MSS SP-75 - 2019

 

MSS SP-75-2019

High-Strength, Wrought, Butt-Welding Fittings

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: [email protected] [email protected] 

www.msshq.org

 

 

MSS

STANDARD PRACTICE

SP-75

This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 113, Wrought Welding Fittings, Fittings, and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of knowledgeable and experienced industry volunteers to provide an effective, clear, and non-exclusive standard that will benefit the industry as a whole. This MSS Standard Pract Practice ice describes minimal requirements requirements and is intended as a basis for common practice by the manufacturer, the user, and the industry at large. It is the responsibility of the user of this Standard Practice to establish appropriate safety and health practices and determine the applicability of regulatory requirements requirements prior to use. The existence of an MSS Standard Standard Practice does not in itself itself preclude the manufacture, sale, or use of products not conforming conforming to the Standard Practic Practice. e. 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 undertake, to enforce or certify compliance with this document. Any certification or other statement of compliance with the requirem requirements ents 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 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 Practice (see Annex A). This Standard Practice Practice shall remain silent on the validity of those other standards of prior or subsequent dates of issue even though applicable  provisions may not have changed.”  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. therewith. MSS shall not be held respons responsible ible for identifying any patent rrights. ights. Users are expressly advised that determination of patent rights and the risk of infringement of such rights are entirely their responsibility. For all MSS Standard Practices, the term “shall” means “must” and “shall not” means “must not”. In this Standard Practice, allstandard’s text, notes,message. annexes, tables, figures, and areany construed to be “normative” essential to understand the mes sage. All appendices and references footnotes, or other information informa tion denotedand as “supplemental”, that may be included within this Standard Practice, DO NOT involve mandatory or normative requirements. This Standard Practice has been substantially revised from the previous 2014 edition with input from the API task group on low strength fittings and flanges, CSA materials group, U.S. DOT PHMSA, and several transmission companies that use use this document extensively. Consensus of all concerned was gained through multiple iterations of this document and addressed revisions to the design, proof testing, materials, chemistries, heat treatment, impact testing, and quality control. control. The intent of this revision is to clarify the requirements and help ensure consistent material properties, along with records required to demonstrate compliance with that intent. It is suggested that if the user is interested in knowing what changes have been made, that direct page by page comparison should be made of this document and that of the previous edition.

 Non-toleranced dimensions dimensions in this Standard Practice Practice are nomina nominall unless otherw otherwise ise specified.  Excerpts of this Standard Standard Practice may be quoted w with ith written permi permission. ssion. Credit lines should rread ead ‘Extracted from  MSS SP-75-2019 with permission of the publisher, Manufacturers Standardization Standardization Society of the Valve and Fittings  Industry'. Reproduction Reproduction and/or electronic electronic trans transmissi mission on or dissem disseminatio ination n is prohib prohibited ited under copyright copyright convention convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fittings Industry, Inc.  All rights reserved. reserved. Originally Approved: September 1970 Originally Published: November 1970 Current Edition Approved: August 2019 Current Edition Published: December 2019 MSS is a registered trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright ©, 2019 by Manufacturers Standardization Society of the Valve and Fittings Industry, Inc.

Printed in U.S.A.

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STANDARD PRACTICE

SP-75

TABLE OF CONTENTS SECTION 1 2 3 4

SCOPE ................. .................................... ....................................... ........................................ ....................................... ....................................... ....................................... ............................ ......... 1 PRESSURE RATINGS ................... ...................................... ..................................... ...................................... ....................................... ...................................... ...................... ... 1 DEFINITIONS ..................................... .................. ...................................... ....................................... ....................................... ....................................... ................................... ............... 2 DESIGN PROOF-TEST ...................................... ................... ..................................... ...................................... ....................................... ...................................... ...................... ... 3

