1、 MSS SP-78-2011 Gray Iron Plug Valves, Flanged and Threaded Ends 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-hq
2、.org www.mss-hq.org MSS MSS STANDARD PRACTICE SP-78i This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 106 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide a
3、n 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 not
4、 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, no
5、r 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 indicated
6、 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 C). This Standard Practice shall remain silent on the validi
7、ty 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 construed
9、 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 requirements
10、. 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 materia
11、l 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-78
12、-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 of
13、 the Valve and Fittings Industry Inc. All rights reserved. Originally Approved: September 1972 Originally Published: November 1972 Current Edition Approved: August 2010 Current Edition Published: October 2011 MSS is a registered trademark of the Manufacturers Standardization Society of the Valve and
14、 Fittings Industry, Inc. Copyright , 2011 by Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Printed in U.S.A. MSS STANDARD PRACTICE SP-78ii FOREWORD The 1998 edition of MSS SP-78, in addition to various editorial changes, includes changes to: 1) provide a more complet
15、e metric version for reference use; 2) delete the Class 800 Pressure-Temperature rating; and 3) expand Annex C to include ISO references. The 2005 edition of MSS SP-78 includes the following: 1) added minimum wall requirements that were previously omitted; 2) replaced the terminology “cast” iron wit
16、h “gray” iron in order to specifically identify the required valve material; 3) deleted CWP 400 since the scope of this Standard Practice is Class 125 and Class 250 valves; 4) deleted the PN and DN designations since these are not SI units and easily confused with designations used in international
17、standards that were based on other material specifications and pressure-temperature rating procedures; 5) deleted ISO references as a result of change 4 above. The 2005a edition of MSS SP-78 was issued to correct errors in the ASTM specification numbers and titles listed in Annex C. This 2011 editio
18、n of MSS SP-78, in addition to various editorial and formatting updates, includes changes to: (1) revise Table 2 by including DN designations and adding data for NPS 20 (DN 500) and larger values; (2) update the organizations and references in Annex C; and (3) revise and/or include SI (metric) infor
19、mation for Section 5.1and Table B1. MSS STANDARD PRACTICE SP-78iii TABLE OF CONTENTS SECTION PAGE 1 SCOPE . 1 2 VALVE DESIGNATION, CLASSES, AND SIZES . 1 3 MATERIALS . 1 4 DESIGN . 2 5 PRESSURE-TEMPERATURE RATINGS . 4 6 WORKMANSHIP . 4 7 TESTS 4 8 MARKING 4 9 PREPARATION FOR SHIPMENT 4 TABLE 1 Press
20、ure-Temperature Ratings, Non-Shock, psi 2 2 Test Duration, Minimum . 4 B1 Pressure-Temperature Ratings, Non-Shock, bar 7 FIGURE A1 Single Gland Plug Valve 5 A2 Regular Gland Plug Valve . 5 A3 Threaded Gland Plug Valve . 6 A4 Cylindrical Plug Valve . 6 ANNEX A Valve Types Figures A1 through A4 . 5 B
21、SI (Metric) Units 7 C Referenced Standards and Applicable Dates . 8 MSS STANDARD PRACTICE SP-781 1. SCOPE 1.1 This Standard Practice covers gray iron plug valves with flanged or threaded ends. 1.2 This Standard Practice covers valves in sizes and pressure-temperature ratings specified herein for gen
22、eral purpose service. 1.3 This Standard Practice also includes, directly or by reference, stipulations on chemical and mechanical properties of materials and on dimensions of end connections in common use. 2. VALVE DESIGNATION, CLASSES, AND SIZES 2.1 Valve Types Valve types covered by this Standard
23、Practice are as follows: Type I Single Gland (2-Bolt Bonnet) (See Figure A1) (1)Type II Regular Gland (Bolted Gland) (See Figure A2) (1)Type III Threaded Gland (See Figure A3) (1)Type IV Cylindrical (See Figure A4) (1)2.2 Patterns Valve patterns covered herein are classified in three general design
