1、 MSS SP-68-2011 High Pressure Butterfly 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 22180-4602 Phone: (703) 281-6613 Fax: (703) 281-6671 E-mail: infomss-h
2、q.org MSS www.mss-hq.org MSS STANDARD PRACTICE SP-68i This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 407 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide
3、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. The existence of an MSS Standard Practice does no
4、t 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, or public law, as applicable. MSS has no power, n
5、or 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 certifier or maker of the statement. “Unless indicate
6、d 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 B). This Standard Practice shall remain silent on the valid
7、ity 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 any patent rights in connection therewith. MSS shall
8、 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, annexes, tables, figures, and references are construe
9、d 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 information does not include mandatory requirement
10、s. U.S. customary units in this Standard Practice are the standard; (SI) metric units are for reference only. Substantive changes in this 2011 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 materi
11、al flagged with that in the previous edition. Non-toleranced dimensions in this Standard Practice are nominal, and, unless otherwise specified, shall be considered “for reference only”. Excerpts of this Standard Practice may be quoted with permission. Credit lines should read Extracted from MSS SP-6
12、8-2011 with permission 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 o
13、f the Valve and Fittings Industry Inc. All rights reserved. Originally Published: October 1984 Current Edition Approved: February 2011 Current Edition Published: October 2011 MSS is a registered trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright , 2
14、011 by Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Printed in U.S.A. MSS STANDARD PRACTICE SP-68ii TABLE OF CONTENTS SECTION PAGE 1 SCOPE . 1 2 DESIGN REQUIREMENTS . 1 3 FACE-TO-FACE DIMENSIONS 2 4 MARKING 3 5 DESIGN . 3 TABLE 1 Face-to-Face Dimensions, NPS 3 to 24
15、 . 2 2 Face-to-Face Dimensions, NPS 30 to 48 . 2 3 Shell Test Duration 3 4 Seat Test Duration 3 A1 Disc-to-Pipe Minimum Nominal Radial Clearances 5 FIGURE A1 Nomenclature and Explanation of Nominal Radial Clearance . 5 ANNEX A Disc-to-Pipe Clearance . 5 B Referenced Standards and Applicable Dates 6
16、MSS STANDARD PRACTICE SP-681 1. SCOPE 1.1 This Standard Practice covers design requirements, test performance, marking requirements, and nomenclature for butterfly valves designed for high pressure performance, having a seat plane offset from the plane of the stem centerline. 1.2 This Standard Pract
17、ice covers flangeless (wafer-type) and single flanged (lug-type) body designs, compatible with ASME B16.5 flanges for sizes NPS 3 (DN 80) through NPS 24 (DN 600) and ASME B16.47 Series A flanges for sizes NPS 30 (DN 750) through NPS 48 (DN 1200). Reference Tables 1 and 2. 1.3 This Standard Practice
18、covers valves having body pressure temperature ratings in accordance with ASME B16.34. 1.4 Definitions may be found in MSS SP-96. 2. DESIGN REQUIREMENTS 2.1 Valve Flange Gasket Surfaces The flange gasket surfaces of the valve body (against the mating flanges) shall be flush with or raised from other
19、 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 1.0 times the nominal bolt diameter. 2.2.2 Unless otherwise specified by the customer, threaded hole
20、s for flange bolting shall be tapped in accordance with ASME B1.1 Coarse Thread Series Class 2B for bolts 1 in. and smaller and shall be tapped to the 8-Thread Series Class 2B for bolts 118in. and larger. 2.3 Minimum Disc-to-Pipe Clearance 2.3.1 The valve disc will upon rotation project beyond the b
21、ody flange gasket surfaces and therefore 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 piping, strainers, check valves and other valve related components. Also mating pipe flanges should be carefu
22、lly 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 50); and with Schedule 80 pipe for the NPS 3 (DN 80) through NPS 6 (DN 150
23、) sizes; and Schedule 100 for NPS 8 (DN 200) through NPS 24 (DN 600) sizes of Class 600 (PN 100). 2.3.3 All valves shall be designed for disc-to-pipe clearance according to the requirements of Annex A. 2.3.4 When the user elects to use a heavier schedule pipe than listed in Section 2.3.2, it shall b
24、e his responsibility to insure disc-to-pipe clearance. 2.4 Minimum Wall Sections All valves shall have a minimum wall thickness as required by ASME B16.34 for the rating marked on the identification plate. 2.5 Special Requirements for Single Flange (Lug-Type) Valves Single flange (lug-type) valves m
25、ay be designed for closure in dead-end piping when installed against a single flange. Such condition may also occur after removing the companion flange and piping from one side of the valve. Single flange (lug-type) valves which have every flange bolt hole threaded shall be designed such that all pa
26、rts which are necessary to support pressure loads acting across the seating element safely HIGH PRESSURE BUTTERFLY VALVES WITH OFFSET DESIGN MSS STANDARD PRACTICE SP-682 support the maximum differential pressure rating of the valve. Examples of such parts are seat seal retaining plates and their bol
27、ting or retaining means. In the event that the valve design cannot accommodate these 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
28、that the components cannot be assembled to falsely indicate the open or closed position of the valve. 2.7 Stems Stem retention and strength shall meet the requirements of ASME B16.34. The design shall not rely on actuation components (e.g., gear operators, actuators, levers, etc.) to prevent ejectio