5 6 7 8 9 10 11 12 13 14 15 16 17

HYDROSTATIC TESTING ................................... ................. ...................................... ....................................... ....................................... ................................... ............... 5 MATERIALS .................................... ................. ...................................... ...................................... ....................................... ....................................... ...................................... ................... 5 CHEMICAL COMPOSITION ..................................... .................. ..................................... ..................................... ....................................... ................................ ............ 6 TENSILE PROPERTIES ...................................... ................... ..................................... ...................................... ........................................ ...................................... .................. 7 HEAT TREATMENT .................................... ................. ...................................... ...................................... ....................................... ....................................... ......................... ...... 8 TRANSVERSE GUIDED-WELD BEND TESTS (MOVED TO SR-2) .................................... ................. ......................... ...... 8 NOTCH-TOUGHNESS PROPERTIES .................................. .................. .................................... ........................................ ...................................... .................. 8 FITTING DIMENSIONS ..................................... ................... ..................................... ....................................... ........................................ ...................................... .................. 9 TOLERANCES FOR WELDING FITTINGS ..................................... ................... ..................................... ...................................... .......................... ....... 9 MANUFACTURE ....................................... ................... ....................................... ...................................... ....................................... ....................................... .......................... ....... 10 NONDESTRUCTIVE EXAMINATION (NDE) ..................................... .................. ...................................... ....................................... .................... 11 QUALITY CONTROL ....................................... ................... ...................................... ...................................... ........................................ ....................................... ................... 12 MARKING ................. .................................... ....................................... ....................................... ....................................... ....................................... ....................................... .................... 14

TABLE  1 2 3 4 5 6 7 8 9

Maximum Limit of Chemical Elements ...................................... .................. ....................................... ....................................... ................................. ............. 18 Tensile Requirements ..................................... .................. ...................................... ....................................... ....................................... ...................................... ....................... .... 18 Tolerances ....................................... ................... ....................................... ...................................... ....................................... ....................................... ....................................... .................... 19 Dimensions of Elbows ................ ................................... ....................................... ........................................ ....................................... ...................................... ....................... .... 20 Dimensions of Reducing Elbows .................. ...................................... ........................................ ....................................... ...................................... ....................... .... 21 Dimensions of Straight Tees .................................... ................. ....................................... ....................................... ....................................... ................................. ............. 24 Dimensions of Reducing Outlet Tees ...................................... .................. ........................................ ........................................ .................................... ................ 25 Dimensions of Caps ...................................... ................... ..................................... ..................................... ....................................... ....................................... .......................... ....... 28 Dimensions of Reducers .................................... ................. ...................................... ....................................... ........................................ ...................................... .................... 29

FIGURE 1 2 3 ((a, a,b, b,c) c) 4 5 X2-1

Recommended Bevel for Wall Thicknesses (T) at End of Fit Fitting, ting, 0.75 in. or Less ........................ .................. ...... 15 Recommended Bevel for Wall Thicknesses (T) at End of Fitting, Greater than 0.75 in. ............... 15 Acceptable Design for Unequa Unequall Wall Thickness ...................................... .................. ....................................... ....................................... .................... 16 Traverse Face and Root-Bend Test Specimens ..................................... ................ ........................................ ....................................... ....................... ... 16 Guided-Bend Test Jig ................. .................................... ....................................... ........................................ ....................................... ...................................... ....................... .... 17 Longitudinal-B Longitudinal-Bead ead Underbead Cracking Test Specimen ............................................ ......................... ....................................... .................... 37

ANNEX A

Referenced Standards and Applicable Dates ...................................... ................... ....................................... ........................................ ....................... ... 31

APPENDIX  X1

Supplementary Requirements Requirements ..................................... ................... ...................................... ........................................ ....................................... ............................. .......... 34

X2 X3

Longitudinal-B Longitudinal-Bead ead Underbead Cracking Test ...................................... ................... ....................................... ........................................ ....................... ... 37 Recommendat Recommendations ions for Segmenting ................. .................................... ...................................... ....................................... ....................................... ....................... .... 38

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STANDARD PRACTICE

SP-75

HIGH-STRENGTH,, WROUGHT, BUTT-WELDING FITTINGS HIGH-STRENGTH 1.  SCOPE  1.1 This Standard Practice covers factory-made, factory-made, seamless an and d electric welded welded carbon and and low-alloy steel,  butt-welding fittings fittings for use in high pressure gas and oil transmission and distribution distribution systems; including  pipelines, compressor stations, stations, metering and regulating regulating stations, and mains. mains. 1.2 This Standard Practice governs dimensions, tolerances, ratings, testing, materials, chemical and tensile  properties,  proper ties, heat treatment, treatment, notch toughness proper properties, ties, manufact manufacture, ure, inspection, inspection, certification, certification, and marking for high-strength, butt-welding butt-welding fittings NPS NPS 60 and smaller. Dimensional requirements for NPS 14 and smaller are provided by reference to ASME B16.9. 1.3 The term “welding fittings” fittings” applies to but butt-welding t-welding fittings fittings such as elbows, segments segments of elbows, reducing elbows, caps, tees, single or multiple-outlet extruded headers, reducers, and extensions and transition sections(1). Hot indu induction ction bends bends are outside tthe he scope of this Standard Practice. Girth wel weld d requirements are outside the scope of this Standard Practice and are covered by the applicable ASME B31 Code for Pressure Piping and/or customer specifications. 1.4 Fittings may be be made to special dimensions, sizes, shapes, and tolerances, tolerances, or of wrought wrought materials other than those covered by this Standard Practice by agreement between the manufacturer and the  purchaser. When such fittings meet all other stipulations stipulations of this Standard Practice they shall be considered as being in partial compliance therewith, providing they are appropriately marked. 1.4.1 Fittings manufactured manufactured in partial partial compliance, as provided in Section 1.4, shal shalll be identified identified with “Part” following the respective grade designation. 1.5 Fittings specified as “PSL2” will automatically automatically invoke the additional requirements of SR-24 which which are intended to be complementary to PSL2 P SL2 line pipe in the API 5L Specification. 2. PRESSURE RATINGS 2.1 The allowable internal-pressure internal-pressure ratings for pipe fittings designed in accordance with this Standard Practice shall be calculated as for straight seamless pipe (or welded pipe with a joint efficiency factor of 1.0) of equivalent grade, diameter and wall thickness in accordance with the rules established in the applicable sections of ASME B31 Codes. 2.2 All fittings produced produced in accordance with with this Standard Prac Practice tice shall be designed designed to withstand a field hydrostatic test pressure, after installation, at a pressure level equivalent to that required to develop a hoop stress equal to the specified minimum yield strength for pipe of equivalent grade and wall thickness based on Barlow’s Formula, Formula, without failu failure, re, leakage, or impairment of serviceability. Barlow’s formula iiss defined as:

Where:: Where  P   = internal design pressure, psig; S   = specified minimum yield strength of the the mating mating pipe, pipe, ps psi; i; t   = nominal wall thickness of the mating pipe, inches;  D   D  = outside diameter of the the mating mating pipe, pipe, inches. inches.

NOTE:  (1) Lengths of extensions and transitions as agreed upon by purchaser and manufacturer. manufacturer.

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STANDARD PRACTICE

SP-75

2.3 By agreement between the manufacturer and the purchaser, fittings fittings may be tested tested at a higher higher pressure  providing the manufacturer manufacturer is notified of the test pressure pressure to be used. 2.4 The design shall take take into considerati consideration on performance requirements prescribed prescribed above as well as additional factors dictated dictated by the shape of the part part.. These consideration considerationss may require some portion of formed fittings to be thicker than the mating pipe wall. 2.5 The design of fittings shall be established by one of the following methods: methods: 2.5.1 Mathematical analyses contained in nationally nationally recognized pressur pressuree vessel or piping codes (e.g. ASME B31.3 Paragraph 304.2, 304.3; ASME Boiler and Pressure Vessel Code (BPVC), Section VIII, Division 2, Part 4); or 2.5.2 Proof testing in accordance with with Section 4; or 2.5.3 Experimental stress analysis (e.g. ASME BPVC, Section VIII, Division 2, Annex 5F) with validation of results. Hydrostatic testing may be used to validate experimental experimental stress analysis; or 2.5.4 Detailed stress analysis (e.g. ASME BPVC, Section VIII, Divi Division sion 2, Part 5) with validation of results. Strain measurement, photo elastic elastic testing, or hydrostatic hydrostatic testing may be used tto o validate detailed stress analysis. Design report and/or calculations must be made available for purchaser’s review when utilizing the methods in Sections 2.5.1, 2.5.3, or 2.5.4. 3. DEFINITIONS   Hydrostatic test  test :  A fluid test in which pressure vessels, such as pipelines, can be tested for strength and leaks.  Lot : A lot shall consist of all fittings from the same heat of material of the same starting wall thickness, same method of manufacture manufacture and given the same heat treatment treatment in a furnace. furnace. Same heat treatment condition means the same process (e.g. normalize, temper) and the same heat-treating cycles (temperatures, time at temperature, cooling method) are used.  Proof test :  A pressure test to failure or or some predetermined minimum test test pressure to demonstrate demonstrate the reinforcement needed to make the part equal to or greater in strength than the intended mating pipe.  Same basic design configuration configuration::  A specific type of fitting whose configuration can be qualified in Section 4.2.1.  Same method of manufacture manufacture:  The same basic formin forming g and heating methods for forming used iin n making a specific type of fitting (elbows, tees, reducers, or caps).  Size::  Refers to the nominal outside diameter of the mating pipe to which the fitting is attached.  Size Traceability: The manufacturer shall establish and follow documented procedures for maintaining the Traceability: heat and lot identity throughout throughout the entire supply chain. Traceability procedures shal shalll provide means for tracing any fitting to the proper heat and lot, and the chemical and mechanical test results.

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MSS

STANDARD PRACTICE

SP-75

4. DESIGN PROOF-TEST 4.1 Proof tests shall shall be made as set forth in this Standard Practice Practice when the manufacturer chooses proof testing to qualify the fitting design. The pressure design thickness, defined as the wall thickness required in critical areas so that the fitting can pass the design proof test, for each type of fitting shall be determined and recorded. The pressure design thickness thickness for other sizes or wall thicknesses co covered vered in Section 4.4 shall require similar similar percentage or reinforcement proportional by size or thickness. Critical areas are normally the inner radius of elbows, the crotch of tees, the knuckle radius of caps and the large ends of reducers. The proof test shall be based on the computed computed burst pressure of the fitting and its connecting connecting  piping as defined in Section Section 4.3. 4.2 Test Assembly Requirements: Requirements:  4.2.1 Each fitting type type shall be tested tested except the testing testing of certain typ types es of fittings can qualify other fittings as described below: (a)   Fitting Type Tested(a)

Short radius, long radius, reducing long radius, or 3R elbow

(b)

Long radius, reducing long radius, or 3R elbow 3R elbow

Short radius elbows Long radius elbows 3R elbows(b)

Fitting Type Qualified (Provided same pressure design thickness used)

(b)

Straight tee

Straight or reducing tees of any reduction

Reducing tee

Reducing tee with the same or more reduction in outlet size

Caps Concentric reducer

Caps of the same configuration Concentric or eccentric reducers with the same or lesser included transition angle(c)

Eccentric reducer

Eccentric or concentric reducers with the same or lesser included transition angle(c)

NOTES:

(a) Section 4.4 applicabi applicability lity of test results apply apply to all tested and qualifie qualified d fittings. (b) A test of any angle elbow will qual qualify ify any other angle. A segmented elbow that has a test on a geometrically similar 45° or 90°  elbow need not be tested separately. (c) Transition angle is defined as the angle of the conical section and is calculated as follows: Concentric Reducer:         Eccentric Reducer:           Where:    = Angle of transition;

