1、 MSS SP-79-2011 Socket Welding Reducer Inserts 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.org MSS www.mss-h
2、q.org MSS STANDARD PRACTICE SP-79i This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 105 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide an effective, clear
3、, 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 itself preclud
4、e 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 it undertak
5、e, 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 otherwise specifically note
6、d in this MSS Standard Practice, other standards documents referred to herein are identified by the date of issue that was applicable to this Standard Practice at the date of issue of this Standard Practice (see Annex A). This Standard Practice shall remain silent on the applicability of those other
7、 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 noted as supplemental in the text.” By publication of this Standard Practice, no position is taken with respect to the validity o
8、f any potential claim(s) or of any 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 Standa
9、rd Practice, all text, notes, annexes, 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 “suppl
10、emental”. Note that supplemental information does not include mandatory requirements. The SI (metric) units and U.S. customary units in this Standard Practice are regarded separately as the standard; each should be used independently of the other. Combining or converting values between the two syste
11、ms may result in non-conformance with this Standard Practice. This document has been substantively revised from the previous 2009 edition. It is suggested that if the user is interested in knowing what changes have been made, direct page by page comparison should be made of this document and that of
12、 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-79-2011 with permission
13、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 Fitting
14、s Industry Inc. All rights reserved. Originally Published: March 1974 Current Edition Approved: April 2011 Current Edition Published: October 2011 MSS is a trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright , 2011 by Manufacturers Standardization So
15、ciety of the Valve and Fittings Industry, Inc. Printed in U.S.A. MSS STANDARD PRACTICE SP-79ii FOREWORD This document establishes a Standard Practice for Socket Welding Reducer Inserts produced for a number of years by various manufacturers to varying dimensions although basically similar in princip
16、le. Users should note reducers furnished from existing stocks may have slightly different dimensions than shown in Table 3. Table 3M has been added to this 2011 edition for (SI) metric dimensioned fittings. Other (SI) metric dimensions and the 2010 Errata Sheet have also been incorporated into this
17、2011 edition. MSS STANDARD PRACTICE SP-79iii TABLE OF CONTENTS SECTION PAGE PURPOSE 1 1 SCOPE . 1 2 GENERAL . 1 3 RATINGS . 2 4 SIZE . 2 5 MARKING . 2 6 MATERIAL . 3 7 DESIGN AND CAPABILITY . 3 8 DIMENSIONS AND TOLERANCES . 3 9 TESTING . 3 10 FINISH . 3 11 CORROSION PROTECTION . 3 12 CAUTIONARY NOTE
18、 REGARDING INSTALLATION OF SOCKET WELDED JOINTS . 4 TABLE 1 Fitting Sizes/Pipe Correlation 4 2 Nominal Wall Thickness of Schedule 160 Pipe, NPS 1/4(DN 8) and NPS 3/8(DN 10) . 4 3 Steel Socket Welding Reducer Insert Dimensions and Tolerances 5 3M Steel Socket Welding Reducer Insert Dimensions and Tol
19、erances (SI) Metric 7 FIGURE 1 Gap Recommendations . 9 2 Welding Gap and Minimum Socket Wall Thickness . 9 ANNEX A Referenced Standards and Applicable Dates 10 MSS STANDARD PRACTICE SP-791 PURPOSE To provide a Standard Practice establishing requirements for insert type fittings, which effectively, a
20、fter welded installation, creates a socket welded reduced end fitting, such as a Tee, 90-degree Ell, Cross, 45-degree Ell, Coupling, etc. 1. SCOPE 1.1 General This Standard Practice covers ratings, dimensions, tolerances, finish, marking and material requirements for socket welding reducer inserts f
21、or use with ASME B16.11, Class 3000 and 6000 socket welding fittings. U.S. customary unit dimensions for these reducer inserts are shown in Table 3 and (SI) metric dimensions are shown in Table 3M. 1.1.1 Fitting Sizes/Pipe Correlation Fittings covered by this Standard Practice are shown in Table 1,
