Low Cycle Fatigue Behavior of Elbows with Local Wall Thinning

Abstract

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.

Study On Carbon Fibre Reinforced Polymer Optimization as Wrapping Structure at 90 Degree Elbows in Piping Using Simulation

“…Three defects' locations were determined on elbows and defects were set 100% wall loss. For this defect location had been referred to an article from Muhammad Faiz Harun, et al, research about low cycle fatigue behavior of elbows with local wall thinning [13]. In an experiment conducted by Karamanos et al [14], bending moments are applied at the end section of straight pipes.…”

“…The CFRP wrapper is considered as orthotropic material and every material properties value needs to determine in material list. Besides, CFRP wrapper Elastic modulus and Thermal Expansion Coefficient were based on the general properties of Carbon Steel [12,13]. Table 4 shows the CFRP wrapping structure parameters.…”

The Effect of Tropical Environment on Fatigue Failure in Royal Malaysian Airforce (RMAF) Aircraft Structure and Operational Readiness

“…The authors would like to express their greatest appreciation and utmost gratitude to the Ministry of Higher Education for awarding the Fundamental Research Grant Scheme, Razak Faculty of Technology and Informatics, Universiti Teknologi Malaysia (UTM) [ 28 ], RMAF Centre of Aerospace Engineering Services Establishment, Subang Airbase, Shah Alam Selangor, Science & Technology Research Institute for Defence (STRIDE), Kajang, Selangor, and CAIDMARK Sdn Bhd, Damansara Utama, Petaling Jaya, Selangor for all the support towards making this study a success.…”

High-Strength Low-Alloy Steels

“…Guo et al [16] evaluated the variability in the mechanical properties of pipeline steel associated with the centreline segregation in continuously cast slab to meet the requirements of strain-based design.Ślęzak [17] studied the fatigue crack initiation and fatigue crack growth in welded joints made of S960QL high-strength low-alloy steel subjected to straincontrolled conditions. Harun et al [18] analysed the effect of the localized wall thinning on low-cycle fatigue resistance of elbows, with artificially introduced defects, made of C70600 steel from full-scale tests.…”