MSS SP-130-2013 Bellows Seals for Instrument Valves.pdf

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1、 MSS SP-130-2013 Bellows Seals for Instrument 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: (703) 281-6613 Fax: (703) 281-6671 E-mail: standardsmss-hq.org MS

2、S www.mss-hq.org MSS STANDARD PRACTICE SP-130 This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 115 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide an effec

3、tive, 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 not in its

4、elf 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, nor does

5、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 indicated otherw

6、ise 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 validity of t

7、hose 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 not be

8、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 construed to be

9、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 requirements. U.S.

10、customary units in this Standard Practice are the standard; the SI (metric) units are for reference only. Substantive changes in this 2013 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 f

11、lagged with that in the previous edition. Non-toleranced dimensions in this Standard Practice are nominal unless otherwise specified. Excerpts of this Standard Practice may be quoted with permission. Credit lines should read Extracted from MSS SP-130-2013 with permission of the publisher, Manufactur

12、ers 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 Fittings Industry Inc. All rights r

13、eserved. Originally Approved: September 2003 Originally Published: November 2003 Current Version Approved: May 2013 Current Version Published: May 2013 MSS is a registered trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright , 2013 by Manufacturers St

14、andardization Society of the Valve and Fittings Industry, Inc. Printed in U.S.A. i MSS STANDARD PRACTICE SP-130 TABLE OF CONTENTS SECTION PAGE 1 SCOPE 1 2 DESIGN 1 3 INSPECTION AND TEST . 3 4 SHIPPING INFORMATION 4 5 ORDERING INFORMATION . 4 TABLE 1 Bellows Cycle-Life Categories 2 2 Bellows Leak-Rat

15、e Categories 4 FIGURE 1 Typical Bellows Assembly . 3 ANNEX A Definitions . 5 B Referenced Standards and Applicable Dates . 6 ii MSS STANDARD PRACTICE SP-130 1. SCOPE 1.1 This Standard Practice provides requirements for design, materials, fabrication, installation, qualification, examination, testing

16、, and shipment of convoluted metal bellows or bellows assemblies to be installed in linear, actuated valves and manifolds. It covers steel and alloy valves of NPS 1 and smaller and pressure ratings of 10,000 psi (70 MPa) and lower at 100 F (38 C). This Standard Practice is not intended to define or

17、limit designs, construction, performance, envelope dimensions, or valve types. 1.2 The application of valve type, size, rating, materials of construction, and suitability for the service is the responsibility of the purchaser and is outside the scope of this Standard Practice. 1.3 The manufacturer s

18、hall provide pressure ratings for temperatures above 100 F (38 C). This temperature is the temperature of the pressure-containing shell of the component. In general the temperature is the same as that of the contained fluid. Use of a pressure rating corresponding to a temperature other than that of

19、the contained fluid is the responsibility of the user, subject to the requirements of applicable codes and regulations. 2. DESIGN 2.1 General 2.1.1 The purpose of the bellows seal is to provide a metal barrier between the stem at its point of entry through the pressure boundary and the process fluid

20、 within the valve to reduce stem leakage to nearly undetectable limits. The bellows seal shall be designed to act as a pressure seal equivalent to conventional pressure boundary components such as packings or O-rings. 2.1.2 Except as specifically noted herein, the rules governing the design of all o

21、ther valve components found in the parent-valve specification shall apply to the bellows seal assembly. 2.2 Pressure-Temperature Ratings 2.2.1 Bellows seals shall comply with the same pressure-temperature requirements as those listed for valves in ASME B16.34, ASME B31.1, ASME B31.3, MSS SP-99, MSS

22、SP-105, or other parent specifications. The bellows shall cycle satisfactorily at the parent valve 100 F (38 C) rating. The valve manufacturer shall have the option to de-rate the bellows seal to some lower pressure scheme at elevated temperature than the pressure-temperature rating of the parent va

23、lve. The manufacturer shall have the option to apply an elevated temperature limit due to the bellows limitations. The valve manufacturer shall provide published ratings when a de-rated pressure-temperature scheme for the bellows applies. 2.3 Materials 2.3.1 Acceptable bellows materials are: a) Stai