24、groups as follows: regular pattern, short pattern, and venture pattern. 2.3 Pressure Classes Flanged end valves covered by this Standard Practice are identified by Class numbers for mating ASME B16.1 flanges designated as: Class 125 Class 250 Note: (1) The figures shown in Annex A are for the purpos
25、e of illustration and parts nomenclature only. They are not intended to exclude any design meeting this Standard Practice. The valves may be either of the lubricated or non-lubricated type. Only one of many types of non-lubricated valves is shown in Figure A3. Threaded end valves covered by this Sta
26、ndard Practice are identified by Class numbers corresponding to flanged valves. 2.4 Sizes a) Flanged end valve in sizes 2 NPS 24 b) Threaded end valves in sizes 2 NPS 6 3. MATERIALS 3.1 General The requirements prescribed in this Standard Practice are based upon the use of materials of high quality
27、produced under regular control of chemical and physical properties by a recognized process. The manufacturer shall be prepared to certify, at the time of shipment from his works, that his product has been so produced and that the chemical and physical properties thereof, as proven by test specimens,
28、 are at least equal to the requirements shown in the specifications referenced in this document. NOTE: Users are cautioned against applications which may react chemically with any materials used in these valves. Consultation with the manufacturer is advised to determine suitability in cases of doubt
29、. 3.2 Bodies and Plugs Bodies shall be made from Gray Iron Castings, ASTM A126, Class B. Plugs may be made from the following materials: Gray Iron Castings, ASTM A126, Class B; Gray Iron Castings, ASTM A48/A48M, Class 40; Composition Bronze, ASTM B62, or ASTM B584, UNS C83600. 3.3 Seating Material B
30、earing surfaces and seating materials shall be selected and/or processed so as to minimize the possibility of galling in sliding contact, and to resist wear, corrosion, and erosion within the rated temperature ranges. Hardfacing applied by welding or brazing shall not be used. 3.4 Cover and Bonnets
31、Covers and bonnets shall be made from Gray Iron Castings, ASTM A126, Class B. GRAY IRON PLUG VALVES, FLANGED AND THREADED ENDS MSS STANDARD PRACTICE SP-782 3.5 Operating Mechanisms Wrenches, handwheels and chains wrenches, unless otherwise specified by the purchase order, shall be of ductile iron, m
32、alleable iron, or steel. If a chainwheel is provided, the chainwheel shall be steel. 3.6 Bolting Bolts and studs connecting pressure containing parts shall develop physical strength not less than requirements of ASTM A307, Grade B over the temperature range for which the valve is rated. 4. DESIGN 4.
33、1 General 4.1.1 Valves shall be of design adequate to prevent permanent deformation under the test pressure loadings specified in Section 7. Consideration should be given to the need for adequate metal thickness for assembly, closing stresses, shapes other than circular, and stress concentrations, i
34、n addition to pressure containment requirements. The minimum thickness of the cover or bonnet shall be at least equal to the minimum thickness of the body. 4.1.2 Valve bodies and bonnets shall meet the minimum wall thickness requirements specified in ASME B16.1 for the same NPS and Class gray iron f
35、itting. 4.1.3 Valve bodies shall be designed to provide a maximum streamline flow condition through the valve. 4.2 End Flanges 4.2.1 End flanges shall be integral with the valve body. Flange facings and drilling shall conform to ASME B16.1 for each respective pressure class and size. 4.2.2 The flang
36、es shall be finished on the joint side in accordance with MSS SP-6. 4.2.3 Face-to-face dimensions of flanged end valves shall conform to ASME B16.10. 4.3 Threaded Ends Valve ends shall be threaded with taper pipe threads that conform to ASME B1.20.1. 4.4 Bolting 4.4.1 Dimensions of bolts and cap scr
