Research on the Fatigue Assessment Method for Steel Pressure Vessels Containing Surface Defects

2014 ◽  
Vol 628 ◽  
pp. 137-141
Author(s):  
Xian Lei Meng
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Life Prediction ◽  
Safety Assessment ◽  
Surface Defects ◽  
Great Influence ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Test Results ◽  
Fatigue Assessment

Defects have great influence on the safe running of pressure vessels, and the safty assessment for in-service pressure vessels containing defects can realize safe and economical operation of presure vessles.Aiming at the fatigue assement of defect in steel pressure vessels,the fatigue assement method is studied and a primary program can be uesd to calculate fatigue crack propagation and life prediction is programed based on GB19624.The comparison between test and calculated results indicates that the method provided is suitable for fatigue assessment of defects.Combining the test results and cricical conditonds, the presient approach can provide a basis for the fatigue safety assessment and the reasonable overhaul cycle of in-service pressure vessels.

Study on the Test of Fatigue Life Prediction for X80 Line Pipe

2014 ◽  
Vol 692 ◽  
pp. 387-390
Author(s):  
Qiu Rong Ma ◽  
Yang Li ◽  
Kun Yang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Life Prediction ◽  
Safety Margin ◽  
Fatigue Life Prediction ◽  
Test Results ◽  
Line Pipe ◽  
Work Condition ◽  
Submerged Arc

This paper researched the test of fatigue crack propagation of grade X80 submerged arc welded pipes. According to the test results, analyzed and calculated the fatigue life of submerged arc welded pipes for X80 with half elliptical crack defects at the simulated work condition of shutdown. On a single simulated work condition, the fatigue life of submerged arc welded pipes for X80 with Ф1219×22.0mm is 62 years, which had enough safety margin for fatigue life.

Pre-Strain Effects on Mixed-Mode Fatigue Crack Propagation Behaviour of the P355NL1 Pressure Vessels Steel

2018 ◽  
Author(s):  
João Ferreira ◽  
José A. F. O. Correia ◽  
Grzegorz Lesiuk ◽  
Sergio Blasón González ◽  
Maria Cristina R. Gonzalez ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Mixed Mode ◽  
Pressure Vessels ◽  
Mode I ◽  
Pure Mode

Pressure vessels and piping are commonly subjected to plastic deformation during manufacturing or installation. This pre-deformation history, usually called pre-strain, may have a significant influence on the resistance against fatigue crack growth of the material. Several studies have been performed to investigate the pre-strain effects on the pure mode I fatigue crack propagation, but less on mixed-mode (I+II) fatigue crack propagation conditions. The present study aims at investigating the effect of tensile plastic pre-strain on fatigue crack growth behavior (da/dN vs. ΔK) of the P355NL1 pressure vessel steel. For that purpose, fatigue crack propagation tests were conducted on specimens with two distinct degrees of pre-strain: 0% and 6%, under mixed mode (I+II) conditions using CTS specimens. Moreover, for comparison purposes, CT specimens were tested under pure mode I conditions for pre-strains of 0% and 3%. Contrary to the majority of previous studies, that applied plastic deformation directly on the machined specimen, in this work the pre-straining operation was carried out prior to the machining of the specimens with the objective to minimize residual stress effects and distortions. Results revealed that, for the P355NL1 steel, the tensile pre-strain increased fatigue crack initiation angle and reduced fatigue crack growth rates in the Paris region for mixed mode conditions. The pre-straining procedure had a clear impact on the Paris law constants, increasing the coefficient and decreasing the exponent. In the low ΔK region, results indicate that pre-strain causes a decrease in ΔKth.

scholarly journals Fatigue Life Prediction of Rolling Bearings Based on Modified SWT Mean Stress Correction

2020 ◽  
Author(s):  
Aodi Yu ◽  
Hong-Zhong Huang ◽  
Yan-Feng Li ◽  
He Li ◽  
Ying Zeng
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Stress Ratio ◽  
Prediction Models ◽  
Great Influence ◽  
Sensitivity Coefficient ◽  
Model Verification ◽  
Mean Stress ◽  
Test Results ◽  
Rolling Bearings

Abstract Mean stress has a great influence on fatigue life, commonly used stress-based life prediction models can only fit the test results of fatigue life under specific stress ratio or mean stress but cannot describe the effect of stress ratio or mean stress on fatigue life. Smith, Watson and Topper (SWT) proposed a simple mean stress correction criterion. However, the SWT model regards the sensitivity coefficient of all materials to mean stress as 0.5, which will lead to inaccurate predictions for materials with a sensitivity coefficient not equal to 0.5. In this paper, considering the sensitivity of different materials to mean stresses, compensation factor is introduced to modify the SWT model, and several sets of experimental data are used for model verification. Then, the proposed model is applied to fatigue life predictions of rolling bearings, and the results of proposed method are compared with test results to verify its accuracy.