24、nless Steel Types 321, 316, 316L: ASTM A240 and A312/A312M b) Stainless Steel Types 304 and 304L: ASTM A240 and A312/A312M c) Stainless Steel Type 347: ASTM A240 and A312/A312M d) Alloy 600: ASTM B168 and B167 e) Alloy 625: ASTM B443 f) Alloy 718: ASTM B670 g) Alloy 400: ASTM B127 and B165 h) Alloy

25、C22: ASTM B575 and B622 i) Alloy C276: ASTM B575 and B622 NOTE: Other materials than those listed above are acceptable for use as agreed upon by the manufacturer and user. BELLOW SEALS FOR INSTRUMENT VALVES 1 MSS STANDARD PRACTICE SP-130 2.3.2 Acceptable materials for the bellows end attachment, inc

26、luding rings, caps or flanges (if utilized) are: a) Stainless Steel Types 321, 316, and 316L: ASTM A276 and A479/A479M b) Stainless Steel Types 304 and 304L: ASTM A276 and A479/A479M c) Stainless Steel Type 347: ASTM A276 and A479/A479M d) Alloy 600: ASTM B564 e) Alloy 625: ASTM B446 f) Alloy 718: A

27、STM B637 g) Alloy 400: ASTM B164 and B564 h) Alloy C22: ASTM B574 i) Alloy C276: ASTM B574 NOTE: Other materials than those listed above are acceptable for use as agreed upon by the manufacturer and user. 2.3.3 The bellows, bellows end attachment, and stem-attachment point shall be weld compatible a

28、nd have no negative effect on the bellows corrosion resistance. 2.4 Bellows Fabrication 2.4.1 A bellows may be constructed by forming convolutions on butt welded tube or drawn tube. Forming of convolutions may be accomplished either mechanically or hydraulically, or by any other suitable manufacturi

29、ng method. 2.4.2 Tube may be single or multi-ply. Butt welds on multi-ply bellows shall be equally spaced (180 for two-ply or 120 for three-ply). Precautions shall be taken in the fabrication of multi-ply bellows to prevent moisture or other contamination between the plies. 2.4.3 Appropriate design

30、features shall be included to prevent distortion of the bellows and to prevent localized contact between the bellows convolutions, valve body or stem, or both. 2.5 Stem Connection 2.5.1 Torsional loads to the bellows shall be minimized or prevented. 2.5.2 The bellows or an intermediate component wel

31、ded to the end of the bellows at the moving end shall be attached to the stem by welding. A mechanical connection between the stem and the bellows is not permitted. 2.6 Fixed Connection 2.6.1 The bellows fixed end shall be welded to the body, to the bonnet, or to a flange clamped or welded between t

32、he body and the bonnet. A mechanical connection to the bellows is not permitted. 2.7 Bellows Axial Movement 2.7.1 Appropriate stops shall be included in the valve design by the valve manufacturer to prevent compression or extension of the bellows beyond that qualified by the cycle-life test. 2.8 Bel

33、lows Cycle-Life 2.8.1 A cycle is defined as fully opened, to fully closed, to fully open. The bellows design shall be qualification tested in accordance with the following table, unless otherwise specified by the valve manufacturer and user. TABLE 1 Bellows Cycle-Life Categories Category Minimum Cyc

34、le-Life A 2,000 B 5,000 C 25,000 D 100,000 E 1,000,000 2.8.2 The suitability of the bellows assembly design shall be demonstrated by means of prototype testing upon representative samples, as qualified per Section 3.1. See Figure 1 for an illustration of a typical bellows assembly. 2 MSS STANDARD PR

35、ACTICE SP-130 FIGURE 1 Typical Bellows Assembly 2.9 Bellows Welding 2.9.1 All welding of the bellows and bellows attachments shall be performed by qualified operators using qualified procedures. All welding qualifications shall be per ASME Boiler and Pressure Vessel Code, Section IX or ASME B31.3, C

