Determination of the Eextreme Stress in the High-Pressure Drum Power Boilers

10.12737/7782 ◽  
2014 ◽  
Vol 2 (2) ◽  
pp. 83-90
Author(s):  
Михаил Сербиновский ◽  
Mikhail Serbinovskiy ◽  
Максим Курепин ◽  
Maksim Kurepin
Keyword(s):  
High Pressure ◽  
Low Cycle Fatigue ◽  
Steam Boiler ◽  
Extreme Stress ◽  
Stress Changes ◽  
Local Stresses ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Welded Pipe

The simulation results of the stress-strain state using the software ANSYS area pipe connection to the steam boiler high pressure drum for pipe connections of various diameters and wall thickness. The areas of extreme local stresses and values of strains caused by the pressure inside the drum and the pipe connection and the temperature gradient in their walls have been determined, stress concentration factors have been calculated. A comparison of the calculated stresses with the stresses obtained by the strain measurement of a physical model of the drum with welded pipe connections has been made. Functions of the extreme stress changes depending on the position of the diametrical section of the pipe connection has been determined. Using the obtained values of stress and concentration coefficients allow to specify the strength calculation of the high-pressure drum and their reliance on low-cycle fatigue

Analysis of Stress Concentrations in Thick Cylinders With Sideholes and Crossholes

1972 ◽  
Vol 94 (3) ◽  
pp. 815-824 ◽  
Author(s):  
J. C. Gerdeen
Keyword(s):  
Stress Concentration ◽  
Stress Concentrations ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Experimental Values ◽  
Pressure Stress ◽  
Shrink Fit ◽  
Outside Diameter ◽  
Theoretical Results

An approximate theoretical analysis is presented for the determination of stress concentration factors in thick walled cylinders with sideholes and crossholes. The cylinders are subjected to both internal pressure and external shrink-fit pressure. Stress concentration factors are plotted as functions of the geometrical ratios of outside diameter-to-bore diameter, and bore diameter-to-sidehole diameter. Theoretical results are compared to experimental values available in the literature and results of experiments described in a separate paper.

A New Approach to Reducing the Stress Concentration Factors of Cross-Bores in Blocks Under High Pressure

2003 ◽  
Author(s):  
Mira K. Sahney
Keyword(s):  
High Pressure ◽  
Stress Concentration ◽  
Test Results ◽  
Element Analysis ◽  
New Approach ◽  
Standard Design ◽  
The Finite Element Analysis ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Fatigue Life Test

The fundamental design of high pressure joints such as crosses and tees has remained the same for many years. However, the introduction of commercially available high pressure equipment operating at 600 MPa and higher has demanded improved designs for these classic connections. This study presents a new design concept for reducing the stress concentration at intersecting crossbores. Both the finite element analysis and the fatigue test results from the standard high pressure design and the new design are compared. The new approach realizes a 17–25% reduction in the stress concentration factors and a 40% improvement in fatigue life test results when compared to the standard design.

Stress-Concentration Factors in Shafts With Transverse Holes as Found by the Electroplating Method

1955 ◽  
Vol 22 (2) ◽  
pp. 193-196
Author(s):  
H. Ōkubo ◽  
S. Satō
Keyword(s):  
Stress Concentration ◽  
Outer Surface ◽  
Maximum Stress ◽  
Accurate Determination ◽  
Slicing Method ◽  
Concentration Factors ◽  
Mathematical Difficulties ