0
Research Papers: Design and Analysis

Damage Evolution and Life Prediction of a P91 Longitudinal Welded Tube Under Internal Pressure Creep

[+] Author and Article Information
Takashi Ogata

 Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196, Japantogata@criepi.denken.or.jp

Takayuki Sakai, Masatsugu Yaguchi

 Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196, Japan

J. Pressure Vessel Technol 132(5), 051204 (Aug 23, 2010) (9 pages) doi:10.1115/1.4001688 History: Received December 05, 2008; Revised April 12, 2010; Published August 23, 2010; Online August 23, 2010

The clarification of creep damage mechanism and the establishment of remaining life prediction methods of longitudinal welded piping of P91 steel are important subjects to maintain a reliable operation of boilers in thermal power plants. Internal pressure creep tests were conducted on P91 steel longitudinal welded tubes to characterize the evolution of creep damage with time and to evaluate a life prediction method. Interrupted creep tests were performed for damage observation in addition to rupture tests. Three dimensional finite element creep analyses of the longitudinal welded tube specimens were conducted to identify the stress and creep strain distributions within the specimen during creep. Failure occurred at a heat affected zone (HAZ) without a significant macroscopic deformation. It was found that the initiation of creep voids had concentrated at the midthickness region in the HAZ rather than in the surface. The creep analysis results indicated that the triaxial tensile stress yielded at the midthickness region in the HAZ due to difference of creep deformation property among the base metal, the HAZ, and the weld metal. It was suggested that the triaxial stress state caused acceleration of the creep damage evolution in the HAZ, resulting in internal failure of the tube specimens. A rupture time prediction method of the welded tube is proposed based on the maximum principal stress and the triaxial stress factor in the HAZ. The void growth behavior in the HAZ was well predicted by the previously proposed void growth simulation method by introducing a void initiation function to the method.

Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Microstructure and hardness distribution of a mod. 9Cr weld joint specimen

Grahic Jump Location
Figure 2

Internal pressure creep rupture test results

Grahic Jump Location
Figure 3

Damage condition of the rupture specimen under the internal pressure creep

Grahic Jump Location
Figure 4

Void number density at the heat affected zone in the section of interrupted and failure specimens

Grahic Jump Location
Figure 5

Comparison of void number density and area fraction rate between surface and midthickness

Grahic Jump Location
Figure 6

Finite element model of longitudinal welded tube specimen

Grahic Jump Location
Figure 7

Circumferential stress distribution in the specimen

Grahic Jump Location
Figure 8

Stress distribution from the outer to the inner surface along the center line at the HAZ

Grahic Jump Location
Figure 9

Stress change with time at the maximum stress portion

Grahic Jump Location
Figure 10

Distribution of triaxiality factor in the HAZ from the outer to the inner surface

Grahic Jump Location
Figure 11

Dependency of limited strain on maximum stress in the HAZ

Grahic Jump Location
Figure 12

Flow of the void growth simulation

Grahic Jump Location
Figure 13

Void growth simulation results at the outer surface and the maximum stress portion

Grahic Jump Location
Figure 14

Comparison of void growth simulation and observation at the outer surface and the maximum stress portion

Grahic Jump Location
Figure 15

Comparison of void number density distribution between prediction by simulation and observation

Grahic Jump Location
Figure 16

FE model of the longitudinal welded elbow

Grahic Jump Location
Figure 17

Circumferential stress and creep strain distribution after 100,000 h

Grahic Jump Location
Figure 18

Stress distribution after 100,000 h

Grahic Jump Location
Figure 19

Void growth simulation results the maximum stress portion in the HAZ of the elbow pipe

Grahic Jump Location
Figure 20

Void number density with time at the outer surface and the maximum stress portion

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