22、by class, size range and correlation to the schedule number or wall designation of pipe for calculation of ratings. 1.1.2 Partial Compliance Fittings Fittings with special dimensions and fittings made from non-standard materials may be designed and manufactured by agreement between the manufacturer
23、and the purchaser, provided they are marked in accordance with the requirements for partial compliance fittings of Section 5.1.1(e). 1.1.3 Welding Except for the CAUTIONARY NOTE (see Section 12) and the GAP RECOMMENDATIONS (see Figures 1 and 2), installation welding requirements are not within the s
24、cope of this Standard Practice. Installation welding shall be done in accordance with the applicable piping system into which the fittings are to be installed. 2. GENERAL 2.1 Referenced Standards Standards and specifications referenced in this Standard Practice are shown in Annex A, which is a norma
25、tive part of this Standard Practice. It is not considered practical to identify the specific edition of each standard and specification in the individual references. Instead, the specific edition reference is identified in Annex A. A fitting made in conformance and conforming to this Standard Practi
26、ce in all other respects will be considered to be in conformance with this Standard Practice, even though the edition reference may have changed in a subsequent addendum to or revision of the standard. 2.2 Codes of Regulations A fitting used under the jurisdiction of the ASME Boiler and Pressure Ves
27、sel Code, the ASME B31 Codes for Pressure Piping, or a governmental regulation is subject to any limitation of that code or regulation. This includes any maximum temperature limitation, or rule governing the use of material at low temperature, or provisions for operation at a pressure exceeding the
28、pressure ratings in this Standard Practice. 2.3 Service Conditions Criteria for selection of fitting type and materials suitable for particular fluid service are not within the scope of this Standard Practice. 2.4 Standard Units The values stated in either U.S. customary units or (SI) metric units a
29、re to be regarded separately as standard. Within the text, the metric units are shown in parentheses. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in non-conformance with t
30、his Standard Practice. SOCKET WELDING AND REDUCER INSERTS MSS STANDARD PRACTICE SP-792 NPS 1/4 3/8 1/2 3/4 1 1 1 2 2 3 4 DN 8 10 15 20 25 32 40 50 65 80 100 3. RATINGS 3.1 General These fittings shall be designated as Class 3000 and Class 6000. 3.1.1 Rating Basis The schedule of pipe corresponding t
31、o each Class of fitting for rating purposes is shown in Table 1. Design temperature and other service conditions shall be limited as provided by the applicable piping code of regulation for the material of construction of the fitting. Within these limits the maximum allowable pressure of a fitting s
32、hall be that computed for straight seamless pipe of equivalent material (as shown by comparison of composition and mechanical properties in the respective material specifications). The wall thickness used in such computation shall be that tabulated in ASME B36.10M for the size and applicable manufac
33、turing tolerances and other allowances. Any corrosion allowance and any variation in allowable stress due to temperature or other design shall be applied to the pipe and the fitting alike. 3.1.2 Non-Standard Pipe Wall Thickness Since ASME B36.10M does not include Schedule 160 thickness for NPS 1/4(D
34、N 8), and NPS 3/8(DN 10); the values in Table 2 may be used as the nominal wall thickness of the pipe for rating purposes. 3.2 Pressure Test Capability Pressure testing is not required by this Standard Practice; however, the fitting shall be capable of withstanding hydrostatic test pressure required
35、 by the applicable piping code for the seamless pipe material equivalent to the fitting and of the schedule or wall thickness correlated with fitting class. 4. SIZE 4.1 General The reducer insert size is identified by its nominal pipe size (NPS). NPS is related to the reference nominal diameter, DN,
36、 used in international standards. The relationship is as shown in the table below: The largest pipe size of the reducer insert shall be listed first, followed by the smaller pipe size. 5. MARKING 5.1 General Each fitting shall be permanently marked with the required identification by stamping, elect
