Gray Iron Pipe Flanges and Flanged Fittings

Classes 25, 125, and 250

AN A MERICAN NA TIONAL S T AND ARD

ASME B16.1-2020

(Revision of ASME B16.1-2015)

ASME B16.1-2020

(Revision of ASME B16.1-2015)

Gray Iron Pipe

Flanges and Flanged Fittings

Classes 25, 125, and 250

AN AMERICAN NATIONAL STANDARD

Date of Issuance: November 9, 2020

The next edition of this Standard is scheduled for publication in 2025.

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CONTENTS

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Correspondence With the B16 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

List of Changes in Record Number Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Pressure–Temperature Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4 Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

5 Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

6 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

7 Fitting Dimensions and Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

8 Bolt, Nut, and Gasket Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

9 Hydrostatic Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

10 Certifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Mandatory Appendix

I References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Nonmandatory Appendix

FOREWORD

In 1894, the American Society of Mechanical Engineers (ASME) adopted a standard flange template (“ASME Standard”) for low-pressure service. A “Manufacturers Standard” for pressures up to 250 psi followed in 1901. Around 1910, a group of fittings manufacturers formed an organization that was the forerunner of the present Manufacturers Standardization Society of the Valve and Fittings Industry (MSS) and undertook the design of a line of flanged fittings. A document covering this work was published in 1912.

During the years 1912 through 1914, a Joint Committee of the ASME and the Manufacturers Committee formulated compromise standard dimensions for pipe flanges and flanged fittings for use under saturated steam pressures of 125 psi and 250 psi pressure ranges. The Joint Committee's report was accepted at a conference attended by representatives of ASME, the Manufacturers Committee, the U.S. government, and the National Association of Master Steam and Hot Water Fitters. ASME published this report as the “American Standard for Pipe Flanges, Fittings and Their Bolting” in 1914. In 1918, work was started on standards for 50-lb steam flanges and for 800-lb, 1,200-lb, and 3,000-lb hydraulic flanges, which were subsequently approved by this group.

In 1921, the American Engineering Standards Committee, later known as the American Standards Association (ASA), United States of America Standards Institute (USAS), and more recently, the American National Standards Institute (ANSI), organized Sectional Committee B16 to unify and further develop national standards for pipe flanges and fittings (and later for valves and gaskets). Cosponsors of the B16 Committee were ASME, MSS, and the Heating and Piping Contractors Association [now the Mechanical Contractors Association of America (MCAA)]. Work already in progress on flanges and flanged fittings was assigned to Subcommittee 1 (now Subcommittee A). Following approval by the Subcommittee, the B16 Committee, the cosponsors, and ASA, the standards were published in 1928.

In later work, Subcommittee 1 developed the 25-lb Flange and Flanged Fitting Standard (approved in 1931 as ASA B16b2), which replaced the 50-lb standard that had been originally approved in 1918. Work on the 800-lb Hydraulic Flange Standard was published as ASA B16b1 in 1931. Revision of thicknesses, tolerances, and service pressure ratings of the 125-lb and 250-lb flanges and flanged fittings led to approval and publication of ASA B16a-1939.

An American war standard entitled “Pressure Ratings for Cast Iron Flanges and Flanged Fittings, 125 lb” (ASA B16a1) was published in 1943. A complete review of the 125-lb and 250-lb standards resulted in new editions of each: ASA B16.1-1948 and ASA B16.2-1948. In 1960, editions of B16.1 and B16.2 were issued in which ratings were presented in graphic form and special requirements were added for testing flanges.

A review of all gray iron flange and flanged fittings standards initiated in 1962 resulted in the withdrawal of B16.16, “300 lb Refrigerant Flanges and Flanged Fittings,” and the combining of the remaining standard into a single document, with B16.1 and B16.2 coming together as USAS B16.1-1967. In this edition, the presentation of ratings was restored to tabular form.

The increasing use of higher grades of gray iron necessitated the establishment of a second set of ratings for the smaller sizes. A revised edition published as ANSI B16.1-1975 incorporated these new ratings along with metric (SI) equivalents for dimensions and minor corrections to the 1967 edition text.

In 1982, American National Standards Committee B16 was recognized as an ASME Committee operating under proce- dures accredited by ANSI. Following approval by the ASME B16 Subcommittee A and B16 Committee, ANSI approved ASME/ANSI B16.1-1989 on March 8, 1989. Changes included revised marking requirements, revised bolt length incre- ments (1∕2 in. rather than 1∕4 in.), elimination of metric equivalents, a correction of the Class 800 flange raised-face height to

0.25 in. from the 0.06 in. shown previously, and editorial changes to the text.

In the 1998 edition of ASME B16.1, Reference Standards were updated, a Quality System Program Annex was added, Class 800 was deleted, and several editorial revisions were made. Following approval by ASME B16 Subcommittee B and B16 Main Committee, ANSI approved ASME B16.1-1998 on November 20, 1998.

