Low Cycle Fatigue Behavior and Seismic Assessment for Pipe Bend Having Local Wall Thinning-Influence of Internal Pressure

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Yoshio Urabe ◽  
Koji Takahashi ◽  
Kyohei Sato ◽  
Kotoji Ando
Keyword(s):  
Internal Pressure ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Safety Margin ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Pipe Bend ◽  
Wall Thinning ◽  
Local Wall Thinning

One of the concerned technical issues in the nuclear piping under operation is pipe wall thinning caused by flow accelerated corrosion. This paper focuses on influence of internal pressure on low cycle fatigue life of pipe bends with local wall thinning and evaluation of safety margin against seismic loading in order to apply the obtained knowledge to the nuclear piping. In-plane bending fatigue tests under several constant internal pressure magnitudes were carried out using carbon steel pipe bends with local wall thinning at the extrados. Also finite element analysis, code-based seismic evaluation and fatigue analysis based on calculated strain range were carried out. Obtained main conclusions are as follows: (1) the tested pipe bends with local wall thinning at the extrados have a strong resistance against fatigue failure based on nuclear seismic piping design in Japan at least up to 12 MPa. That is, the tested pipe bends with severe local wall thinning (eroded ratio = 0.5 and eroded angle = 180 deg) at the extrados have margins against fatigue failure, even though the wall thickness is less than the code-required minimum value based on the nuclear piping seismic design in Japan. (2) Combination of the conventional B2 index and the Ke factor provided in the JSME Design and Construction Code, which is referred by JEAC 4601-2008 overestimates fictitious stress amplitude, when sum of the primary and secondary stress is much greater than 3 Sm.

scholarly journals Low Cycle Fatigue Behavior of Elbows with Local Wall Thinning

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 260
Author(s):  
Muhammad Faiz Harun ◽  
Roslina Mohammad ◽  
Andrei Kotousov
Keyword(s):  
Power Plants ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Safety Margin ◽  
Active Regions ◽  
Fatigue Loading ◽  
Civil Infrastructure ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

There have been a number of studies concerning the integrity of high-strength carbon steel pipe elbows weakened by local pipe wall thinning, the latter can be typically caused by flow accelerated erosion/corrosion. In particular, the focus of several recent studies was on low cycle fatigue behavior of damaged elbows, mainly, in relation to strength and integrity of piping systems of nuclear power plants subjected to extreme loading conditions, such as earthquake or shutdown. The current paper largely adopts the existing methodology, which was previously developed, and extends it to copper-nickel elbows, which are widely utilized in civil infrastructure in seismically active regions. FE (finite element) studies along with a full-scale testing program were conducted and the outcomes are summarized in this article. The overall conclusion is that the tested elbows with various severity of local wall thinning, which were artificially introduced at different locations, demonstrate a strong resistance against low cycle fatigue loading. In addition, elbows with wall thinning defects possess a significant safety margin against seismic loading. These research outcomes will contribute to the development of strength evaluation procedures and will help to develop more effective maintenance procedures for piping equipment utilized in civil infrastructure.

1251 Effects of local wall thinning on low-cycle fatigue behavior of tee pipes

2008 ◽  
Vol 2008.1 (0) ◽  
pp. 177-178
Author(s):  
Kanako OGINO ◽  
Sota WATANABE ◽  
Koji TAKAHASHI ◽  
Kotoji ANDO
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

Low Cycle Fatigue Behavior and Seismic Assessment for Elbow Pipe Having Local Wall Thinning

2010 ◽  
Author(s):  
Yoshio Urabe ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Fatigue Crack ◽  
Pipe Wall ◽  
Low Cycle Fatigue ◽  
Safety Margin ◽  
Seismic Loading ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Erosion Corrosion ◽  
Technical Issues ◽  
Local Wall Thinning