  = Diameter of large end of conical section; section; end nd of conical section; S = Diameter of small e = Length of conical section. section. L 

Fittings that have the same basic design configuration (1) and method of manufacture(2) shall be selected from production for testing and shall be identified as to material, grade and lot, including heat treatment. They shall be inspected for dimensional compliance to this Standard Practice. NOTES:

(1) Examples NOT considered the same basic design configur configurations ations are: Elbows with di different fferent radii, tee teess versus extruded outlet headers, bell shaped (i.e. with tangents) versus conical reducers, and caps of different shapes. (2) Examples NOT considered the same method of manufacture are: Full formed tees versus extruded headers, cold formed versus hot formed or differential heating, and rolled and welded versus die formed reducers. Elbows of the same curvature radius, whether seamless, welded with a joint efficiency factor of 1.00, or  bent from fr om pipe, will have the sa same me pressu pressure re desi design gn thick thickness ness aand nd may be combined com bined o orr mixed to ach achieve ieve the testing factor f  of  of 1.00.

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MSS

STANDARD PRACTICE

SP-75

4.2.2 Straight seamless or welded pipe pipe whose calculated calculated bursting strength is at least as great as the proof test pressure as calculated in Section Section 4.3, shall be welded to each en end d of the fitting to be tested tested.. Pipe sections may have the nominal wall greater than the the thickness indicated by the fitting marki markings. ngs. That greater thickness shall not exceed 1.5 times the nominal pipe wall thickness of the pipe that the fitting marking identifies. Any internal misalignmen misalignmentt greater than 0.06 in. shall be reduced by taper boring at a slope not exceeding 1:3 (18°). Any other unequal wall welding preparation preparation shall be in accordance with Figure 3. The minimum length of pipe pipe sections for closures shall shall be one-half pipe O.D. for greater tthan han  NPS 14 and one pipe O.D. for NPS 14 and smaller. smaller. 4.3 The test fluid shall shall be water water or other liquid. Hydrostatic Hydrostatic pressure pressure shall be applied to the assembly. At least three (3) proof tests for each fitting, joint size, or configuration are recommended. The testing factor f  factor f , based on the number of specimen tests performed in the chart below, shall be used in the computed test equations: Number of Tests

Testing Factor  f  

1 2 3

1.10 1.05 1.00

NOTE:  Tests of geometrically identical fittings of different sizes and wall thicknesses that have overlapping ranges as described in Section 4.4 may be combined to establish the test factor applied to

a set of fittings. Example – testing of a NPS NPS 16, NPS 24 and N NPS PS 30 of the same basic design design configuration and method of manufacture would qualify for a test factor of 1.0 and fittings of that type from NPS 8 to NPS 60.

The test shall be taken to rupture or held at or above the computed minimum proof pressure for a period of at least three (3) minutes. The test is successful if for each of the tests, the fitting fitting withstands without without rupture a proof test pressure at least equal to the computed minimum:

Where:: Where = computed minimum minimum proof test pressure pressure for fitting; = testing factor from table listed in Section 4.3; = actual tensile strength of the test fitting, determined on a specimen representative of the test fitting, which shall meet the tensile strength requirements of the applicable material of Section 6; = nominal pipe wall wall thickness of the pipe that that the fitting marking identifies; identifies; = specified outside diameter of pipe. pipe. 4.4 It is not necessary to conduct conduct an individual test test of fittings with with all combinations of of sizes, wall thicknesses, and materials. materials. A successful proof test on one representative fitting fitting may represent others to the extent described in Sections 4.4.1, 4.4.2, and 4.4.3. 4.4.1 One test fitting fitting may be used to qualify fittings fittings of the same same basic design configuration configuration and method of manufacture with a size range from one-half to twice that for the tested fitting. 4.4.2 One test fitting fitting may be used to qualify fittings fittings of the same same basic design configuration configuration and method of manufacture with ranges from one-half to three times that for the tested fitting.

