ASME_B31G-2009 Manual for Determining the Remaining Strength of Corroded Pipe...

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ASME_B31G-2009 Manual for Determining the Remaining Strength of Corroded Pipelines



CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Correspondence With the B31 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Evaluation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Tables of Allowable Length of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figures
1.12-1 Corrosion Pit Interaction Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.13-1 Helically Oriented Corrosion Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1-1 Corrosion Parameters Used in Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Tables
3-1 Values of L for Pipe Sizes ≥ NPS 2 and < NPS 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3-1M Values of L for Pipe Sizes ≥ 60 mm and < 168 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . . 9
3-2 Values of L for Pipe Sizes ≥ NPS 6 and < NPS 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3-2M Values of L for Pipe Sizes ≥ 168 mm and < 273 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 11
3-3 Values of L for Pipe Sizes ≥ NPS 10 and < NPS 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3-3M Values of L for Pipe Sizes ≥ 273 mm and < 406 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 13
3-4 Values of L for Pipe Sizes ≥ NPS 16 and < NPS 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3-4M Values of L for Pipe Sizes ≥ 406 mm and < 508 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 15
3-5 Values of L for Pipe Sizes ≥ NPS 20 and < NPS 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3-5M Values of L for Pipe Sizes ≥ 508 mm and < 610 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 17
3-6 Values of L for Pipe Sizes ≥ NPS 24 and < NPS 30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3-6M Values of L for Pipe Sizes ≥ 610 mm and < 762 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 19
3-7 Values of L for Pipe Sizes ≥ NPS 30 and < NPS 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3-7M Values of L for Pipe Sizes ≥ 762 mm and < 914 mm O.D. . . . . . . . . . . . . . . . . . . . . . . . 21
3-8 Values of L for Pipe Sizes ≥ NPS 36 and < NPS 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3-8M Values of L for Pipe Sizes ≥ 914 mm and < 1 066 mm O.D. . . . . . . . . . . . . . . . . . . . . . 23
3-9 Values of L for Pipe Sizes ≥ NPS 42 and < NPS 48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3-9M Values of L for Pipe Sizes ≥ 1 066 mm and < 1 219 mm O.D. . . . . . . . . . . . . . . . . . . . 27
3-10 Values of L for Pipe Sizes ≥ NPS 48 and < NPS 52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3-10M Values of L for Pipe Sizes ≥ 1 219 mm and < 1 320 mm O.D. . . . . . . . . . . . . . . . . . . . 33
3-11 Values of L for Pipe Sizes ≥ NPS 52 and < NPS 56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3-11M Values of L for Pipe Sizes ≥ 1 320 mm and < 1 422 mm O.D. . . . . . . . . . . . . . . . . . . . 39
3-12 Values of L for Pipe Sizes ≥ NPS 56 Through NPS 60 . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3-12M Values of L for Pipe Sizes ≥ 1 422 mm Through 1 524 mm O.D. . . . . . . . . . . . . . . . . . 45
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FOREWORD
It has been recognized within the pipeline industry that some sections of high-pressure pipelines,
particularly those with long service histories, may experience corrosion. It has also been recognized,
through theoretical analysis, scientific research and testing, and industry operating experience,
that some amount of metal loss due to corrosion can be tolerated without impairing the
ability of the pipeline to operate safely. In 1984, ASME published the first edition of the B31G
Manual for Determining the Remaining Strength of Corroded Pipelines. The B31G document
provided pipeline operators with a simplified evaluation method based on the results of analysis
and tests. The application of B31G has enabled pipeline operators to reliably determine safe
operating pressure levels for pipe affected by corrosion, and to determine whether repairs are
necessary in order to continue operating safely.
B31G continued to be reissued by ASME with only minor revisions over time, although other
corrosion evaluation methods had evolved since B31G’s initial publication. A majority of these
other methods are based on the same theoretical model from which the original B31G method
was derived, but may offer some refinement in accuracy. Subsequently, an effort was undertaken
to update the B31G document to recognize certain other corrosion evaluation methods that have
proven sound and that have seen successful use in the pipeline industry. Incorporation of these
other methods into a recognized Code document provides the pipeline operator or other user
with a formalized framework within which to use such methodologies, as well as a wider range
of codified technical options with which to make an evaluation. This 2009 revision of B31G
reflects those objectives. ASME B31G-2009 was approved by the American National Standards
Institute (ANSI) on July 10, 2009.



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