Work was started in 1999 to revise the standard to include metric units as the primary reference units while main- taining U.S. Customary units in either parenthetical or separate forms. Following approval of the Standard Committee and ASME, approval as an American National Standard was given by ANSI on July 8, 2005, with the new designation ASME B16.1-2005.

In the 2010 edition of ASME B16.1, the Scope was separated into its own paragraph with all following paragraphs renumbered accordingly, references were updated, and several editorial revisions were made. Following approval of the B16 Standards Committee, approval as an American National Standard was given by ANSI on November 17, 2010.

In the 2015 Edition, provisions were made to provide bolt hole tolerances that are appropriate to this Standard. Following the approval by the ASME B16 Standards Committee, approval as an American National Standard was given by ANSI on July 29, 2015.

In ASME B16.1-2020, the U.S. Customary tables in former Mandatory Appendix I have been merged with the SI tables in the main text. The tables and figures have been redesignated, former Mandatory Appendix I has been deleted, and the subsequent Mandatory Appendix has been redesignated. Cross-references have been updated accordingly. Also in this edition, entries for NPS 66, 78, and 90 have been added to Table 7.6.1-2 (formerly Tables 9 and I-9), and the references in Mandatory Appendix I (formerly Mandatory Appendix II) have been updated. Following the approval by the ASME B16 Standards Committee, this revision to the 2015 edition was approved as an American National Standard by ANSI on July 24, 2020, with the new designation ASME B16.1-2020.

ASME B16 COMMITTEE

Standardization of Valves, Flanges, Fittings, Gaskets, and Valve Actuators

(The following is the roster of the Committee at the time of approval of this Standard.)

STANDARDS COMMITTEE OFFICERS

C. E. Davila, Chair

R. Bojarczuk, Vice Chair

C. Ramcharran, Secretary

STANDARDS COMMITTEE PERSONNEL

A. Appleton, Alloy Stainless Products Co., Inc.

J. Barker, Dezurik, Inc.

R. W. Barnes, Anric Enterprises, Inc.

D. C. Bayreuther, Metso Automation

W. B. Bedesem, Consultant

R. Bojarczuk, ExxonMobil Research and Engineering Co.

A. M. Cheta, Qatar Shell GTL

M. A. Clark, Consultant

G. A. Cuccio, Capitol Manufacturing Co.

J. D'Avanzo, Fluoroseal Valves

C. E. Davila, Crane ChemPharma and Energy

K. S. Felder, Valero Energy

D. R. Frikken, Becht Engineering Co.

J. R. Holstrom, Val-Matic Valve and Manufacturing Corp.

D. Hunt, Jr., Fastenal

G. A. Jolly, Samshin, Ltd.

E. J. Lain, Exelon Nuclear

T. A. McMahon, Emerson Process Management

R. C. Merrick, Fluor Enterprises

W. H. Patrick, The Dow Chemical Co.

D. W. Rahoi, CCM 2000

1. Ramcharran, The American Society of Mechanical Engineers

2. Reid, VSP Technologies

R. A. Schmidt, Canadoil

J. Sekerak, CSA Group

J. P. Tucker, Flowserve

F. R. Volgstadt, Volgstadt and Associates, Inc.

J. D. Grant, Alternate, DeZURIK APCO Hilton

P. V. Craig, Contributing Member, Jomar Group

B. G. Fabian, Contributing Member, Pennsylvania Machine Works

A. G. Kireta, Jr., Contributing Member, Copper Development Association, Inc.

SUBCOMMITTEE B — THREADED FITTINGS (EXCEPT STEEL), FLANGES, AND FLANGED FITTINGS (B16)

D. Hunt, Jr., Chair, Fastenal

J. R. Holstrom, Vice Chair, Val-Matic Valve and Manufacturing Corp.

R. Rahaman, Secretary, The American Society of Mechanical Engineers

J. Atkinson, Mueller Industries

W. Bliss, Tyler Pipe Co.

M. A. Clark, Consultant

M. C. Coffey, Ward Manufacturing, LLC

R. Kelsey, Nibco, Inc.

W. H. LeVan, Cast Iron Soil Pipe Institute

G. L. Simmons, Charlotte Pipe and Foundry

G. T. Walden, Ferguson

CORRESPONDENCE WITH THE B16 COMMITTEE

General. ASME Standards are developed and maintained with the intent to represent the consensus of concerned interests. As such, users of this Standard may interact with the Committee by requesting interpretations, proposing revisions or a case, and attending Committee meetings. Correspondence should be addressed to:

Secretary, B16 Standards Committee

The American Society of Mechanical Engineers Two Park Avenue

New York, NY 10016-5990

https://go.asme.org/Inquiry

Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes that appear necessary or desirable, as demonstrated by the experience gained from the application of the Standard. Approved revisions will be published periodically.