37、ews shall conform to ASME B18.2.1. Nut dimensions shall conform to ASME B18.2.2. 4.4.2 Threading shall conform to ASME B1.1. Nominal diameters 1 inch and smaller TABLE 1 Pressure-Temperature Ratings, Non-Shock, psi Temperature (F) CLASS 125 CLASS 250 NPS 2 12 NPS 14 24 NPS 30 48 NPS 2 12 NPS 14 24 -
38、20 to 150 200 150 150 500 300 200 190 135 115 460 280 225 180 130 100 440 270 250 175 125 85 415 260 275 170 120 65 395 250 300 165 110 50 375 240 325 155 105 355 230 350 150 100 335 220 375 145 315 210 400 140 290 200 425 130 270 450 125 250 Note: See Table B1 for SI (metric) units. MSS STANDARD PR
39、ACTICE SP-783 shall be of the Course-Thread Series; nominal diameters 118inch and larger shall be of the 8-Thread Series or of the Coarse-Thread Series. Bolts, studs, and stud bolts shall have Class 2A dimensions, and nuts shall have Class 2B dimensions. 4.5 Stem and Plug The stem may be integral wi
40、th the plug or separate from it. In either case, the stem or connection between the stem and plug, shall be of a design adequate to prevent permanent distortion under the maximum torque specified by the manufacturer. 4.6 Gland 4.6.1 Stem glands, where used, may be of either screwed, bolted solid, or
41、 bolted two-piece self-aligning type. 4.6.2 Gland bolts shall pass through holes in the gland; the use of open slots is not permissible in either body or gland. 4.7 Stem Retention Valves having stems not integral with plugs shall be designed so that the stem retaining fasteners, e.g., gland fastener
42、s, alone do not retain the stem. Specifically, in valves having separate stems the design shall be such that the stem shall not be capable of removal from the valve by the removal of the stem seal retainer alone. 4.8 Operation 4.8.1 Plug valves shall be designed for operation by a wrench or handwhee
43、l that turns counter-clockwise to open. Suitable means shall be provided to indicate the direction of opening the valve and the position of the plug. Provision shall be made for stops to limit the movement of the plug at the open and closed positions. 4.8.2 A wrench may be of integral design or cons
44、ist of a head fitted onto the operating shaft and be provided with a socket or other suitable means to take an extended handle. The wrench head shall be capable of being secured to the shaft with a set screw or other suitable means. When not integral, a wrench shall be furnished only when specified
45、in the purchase order. 4.8.3 When specified in the purchase order, a handwheel shall be furnished with each gear operated valve. Handwheels shall be of spoked design. Webbed or disc handwheels shall not be used. Spokes extending beyond the wheel ring (tiller type) are permissible. 4.8.4 Valves desig
46、ned to accommodate a device for locking the plug assembly in either the open or closed position shall be furnished when specified by the purchase order. 4.9 Bypass and Drain Connections When specified by the purchaser, bypass and drain connections shall be in accordance with MSS SP-45. 4.10 Lubricat
47、ion-Seal Lubricated plug valves shall be furnished with a lubricating-sealing system to provide a means for delivering plug valve lubricant-sealant to the body-plug interface. 4.10.1 Grooves Grooves shall be provided in the plug and/or body of the body-plug interface surfaces to effectively seal the
48、 ports and facilitate operation. These grooves shall be so arranged that lubricant pressure may be transmitted to all parts of the system when the valve is fully open or closed. 4.10.2 Lubricant-Sealant Fittings A lubricant-sealant fitting shall be provided in each valve for injection of the lubrica
49、nt-sealant by means of a lubricant gun. This fitting may include a compression screw so that stick lubricant-sealant can be inserted manually. The lubricant-sealant fitting, including the screw, shall be made of steel. 4.10.3 Lubricant Seal Check Valves Check valves are required on all lubricated plug valves to prevent escape of lubricant-sealant. Material for check valves, including valve element and housing, shall be steel. MSS STANDARD PRACTICE SP-784 5. PRESSURE-TEMPERATURE RATINGS 5.1 Pressure-temperature ratings are shown in T