Analysis and Experimental Verification of SCC Characteristics of Typical Chinese Steels for Pressure Vessels Under Wet H2S Environment

2006 ◽  
Author(s):  
Xuedong Chen ◽  
Jialing Jiang ◽  
Tiecheng Yang ◽  
Jiushao Hu ◽  
Zhibin Ai ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Critical Concentration ◽  
Dynamic Control ◽  
Control Process ◽  
Critical Stress Intensity Factor ◽  
Pressure Vessels ◽  
Concentration Limit ◽  
Test Results ◽  
Hydrogen Induced Cracking ◽  
Chinese Standard

In this paper, the estimation expression of critical concentration for hydrogen-induced cracking and estimation expression of critical stress intensity factor KISCC for hydrogen-induced delayed brittle fracture of the three Chinese steels for pressure vessels — 16MnR, 15MnVR and 07MnCrMoVR in Chinese standard GB 6654 are derived first according to SCC mechanism and in combination with fracture mechanics techniques, and verified by comparison with test values. The estimation expressions of diffusion-dominated crack plateau growth rate da/dt of these three materials are derived using Gerberich model based on the analysis of dynamic control mechanism of hydrogen-induced crack propagation under wet H2S environment and the estimated values are verified with the test results for WOL specimens. And the effect of concentration limit and concentration of the medium at normal temperature on the dynamic control process of crack propagation is also discussed.

Fatigue Crack Propagation in Clad RR58 Sheet to DTD 5070A: Analysis and Correlation of Test Results

1969 ◽  
Vol 73 (700) ◽  
pp. 335-339 ◽  
Author(s):  
D. P. Rooke ◽  
N. J. F. Gunn ◽  
J. T. Ballett ◽  
F. J. Bradshaw
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Aluminium Alloy ◽  
Fatigue Crack Propagation ◽  
Stress Level ◽  
Stress Conditions ◽  
Specimen Geometry ◽  
Aircraft Industry ◽  
Test Results ◽  
Obvious Advantage

In recent years there has been an increasing need for data on the rates of fatigue crack propagation in alloys of interest to the aircraft industry. In general alloys in which cracks grow slowly, under given stress conditions, have an obvious advantage over those in which cracks grow faster; there is more time to detect a crack before failure. It is possible that, in the future, quantitative crack propagation data may be used to give better estimates of the safe life of a structure. There is, however, a need to rationalise the presentation of such data and to study the effect of such parameters as specimen geometry and stress level. Some experiments to investigate the effect of varying some of these parameters in one clad aluminium alloy, DTD 5070A are described. It is a summary of work contained in two RAE Technical Reports.

A Study on Degree of Conservatism of Two Safety Assessment Methods for Piping and Vessels With Defects

2019 ◽  
Author(s):  
Meng He ◽  
Haitao Li ◽  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Liang Sun ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Failure Probability ◽  
Safety Assessment ◽  
Evaluation Method ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Assessment Methods ◽  
Operating Pressure ◽  
Safety Factors ◽  
Straight Pipe

Abstract Flaws (defects), such as local thinning due to corrosion, inevitably exist in piping and pressure vessels. These defects can be evaluated using the fitness for service (FFS) method provided in the GB/T 19624 standard. Recently, the GB/T 35013 standard (Fitness-for-service assessment of pressure equipments), which provides another FFS assessment method for local thinning on piping and vessels, has been published. The evaluation method for local thinning in the GB/T 35013 standard is generally similar to that in the API 579-1/ASME FFS-1 (2016), but is totally different from that in the GB/T 19624. In this paper, the differences of the local thinning assessment methods in the GB/T 35013 (or API 579-1/ASME FFS-1 (2016)) and the GB/T 19624 are summarized, and the degree of conservatism comparisons between these standards are presented. The maximum allowable operating pressure (Prmax) that takes into account the effect of defects for straight pipe sections and vessels under different defect sizes and safety factors in these two standards have been calculated and compared. Monte Carlo simulations have been carried out to estimate the failure probability (Pf) and reliability of the straight pipe sections and vessels with different safety factors using the GB/T 19624.

Safety Assessment and Remaining Service Life Prediction of Sandwich Marine Air Bottles

2013 ◽  
Vol 456 ◽  
pp. 324-329
Author(s):  
Guan Jun He ◽  
Ai Min Diao
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Service Life ◽  
Life Prediction ◽  
Safety Assessment ◽  
Service Life Prediction ◽  
Theoretical Formula ◽  
Remaining Service Life ◽  
Marine Air

Based on the fatigue failure analysis of marine air bottles, the research on the safety assessment and remaining service life prediction is conducted in this paper. Particularly, the method of sandwich evaluation is obtained via sandwich characterization and the formula to calculate the fatigue crack growth rate is obtained via fatigue crack testing: three typical types of sandwich on marine air bottles are investigated, and the corresponding safety assessment results as well as the critical sandwich size are obtained. It is seen that the theoretical formula is valid, and that the air bottle can be safely used till next cycle as long as the initial sandwich angle depth less than 10°.

Fatigue Crack Propagation Analysis of X60 Pipeline Steel Pipelines with Defects

2011 ◽  
Vol 284-286 ◽  
pp. 1148-1151 ◽  
Author(s):  
Mei Bao Chen ◽  
Yu Rong Jiang
Keyword(s):  
Fatigue Crack ◽  
Quantitative Analysis ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Pipeline Steel ◽  
Experimental Investigations ◽  
Test Results ◽  
Propagation Characteristics ◽  
Propagation Analysis ◽  
Deformation Test

It is impossible to keep pipelines free from defects in the manufacturing, installation and servicing processes. In this paper, pre-tension deformation is used to imitate the defects of the part of material and the electric method is used to measure the distance of the fatigue crack. Experimental investigations were carried out on the fatigue crack propagation characteristics of X60 pipeline steel after different degrees of pre-tension deformation Test results show that the fatigue crack propagation was augmented with the pre-tension deformation increase, especially the crack propagation at the near threshold section. The results of quantitative analysis show, the pre-tension deformation reduced the fatigue crack propagation threshold and increased the crack propagation coefficient; consequently the fatigue performance of the part of mechanical damnification was degenerate.

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