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MSS

STANDARD PRACTICE

SP-75

4.4.3 The pressure retaining retaining capacity of a fitting of the the same basic design design configuration and method of manufacture made of various grades of steel as listed in Section 6 will be directly proportional to the tensile properties of the materials, materials, provided the yield-to-tensile yield-to-tensile ratio is 0.90 or less. Therefore, it is necessary to test only a single material in a representative fitting to prove the design of the fitting. 4.5 The manufacturer shall shall have a quality quality control (QC) program that verifies verifies the manufactu manufacturing ring process used and ensures that the resulting geometry and pressure design thickness of the fittings or joints manufactured conforms to the geometries tested. The QC program shall control the manufacturing drawings and maintain the QC records showing conformance to these drawings. Tests made in accordance with and at the time of previous editions of this test are not intended to be nullified by the changes made in this edition’s test procedure and requirement provided the design criteria for the type tested can be determined. Whenever a significant change is made in the geometry or method of manufacture, the manufacturer shall either retest the new production or show by analysis that the change would not affect the results of prior tests. Examples of changes in geometry geometry that require retests are a change in thickness thickness or revised toolin tooling g configuration. 4.6 A report of the the testing for each test assembly shall shall be prepared and shall include: include: a) Description of the test, including including the number of tests tests and f factor used to establish establish the target  proof test;  b) Instrumentation and methods methods of calibrations used; c) Material test reports for the the assembly’s assembly’s materials; d) Actual final pressures achieved for each test; e) Length of time from test initiation to the time of burst, or the hold hold time at or above the computed target pressure; f)

Calculations performed;

g) Location of rupture, if any, including a sketch or or photograph(s) photograph(s) of the assembly; h) Actual measured thickness in critical areas. The pressure design thickness required in critical areas shall be reported either on the reports for the individual tests or or on a separate report covering multiple multiple tests. If more than one test is used to establish the test factor f  factor f , all of these tests shall be considered for the determination of the pressure design thickness. The test report shall be made available at the manufacturer’s facility for inspection by the purchaser or regulatory authority. 5. HYDROSTATIC TESTING  5.1 Unless otherwise otherwise agreed upon as per Section Section 2.3, welding fi fittings ttings shall be be capable of withstanding withstanding a hydrostatic test pressure as specified in Section 2.2; however, hydrostatic testing by the manufacturer is not required. 6. MATERIALS 6.1 The steel shall be killed and made to a fine grain grain practice using using recognized melting melting practices. 6.2 The material for fittings fittings shall consist consist of forgings, forgings, plate, seamless or fusion-welded tub tubular ular products with filler metal added. 6.3 Steel shall be suitable for field welding to other fittings, fittings, flanges, and and pipe manufactured to applicable specifications listed in the ASME B31 Codes. 5

 

MSS

STANDARD PRACTICE

SP-75

6.4 If preheating of the material is required required to ensure proper proper weldability under normal field conditions, the manufacturer shall state specific preheat requirements and permanently indicate this on the fitting. 6.5 Since thermomechanical controlled proces processs (TMCP) plate results results in material that loses properties properties when heated over 500 °F, this type of plate plate is not typically used for fitt fitting ing manufacture. If the purchaser wishes to use this material, they must consult with the manufacturer and determine what forming conditions and heat treatments are acceptable for this material’s use. 7. CHEMICAL COMPOSITION 7.1 The determination of the chemical composition of each heat of steel steel used in meeting the requirements requirements of Table 1 shall be determined by a product analysis, unless otherwise noted in the Table, and controlled(1)   by the fitting manufacturer. manufacturer. The heat (ladle) and product analysis analysis shall be reported. The chemical method of analysis shall be done in accordance with a recognized standard (e.g. ASTM A751). 7.2 The choice and use of alloying alloying elements for fittings shall be made by the manufacturer. 7.3 The Carbon Equivalent shall be computed by one of the following equations below (based upon the product analysis):  For: 1)

 For: 2)

Where::  Where = a compliance factor dependent upon carbon content defined defined as follows: follows: Carbon Content, %

Carbon Content, %