36、hapter X. 2.9.2 Bellows welds and bellows attachment welds, if not attached directly to the valve body or bonnet, are excluded from heat treatment requirements of the parent specifications. Heat treatment may have a detrimental effect on the cycle life of the bellows. 2.9.3 The bellows material shal

37、l be free of weld repair. 3. INSPECTION AND TEST 3.1 Bellows Design Qualification-Testing 3.1.1 The bellows assembly shall be cycle-life tested in an assembled valve at rated operating pressure and ambient temperature. 3.1.2 Any variation that constitutes a change in basic design parameters that aff

38、ects cycle life of the bellows shall require re-qualification by cycle testing (e.g., change in stroke, bellows supplier, material specification, number of plies, wall thickness, or dimensions. A change in overall length or number of convolutions may not require requalification provided that the per

39、centage of bellows movement in both compression and extension is the same or less than that of originally qualified bellows where: Mc= (L1 Lc) x 100 / L1Me= (Le L1) x 100 / L1Where: Mc = the percent of movement in compression L1 = the live length Lc = the compressed length Me = the percent of moveme

40、nt in extension Le = the extended length 3.1.3 After welding a bellows to stem and fixed connections and prior to qualification testing, each bellows assembly shall be outboard helium leak-tested and shall not exceed 10-4cc/sec He or as permitted by the parent valve specification. 3.1.4 Prior to cyc

41、le testing, each bellows assembly shall be hydrostatically pressure tested at 1.5 times the 100 F (38 C) valve design-pressure. Each bellows assembly shall be fixed at the length where the valve is in the opened position as required in normal valve shell tests. Water used for testing of stainless st

42、eel bellows assemblies shall contain less than 100 ppm chlorides. No visible leakage permitted. 3.1.5 Valves incorporating stem packings shall have the packing removed for purposes of the cycle life/leakage testing. If packings must be left in place, the leakage measurements shall be taken from a te

43、st port on the pressure side of the packing. 3.1.6 The frequency of cycling shall take into consideration excessive heat that can be generated by abnormally fast cycling. 3 MSS STANDARD PRACTICE SP-130 3.1.7 Cycling shall be carried out at ambient temperature and at the 100 F (38 C) rated pressure o

44、f the bellows. The pressure shall be applied in a manner to simulate normal valve shell tests (see Table 1). 3.1.8 A minimum of seven bellows of each basic design and material selected at random from those produced using the typical production manufacturing processes shall be cycled to achieve the a

45、ppropriate minimum cycle-life requirement designated in Section 2.8.1. This will give a reliability of 90% with a 50% confidence level. 3.1.9 After completing the life-cycle tests, each bellows shall be outboard leak tested and exhibit no detectable leakage. Leak testing can be air-under-water at a

46、minimum of 80 psig (5.5 kPa), or by an instrument with a sensitivity of 10-6cc/sec He used in the sniffer mode and not exceeding 10-4cc/sec He, or as permitted by the parent valve specification. 3.1.10 For valves tested to comply with the Clean Air Act Fugitive Emissions Limitations, the leakage dat

47、a shall be shown as methane equivalent ppm. Background leakage shall be recorded prior to testing valves per Table 2. TABLE 2 Bellows Leak-Rate Categories Class Allowable Leakage in PPM CH4A 100 PPM B 500 PPM 3.1.11 Cycle-life testing data shall be documented and available. 3.2 Production Testing 3.

48、2.1 Bellows and bellows assemblies shall be leak tested by a suitable method and exhibit no detectable leakage. 4. SHIPPING INFORMATION 4.1 Each bellows assembly shall be cleaned, dried, and packaged to prevent moisture or contamination damage. 4.2 Each bellows assembly shall be individually package

49、d to minimize damage during handling or in transit. 4.3 Each bellows assembly, if practical, shall be marked to insure proper identification of the material. If it is impractical to mark each assembly, each package shall be so marked. 4.4 Material certification of conformance for the bellows and end attachments is required to be furnished by the bellows manufacturer for each shipment. 5. ORDERING INFORMATION 5.1 If the valve manufacturer needs a bellows seal that deviates from this Standard Practice, it is the valve manufacturers responsibility to clearly define s