be those specified in the applicable Standards referenced in Table A3, Annex A, and the valve bodies must conform to the applicable requirements of the referenced
22、 standards (see Sections 2.4 and 2.5 for service ratings of the diaphragms). 2.2 Category B Valves: (Standard Valves) The maximum non-shock pressure-temperature ratings of valves in this category shall be those listed in Table A1, Annex A. Body wall thicknesses shall be those established by the appl
23、icable requirements of the referenced standards in Table A3, Annex A. 2.3 Category C Valves: (Special Valves, Low Pressure) The maximum non-shock pressure-temperature ratings of valves in this category shall be those established by the manufacturer for the particular design. DIAPHRAGM VALVES MSS STA
24、NDARD PRACTICESP-88 2 2.4 The actual service pressure-temperature rating of the assembled diaphragm valves shall be limited to the pressure-temperature rating of the body or the diaphragm, whichever is lower, as outlined in Section 2.5. 2.5 The service ratings of the diaphragms shall be those establ
25、ished by the valve manufacturer for the design and material selection for the intended service. Maximum allowable temperatures for elastomeric, plastic, or combined elastomeric and plastic diaphragms vary with the manufacturers design and the material composition, therefore, standard values cannot r
26、eadily be established. In order to enable the manufacturer to make proper recommendations regarding diaphragm and valve type and material selection, the following conditions shall be provided by the user: a) valve size b) pressure c) temperature d) medium handled, including concentrations of acids o
27、r bases e) mode and/or frequency of operation f) flow rate g) line shock conditions h) vacuum i) use of line cleaning fluids j) submersion of valve. 3. DIAPHRAGMS 3.1 Diaphragm materials shall be as recommended by the valve manufacturer for the intended service, considering the limitations, as outli
28、ned in Section 2.5. 3.2 Diaphragms are dimensionally not interchangeable between the various diaphragm valve designs made by different manufacturers. Replacement diaphragms must be purchased for a specific model of a valve manufacturer to assure the proper dimensional fit. 3.3 Diaphragms determine t
29、he service rating of diaphragm valves in most cases, as outlined in Sections 2.4 and 2.5. Therefore, if a replacement diaphragm is being used that does not show the valve manufacturers name, initials, or easily identifiable trademark, the valve service-ratings established by the valve manufacturer a
30、re invalid. 4. BODY-BONNET JOINTS 4.1 Body-bonnet joint bolting shall be designed to meet the allowable bolting stress specified in ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, at 100F (38C) for the bolting material being used. 4.2 Carbon steel bolts or studs shall meet the minimu
31、m mechanical and the chemical property requirements of ASTM A307, Grade A or B. 4.3 Stainless steel bolts or studs, when specified by the customer, shall meet the minimum mechanical and the chemical property requirements of ASTM A193, Grade B8. 4.4 Alloy steel bolts or studs, when specified by the c
32、ustomer or when required in Category A valves, shall meet the minimum mechanical and the chemical properties requirements of ASTM A193, Grade B7. 4.5 Other corrosion resistant body-bonnet bolt or stud materials or other body-bonnet fastening methods are not covered by this Standard Practice. MSS STA
33、NDARD PRACTICESP-88 3 5. BODY MATERIALS Body materials shall conform to the standards referenced in Table A4, Annex A. Non-listed materials such as special alloys and plastics are not covered by this Standard Practice and are subject to agreement between customer and manufacturer. 6. BONNETS 6.1 The
34、 bonnets of manually operated valves shall be capable of withstanding the hand wheel closure forces and fill-pressure loading in the event of a diaphragm failure. 6.2 The bonnets of valves with actuators must be, in addition to the requirements of Section 6.1, capable of withstanding mechanical stre
35、sses induced by the weight of actuators or any other auxiliary equipment in all possible valve installation positions. 6.3 Except as provided in Sections 6.4 and 6.5, bonnet material shall be cast iron, malleable iron, ductile iron, or cast steel at the manufacturers option, regardless of body mater
