0
TECHNICAL PAPERS

Tensile Properties of Cold Bends for Line Pipes

[+] Author and Article Information
Naoki Fukuda

 Tokyo Gas Co., Ltd., 1-5-20, Kaigan, Minato-ku, Tokyo, 105-8527, Japanfnaoki@tokyo-gas.co.jp

Hiroshi Yatabe

Pipeline Technology Center, Tokyo Gas Co., Ltd., 1-7-7, Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japanyatabe-h@tokyo-gas.co.jp

Tomoki Masuda

 Tokyo Gas Co., Ltd., 1-5-20, Kaigan, Minato-ku, Tokyo, 105-8527, Japant-masuda@tokyo-gas.co.jp

Masao Toyoda

Department of Manufacturing Science, Osaka University, 2-1, Yamada-oka, Suita, Osaka, 565-0871, Japantoyoda@mapse.eng.osaka-u.ac.jp

J. Offshore Mech. Arct. Eng 129(3), 229-235 (Jan 19, 2007) (7 pages) doi:10.1115/1.2746395 History: Received April 01, 2006; Revised January 19, 2007

To comprehensively investigate the tensile properties of cold bends, full-scale cold bending experiments, tensile tests using prestrained small-scale specimens, and finite element (FE) analyses of the cold bending processes were conducted on API 5L X60 and X80 grade line pipes. The tensile tests revealed that the tensile properties of the cold bends were comparable to the uniaxially prestrained specimens machined from the straight part of the pipes. A FE model simulating the cold bending process was verified with the full-scale experimental results in terms of the distributions of residual strains. These results supported a procedure for estimating the tensile properties of the cold bends with a combination of the FE model and the tensile tests using the prestrained specimens; the residual strains obtained from the FE model are transformed into the tensile properties based on the relationship between the residual strains and the tensile properties. This study clarified that the tensile properties come close to being uniformly distributed by reducing the distance between the bending locations; the distance between the bending locations has a significant influence on the overlap of adjacent deformed areas, which governs the distribution of the tensile properties of the cold bends.

Copyright © 2007 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Tensile specimen (in millimeters)

Grahic Jump Location
Figure 2

Stress-strain relationship of pipes (longitudinal direction)

Grahic Jump Location
Figure 3

Schematic of the bending machine

Grahic Jump Location
Figure 4

Bending locations of the pipes

Grahic Jump Location
Figure 5

Stress-strain relationship in prestraining and tensile test (pipe B, prestrain=−1.4%)

Grahic Jump Location
Figure 6

Finite element model (pipe B)

Grahic Jump Location
Figure 8

Relationship between residual strain and yield stress (pipe B)

Grahic Jump Location
Figure 9

Relationship between residual strain and Y∕T (pipe A)

Grahic Jump Location
Figure 10

Relationship between residual strain and Y∕T (pipe B)

Grahic Jump Location
Figure 11

Circumferential distribution of residual strain at bending location (pipe A)

Grahic Jump Location
Figure 12

Circumferential distribution of residual strain at bending location (pipe B)

Grahic Jump Location
Figure 13

Longitudinal distribution of residual strain at α=0deg (pipe A)

Grahic Jump Location
Figure 15

Relationship between maximum compressive residual strain εmax and bending angle θ (pipe A)

Grahic Jump Location
Figure 17

Relationship between deformation length λ and bending angle θ (pipe A)

Grahic Jump Location
Figure 18

Relationship between deformation length λ and bending angle θ (pipe B)

Grahic Jump Location
Figure 19

Longitudinal residual strain at α=0deg (pipe A)

Grahic Jump Location
Figure 20

Longitudinal residual strain at α=0deg (pipe B)

Grahic Jump Location
Figure 21

Longitudinal cumulative residual strain and transformed yield stress at 600mm interval between bending locations (pipe A)

Grahic Jump Location
Figure 22

Longitudinal cumulative residual strain and transformed yield stress at 400mm interval between bending locations (pipe A)

Grahic Jump Location
Figure 14

Longitudinal distribution of residual strain at α=0deg (pipe B)

Grahic Jump Location
Figure 7

Relationship between residual strain and yield stress (pipe A)

Grahic Jump Location
Figure 16

Relationship between maximum compressive residual strain εmax and bending angle θ (pipe B)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In