The Committee welcomes proposals for revisions to this Standard. Such proposals should be as specific as possible, citing the paragraph number(s), the proposed wording, and a detailed description of the reasons for the proposal, including any pertinent documentation.

Proposing a Case. Cases may be issued to provide alternative rules when justified, to permit early implementation of an approved revision when the need is urgent, or to provide rules not covered by existing provisions. Cases are effective immediately upon ASME approval and shall be posted on the ASME Committee web page.

Requests for Cases shall provide a Statement of Need and Background Information. The request should identify the Standard and the paragraph, figure, or table number(s), and be written as a Question and Reply in the same format as existing Cases. Requests for Cases should also indicate the applicable edition(s) of the Standard to which the proposed Case applies.

Interpretations. Upon request, the B16 Standards Committee will render an interpretation of any requirement of the Standard. Interpretations can only be rendered in response to a written request sent to the Secretary of the B16 Standards Committee.

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Subject: Cite the applicable paragraph number(s) and the topic of the inquiry in one or two words. Edition: Cite the applicable edition of the Standard for which the interpretation is being requested.

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Attending Committee Meetings. The B16 Standards Committee regularly holds meetings and/or telephone confer- ences that are open to the public. Persons wishing to attend any meeting and/or telephone conference should contact the Secretary of the B16 Standards Committee.

ASME B16.1-2020 SUMMARY OF CHANGES

Following approval by the ASME B16 Standards Committee and ASME, and after public review, ASME B16.1-2020 was approved by the American National Standards Institute on July 24, 2020.

In ASME B16.1-2020, the U.S. Customary tables in former Mandatory Appendix I have been merged with the SI tables in the main text. The tables and figures have been redesignated, former Mandatory Appendix I has been deleted, and the subsequent Mandatory Appendix has been redesignated. Cross-references have been updated accordingly. In addition, this edition includes the following changes identified by a margin note, (20). The Record Numbers listed below are explained in more detail in the “List of Changes in Record Number Order” following this Summary of Changes.

LIST OF CHANGES IN RECORD NUMBER ORDER

Record Number Change

17-547 Former Tables 9 and I-9 were merged and redesignated as Table 7.6.1-2 and revised to include NPS 66, 78, and 90 for Class 125 flange and bolt dimensions.

20-863 Former Mandatory Appendix II references were updated.

ASME B16.1-2020

GRAY IRON PIPE FLANGES AND FLANGED FITTINGS CLASSES 25, 125, AND 250

1. SCOPE

   This Standard covers Classes 25, 125, and 250 Gray Iron Pipe Flanges and Flanged Fittings. It includes

   1. pressure–temperature ratings

   2. sizes and method of designating openings of reduc- ing fittings

   3. marking

   4. materials

   5. dimensions and tolerances

   6. bolting and gaskets

   7. pressure testing

      
      

2. GENERAL

1. References

   Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix I, which is part of this Standard. It is not considered practical to identify the specific edition of each referenced standard and specification in the text, when referenced. Instead, the specific editions of the referenced standards and specifi- cations are listed in Mandatory Appendix I.

   
   

2. Quality Systems

   Requirements relating to the product manufacturer's Quality System Programs are described in Nonmandatory Appendix A.

   
   

3. Relevant Units

   This Standard states values in both SI and U.S. Customary units. As an exception, diameter of bolts and flange bolt holes are expressed in inch units only. These systems of units are to be regarded separately as standard. Within the text, the U.S. Customary units are shown in parentheses. The values stated in each system are not exact equivalents; therefore, it is required that each system of units be used independently of the other. Except for diameter of bolts and flange bolt holes, combining values from the two systems constitutes nonconformance with the Standard.

   
   

4. Service Conditions

   Criteria for selection of materials suitable for particular fluid service are not within the scope of this Standard.

5. Convention

   For determining conformance with this Standard, the convention for fixing significant digits where limits (maximum and minimum values) are specified shall be as defined in ASTM E29. This requires that an observed or calculated value be rounded off to the nearest unit in the last right-hand digit used for expressing the limit. Decimal values and tolerances do not imply a particular method of measurement.

   
   

6. Denotation

   1. Pressure Rating Designation. Class, followed by a dimensionless number, is the designation for pressure– temperature ratings as follows:

      Class 25 125 250

      
      

   2. Size. NPS, followed by a dimensionless number, is the designation for nominal flange or flange fitting size. NPS is related to the reference nominal diameter, DN, used in international standards. The relationship is, typically, as follows:

NPS DN

1 25

11∕4 32

11∕2 40

2 50

21∕2 65

3 80

31∕2 …

4 100

GENERAL NOTE: For NPS ≥ 4, the related DN = 25 × (NPS).