36、ials, unless one of these bonnet materials is specified by the customer or a different bonnet material is agreed upon between customer and manufacturer. 6.4 When the customer specifies a pressure- retaining bonnet for Category A valves with body pressure-temperature ratings for Class 125 or 150, the
37、 bonnet shall conform to the wall section and material requirements of the standards listed in Table A3, Annex A. 6.5 Plastic bonnets are permissible when specified by the customer. Plastic bonnets shall be designed and qualified in accordance with ASME B31.3, paragraph A304.7. 6.6 The seal of the s
38、ealed bonnets, when specified by the customer, shall be designed to contain line pressure or vacuum in the event of diaphragm failure. 7. BODY FACE-TO-FACE DIMENSIONS Face-to-face dimensions of flanged diaphragm valves and valve centerline-to-top dimensions are peculiar to the particular manufacture
39、rs design. Consult each manufacturer for specific dimensions. Commonly used face-to-face dimensions of flanged diaphragm valves are given in Table A2, Annex A, for the guidance of diaphragm valve users. 8. BODY END CONNECTIONS AND WALL THICKNESS 8.1 Body end connections shall conform to the standard
40、s referenced in Table A3, Annex A. 8.2 Body wall thicknesses of Category A and B valves, shall conform to the standards referenced in Table A3, Annex A, for Classes 125 and 150. 8.3 Body wall thicknesses of Category C valves specifically designed and marked for pressure ratings lower than those spec
41、ified in Sections 2.1 and 2.2 shall be the manufacturers standard. 9. ACTUATOR APPLICATION REQUIREMENTS 9.1 Manually operated valves shall be actuated by handwheels or quick-opening levers with counter clockwise rotation to open the valve. Different means of manual actuation can be specified after a
42、greement between customer and manufacturer. 9.2 Handwheels shall be of sufficient diameter to ensure tight, manual closure at the specified service pressure of the valve. 9.3 Handwheels shall be marked with the direction of movement for opening the valve. MSS STANDARD PRACTICESP-88 4 9.4 Pneumatic,
43、hydraulic, pneumatic spring return, hydraulic spring return, or electric actuators shall be sized to be capable of closing the valve against a minimum of 1.1 times the maximum service pressure rating of the valve. In case the actual shutoff pressure specified by the customer is lower than the maximu
44、m service pressure rating of the valve, the actuator may be sized to be capable to close against a minimum of 1.1 times the actual shutoff pressure with the customers approval.(1) 9.5 Available air or hydraulic pressure or electric current data must be specified by the customer. 10. SHELL TESTS 10.1
45、 Each Category A Class 125 or 150 diaphragm valve body shall be hydrostatically tested at 1.5 times maximum working pressure specified in the applicable Standard referenced in Table A3, Annex A. Each Category A Class 125 or 150 diaphragm valve bonnet shall be hydrostatically tested with the same pre
46、ssure as the valve body, when specified by the customer, and may be tested simultaneously with the body by using a gasket in place of a diaphragm. 10.2 Each Category B diaphragm valve having a service pressure established in accordance with Section 2.2 shall receive a hydrostatic or air shell test i
47、n accordance with Table A5, Annex A, with the valve in the full open position. Each bonnet for Category B valves shall be hydrostatically tested with the same pressure as the valve body, when sealed bonnet and testing is specified by the customer. Bonnet test method shall be at the option of the man
48、ufacturer. Supplementary Information (1) CAUTION: A diaphragm valve displaces fluid during the closing movement of the diaphragm; therefore, the valve cannot be closed against liquid in a pipe with two closed valves in close proximity, one upstream and one downstream. Excessive actuator force can da
49、mage the diaphragms by increasing fluid pressure beyond the capabilities of the diaphragm if the valve is forced to close against such conditions by an oversized actuator. 10.3 Each Category C diaphragm valve having a design pressure-temperature rating established in accordance with Section 2.3 shall receive a hydrostatic or air shell test with a minimum test pressure of 1.2 times the design pressure- temperature rating, with the valve in the full open position. Each bonnet for Category C