29、n. 2.8 Retention by Stem Seal Element Valves shall be designed so that the stem seal retaining fasteners (e.g., packing gland fasteners) alone do not retain the stem. Specifically, the design shall be such that the stem shall not be capable of removal from the valve while the valve is under pressure
30、 by the removal of the stem seal retainer (e.g., gland) alone. 2.9 Retention by Closure Member Valves, including those intended for isolation, regulation, or flow reversal shall be provided with a means so that in the event of a structural failure of stem-to-closure attachment items, the stem will n
31、ot be ejected through the pressure boundary while the valve is under pressure. 3. 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
32、1. TABLE 1 Face-to-Face Dimensions, NPS 3 to 24(a) Valve Size Class 150 (PN 20) Class 300 (PN 50) Class 600 (PN 100) NPS DN in. mm in. mm in. mm3 80 1.88 48 1.88 48 2.12 54 4 100 2.12 54 2.12 54 2.50 64 6 150 2.25 57 2.31 59 3.06 78 8 200 2.50 63 2.88 73 4.00 102 10 250 2.81 71 3.25 83 4.62 117 12 3
33、00 3.19 81 3.62 92 5.50 140 14 350 3.62 92 4.62 117 6.12 155 16 400 4.00 101 5.25 133 7.00 178 18 450 4.50 114 5.88 149 7.88 200 20 500 5.00 127 6.25 159 8.50 216 24 600 6.06 154 7.12 181 9.13 232 Note: (a) Tolerance/variance not to exceed .13 in. (3.5 mm). 3.2 Valve body face-to-face dimensions for
34、 sizes NPS 30 (DN 750) through NPS 48 (DN 1200) Class 150 (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; ISO 5752 Series 20 for Type 2;
35、 and ISO 5752 Series 16 for Type 3. TABLE 2 Face-to-Face Dimensions, NPS 30 to 48(b) Valve Size Type 1 Type 2 Type 3 NPS DN in. mm in. mm in. mm30 36 42 48 750 900 1100 1200 6.50 7.88 9.68 10.88 165 200 246 276 7.50 8.00 9.00 10.00 191 203 229 254 9.05 9.50 11.81 13.78 230 241 300 350 Note: (b) Tole
36、rance/variance not to exceed .25 in. (6.4 mm). MSS STANDARD PRACTICE SP-683 4. MARKING 4.1 Valves shall be marked in 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
37、 on the permanently affixed identification plate. 4.2 Valves designated for shutoff in a required direction (one-way valves) shall be clearly and permanently marked to identify the high pressure side or direction of flow. 4.3 Valves conforming to the requirements of this Standard Practice may be mar
38、ked SP-68 on the identification plate. 5. TESTING 5.1 Shell Test Each valve shall be given a shell test at a gage pressure no less than 1.5 times the 100 F (38 C) rating, rounded off the next higher 25 psi (1 bar) increment. The test shall be made with water, which may contain a corrosion inhibitor,
39、 or with kerosene, or with other suitable fluid (liquid or gas), provided such fluid has viscosity not greater than that of water, at a temperature not above 125 F (52 C). Visually detectable leakage through pressure boundary walls is not acceptable. Test duration shall not be less than shown in Tab
40、le 3. TABLE 3 Shell Test Duration Valve Size Shell Test Duration (Seconds, Minimum) NPS DN 3 8 10 18 20 48 80 200 250 450 500 1200 30 60 120 The test shall be made with the valve in the partially open position. Leakage through the stem packing shall not be cause for rejection if the manufacturer can
41、 demonstrate that the shaft seal design is capable of sealing at 1.1 times the maximum rated pressure of the valve. 5.2 Seat Testing 5.2.1 Each valve shall be tested in accordance with Section 5.2.2, 5.2.3, or 5.2.4, as appropriate. For bidirectional valves, the test pressure shall be applied across
42、 the disc in the direction producing the most adverse seating condition. Valves limited to closure against differential pressure in one direction (see Section 4.2) shall be tested in that direction. 5.2.2 Each valve furnished for shutoff or isolation service shall be subjected to a seat test using f
43、luid as described in Section 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 allowed. Test duration shall not be less than shown in Table 4. TABLE 4 Seat Test Duration 5.2.3 Each
44、valve furnished for shutoff or isolation applications, where seat leakage is permissible, shall be tested as specified in Section 5.2.2, except that leakage past the seal shall not exceed the maximum leakage allowance specified by the purchaser. 5.2.4 Each valve furnished for services other than shu
45、toff or isolation shall be tested at a pressure and with seat leakage allowance as agreed upon by manufacturer and purchaser. Valve Size Seat Test Duration (Seconds, Minimum) NPS DN 3 8 10 18 20 48 80 200 250 450 500 1200 30 60 120 MSS STANDARD PRACTICE SP-684 5.2.5 Leakage detection devices (e.g.,
46、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 Sections 5.1 and 5.2. When used, the valve manufacturer shall have demonstrated that the test results are equivalent to the requirements of Sections 5.1
47、and 5.2.6. 5.2.6 For automatic leak detection methods, the term “no visible leakage“ refers to a leakage rate of no greater than 5 x 10-6in3/sec (8 x 10-7ml/sec) per valve NPS(1). Test duration shall be as shown in Section 5.2.2. NOTE: The footnote below is for supplementary purposes only and is not
48、 a normative part of this Standard Practice. (1) This leakage rate is based on the measured leakage of nitrogen gas from a needle valve with a 0.167 in. O.D. x 0.091 in. I.D. (4.242 mm O.D. x 2.311 mm I.D.) tube discharge submerged in water to a depth of 1 inch (25.4 mm). The tube end was cut square
49、 and smooth with no chamfers or burrs and the tube 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 this data, a leak rate equivalent to 1 bubble every minute is found to be 4.1 x 10-5in3/sec (6.7 x 10-4ml/sec). MSS STANDARD PRACTICE SP-685 ANNEX A Disc-to-Pipe Clearance In accordance with Sections 2.3.2 and 2.3.3 of this Standard Practice, butterfly valves shall be designed to have clearance with the inside diam