37、ro-etching, or vibro-tool marking. Fittings shall be marked on the O.D., at the reduced opening end of the fitting, in a location such that the marking will not be obliterated as a result of welding installation. 5.1.1 Specific Marking The marking shall include (but not limited to) the following: a)
38、 Manufacturers Name or Trademark b) Material Identification Fittings shall be marked in accordance with requirements of either the applicable ASTM Fitting Specification(s) A234, A403, and A420, or the appropriate ASTM Forging Specification(s) A105, A182, and A350. The material log or heat number tra
39、ceable to the material shall be part of the material identification. c) Class Designation 3000 or 6000 as applicable Alternatively, the designation 3M or 6M, as applicable, may be used where M indicates 1000. d) Size The nominal pipe size(s), (NPS or DN), related to the end connections. e) Product C
40、onformance Full compliance fittings shall be marked with the symbol “SP79” to denote conformance with this Standard Practice. Partial compliance fittings covered in Section 1.1.2 shall not be marked “SP79” and if marked with an ASTM designation, the marking shall include the number of the applicable
41、 “Supplementary Requirement” (S58) for special or non-standard fittings, as per ASTM 960-S58. MSS STANDARD PRACTICE SP-793 5.2 Omission of Markings Where size and type of fitting do not permit all of the above markings, they may be omitted in the reverse order given above. 6. MATERIAL 6.1 The materi
42、al for fittings shall consist of forgings, bar, seamless pipe, or tubular products, which conform to requirements for the melting process, and chemical composition requirements of the forging product form as listed in ASME B16.34,Table 1; including applicable notes from Table 2 or Table VII-2 of the
43、 aforementioned standard. 6.2 Non-Standard Materials When fittings of other materials reference this Standard Practice for Non-Standard coverage, they shall be marked as agreed between the manufacturer and purchaser and shall not include the identification specified in Section 5.1.1(b) and (c) of th
44、is Standard Practice. 7. DESIGN AND CAPABILITY These reducers are to be used as a reducing adapter between a straight size socket weld fitting and a smaller size pipe. By the nature of the part configuration, the minimum body wall thickness at the shank end will always be greater than the nominal wa
45、ll thickness of the pipe, as established by ASME B36.10M with which they are used. 8. DIMENSIONS AND TOLERANCES 8.1 General The dimensions and tolerances for reducer inserts capable of meeting these requirements are shown in Table 3 (U.S. customary units) or Table 3M (SI metric units). 8.1.1 Reducer
46、 ends shall be at right angles to the axis and provide adequate surface against which to weld (see Figure 2). 8.1.2 Socket Depth The socket depth shall be no less than the minimum values shown in Table 3 or Table 3M. 8.1.3 Socket Bore The inside surface of the socket bore shall present a workmanlike
47、 finish that is free of burrs. 8.1.4 Minimum Wall In order to provide the required shoulder for the fillet weld, the socket wall thickness at the welding end shall be at least 1.25 times the nominal thickness of the corresponding pipe shown in Table 3 or Table 3M, under column heading “Wall Min C”.
48、U.S. customary inch tolerances are shown at the bottom of Table 3 and (SI) metric tolerances at the bottom of Table 3M. 8.2 Additional Tolerances Tolerances in addition to those listed in Table 3 or Table 3M are as follows: (a) Concentricity of Bores The socket and fitting bores shall be concentric
49、within a tolerance of 0.03 inches (0.8 mm). (b) Concentricity of Axes The maximum allowable variation in the alignment of the fitting bore and socket bore axes shall be 0.06 inches in 1 foot (1.5 mm in 300 mm). 9. TESTING 9.1 Proof Testing Proof testing for fittings made from standard materials are not required by this Standard Practice. 10. FINISH 10.1 Surfaces must be free of sharp burrs and have a workmanship like finish. 11. CORROSION PROTECTION 11.1 Fittings shall be effectively protected against corrosion. Excess oils shall be considered unacceptable as corrosion p
