Journal of High Pressure Institute of Japan

Study on the Low Cycle Fatigue Strength of Tee Welded Joint in Oil Storage Tank

2nd Report: Low Cycle Fatigue Crack Propagation Behavior

Kotoji ANDO, Yoshiyuki BEPU, Kazushi TOYOTA

1987 Volume 25 Issue 1 Pages 3-10
Published: January 25, 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.3

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Low cycle fatigue tests have been made on the tee welded joints in oil storage tank and CT specimen extracted from the joint. Fatigue tests were mainly done by the method of displacement control, however some specimens were tested by load control or by control to a sloping line.
By the test, the fatigue crack propagation rate of 10^-5mm/cycle up to 1mm/cycle has been obtained. Crack length in welded joint were successfully measured by ultrasonic technique.
The fatigue crack propagation rate during gross plasticity can not be predicted ΔJ critenion alone nor ΔK critenion. However, it can be done by the combination of ΔJ and Jmax criteria, giving an agreement with the extrapolation of linear elastic fatigue crack propagation rate data.

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Erratum

1987 Volume 25 Issue 1 Pages 10
Published: 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.1_10

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Elastoplastic Analysis of a Cylindrical Storage Tank by the Coupling Method of Finite and Boundary Elements

Shoichi YOSHIDA, Masayuki SAITO, Toshiro MIYOSHI

1987 Volume 25 Issue 1 Pages 11-22
Published: January 25, 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.11

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High bending stresses occur in the shell-to-annular joint of a cylindrical storage tank due to the hydrostatic pressure and the plastic region grows around the toe of a fillet weld. Because of the cyclic loading by the contained liquid, the low cycle fatigue evaluation is required.
This paper describes the axisymmetric elastoplastic analysis by the coupling method of finite and boundary elements for this evaluation. In this analysis, the region where is expected to be plastic around the toe of a fillet weld is modeled by solid finite elements, the elastic region of the shell-to-annular joint is modeled by boundary elements, the other main members of a tank are modeled by shell finite elements, and the foundation is dealt with by spring finite elements. At the joint of boundary and shell finite elements, the connection element which is formulated by the penalty method is used. The constitutive equation is based on the combined hardening model in order to consider both strain hardening and Bauschinger effect. The Marcal's method is applied to the determination of the plastic elements, and the elastic-predictor radial-return method is used for the stress correction of the transient elements.

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Weldablity of Invar and Its Large-Diameter Pipe

Tadao OGAWA, Hideo SAKURAI, Toshihiko KOSEKI

1987 Volume 25 Issue 1 Pages 27-37
Published: January 25, 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.27

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Hot cracking susceptibility of Invar was investigated using double-bead Varestraint test. Test results showed that Invar weld metal was more susceptible to reheated cracking than austenitic stainless steel, and sulphur remarkably increased the susceptibility. Metallographical studies revealed that reheated cracking was associated with grain boundary embrittlement and/or liquation of low-melting constituents along the grain boundary, both of which were particulary promoted by sulphur. In order to attain high cracking resistance, sulphur content was required to be reduced to less than 0.002%. Based upon those results, a 60-ton heat was produced. From it, 11.0mm-thick, 660mm-dia., 5000mm-long welded pipes were made. The seam and girth welds of the pipes exhibited good resistance to hot cracking and excellent toughness.

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Modifications of Flaw Evaluation Methods for ASME Boiler and Pressure Vessel Code

Hideo KOBAYASHI

1987 Volume 25 Issue 1 Pages 38-54
Published: January 25, 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.38

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This report summarizes recent modifications and proposals of flaw evaluation methods by the Working Group on Flaw Evaluation and the Task Group for Piping Flaw Evaluation for the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section XI.
Main items of the modifications and proposals are as follows:
(1) Reference fatigue crack growth curves for carbon and low alloy ferritic steels in air environments.
(2) Allowable end-of-evaluation period flaw depth to thickness ratio in base metals (austenitic steel piping).
(3) Allowable end-of-evaluation period flaw depth to thickness ratio for circumferential flaws in flux welds (austenitic steel piping).
(4) A procedure for tearing instability analysis of flaws in piping.
(5) Evaluation of flaws in carbon steel piping.
(6) An equation to compute fatigue crack growth rates for austenitic stainless steels in air environments.
(7) Reference fatigue crack growth curves for austenitic steels in air environments.
(8) Recommended residual stress distributions for austenitic steel pipe welds.
(9) Recommended fatigue and corrosion crack growth rates for austenitic steels.

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JPVRC Symposium “Reliability of Pressure Vessels 2”

Service Induced Damage and Life Prediction of Pressure Vessels

Kunio NARITA

1987 Volume 25 Issue 1 Pages 55-56
Published: January 25, 1987
Released on J-STAGE: August 05, 2010

DOIhttps://doi.org/10.11181/hpi1972.25.55

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