One of the concerned technical issues in the nuclear piping under operation is pipe wall thinning caused by flow accelerated corrosion. Recently it has been reported that the elbow section is more suspicious on pipe wall thinning by erosion-corrosion. Some researchers including authors have been studied static and fatigue strength of elbows with local wall thinning. However, still more experiment and analysis data are needed to clarify the technical issues. Accordingly, further experiments and their evaluations were carried out by the authors. This paper presents the influences of size and location on fatigue life. Also as one of the application of the test results, safety margin of elbows with wall thinning against seismic loading is discussed. Low cycle fatigue tests were conducted using elbow specimens made of STPT410 steel with local wall thinning. The local wall thinning was machined on the inside of elbow specimens in order to simulate erosion/corrosion metal loss. The local wall thinning areas were located at three different areas, called extrados, crown and intrados. Eroded ratio (eroded depth/wall thickness) is 0.5 and 0.8 and eroded angle is 90deg. and 180deg..The elbow specimens were subjected to cyclic in-plane bending under displacement control (±20mm) without and with internal pressure of 3MPa. Obtained main conclusions are shown bellow. (1) Existence of local wall thinning in extrados does not have an important effect on fatigue life. Especially, fatigue crack does not initiate at the extrados where the extreme local wall thinning exists (eroded ratio = 0.8 and eroded angle = 180 deg.). (2) Regardless of existence of internal pressure, fatigue crack initiates at the crown where local wall thinning does not exist. (3) Even if the eroded ratio and the eroded angle reached up to 0.8 and 180 deg., the elbows with local wall thinning have high safety margin against seismic loading, comparing to ASME Boiler and Pressure Vessel Code Sec. III allowable seismic stress criteria.

scholarly journals Low-cycle fatigue behavior of stainless-steel elbows having local wall thinning

2020 ◽  
Vol 7 (3) ◽  
pp. 19-00582-19-00582
Author(s):  
Yasuhiro ASHIBA ◽  
Yuu KOIZUMI ◽  
Koji TAKAHASHI ◽  
Akihiko HIRANO ◽  
Tsuneo TAKAYAMAGI ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

LOW-CYCLE FATIGUE BEHAVIOR OF STAINLESS STEEL ELBOW HAVING LOCAL WALL THINNING

2019 ◽  
Vol 2019.27 (0) ◽  
pp. 1710
Author(s):  
Yasuhiro ASHIBA ◽  
Yuu KOIZUMI ◽  
Koji TAKAHASHI ◽  
Akihiko HIRANO ◽  
Tsuneo TAKAYANAGI ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

OS1424 Effects of inner pressure on low-cycle fatigue behavior of elbow pipes with local wall thinning

2009 ◽  
Vol 2009 (0) ◽  
pp. 219-221
Author(s):  
Kanako OGINO ◽  
Kazuya TAKEUCHI ◽  
Koji TAKAHASHI ◽  
Kotoji ANDO ◽  
Yoshio URABE
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Inner Pressure ◽  
Wall Thinning ◽  
Local Wall Thinning

scholarly journals OS2509 Effects of location of local wall thinning on the low cycle fatigue behavior of elbow pipe

2011 ◽  
Vol 2011 (0) ◽  
pp. _OS2509-1_-_OS2509-3_
Author(s):  
Koji TAKAHASHI ◽  
Kyohei SATO ◽  
Kazuya MATSUO ◽  
Kotoji ANDO ◽  
Yoshio URABE
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

1250 Effects of local wall thinning on low-cycle fatigue behavior of elbows

2008 ◽  
Vol 2008.1 (0) ◽  
pp. 175-176
Author(s):  
Koji TAKAHASHI ◽  
Sota WATANABE ◽  
Kotoji ANDO ◽  
Akitaka HIDAKA ◽  
Masakazu HISATSUNE
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Wall Thinning ◽  
Local Wall Thinning

Effect of Local Wall Thinning on Low-Cycle Fatigue Behaviors of Elbow With Internal Pressure: Estimation of Fatigue Life Based on Revised Universal Slope Method

2013 ◽  
Author(s):  
Koji Takahashi ◽  
Kyohei Sato ◽  
Kazuya Matsuo ◽  
Kotoji Ando ◽  
Yoshio Urabe ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Local Buckling ◽  
Cycle Fatigue ◽  
Slope Method ◽  
Wall Thinning ◽  
Local Wall Thinning

Low-cycle fatigue tests and finite element analysis were conducted using 100A elbow specimens made of STPT410 with local wall thinning in order to investigate the influences of local wall thinning on the low-cycle fatigue behaviors of elbows with internal pressure. Local wall thinning was machined on the inside of the elbow in order to simulate metal loss by flow-accelerated corrosion. The local wall thinning located in three different areas, called extrados, crown and intrados. Eroded ratio (eroded depth/wall thickness) was 0.5 and 0.8. The elbow specimens were subjected to cyclic in-plane bending under displacement control with internal pressure of 0 or 9 MPa. Fatigue failure was classified into two types. The one is the type of fatigue crack initiation and another is the type of crack initiation after local buckling. In the type of fatigue crack initiation, fatigue crack initiated at crown and propagates to the axial direction. In the type of crack initiation after local buckling, at first local buckling occurs and secondary, crack initiates at the same place and propagates to the circumferential direction. The low-cycle fatigue lives of elbows were predicted conservatively by the revised universal slope method.

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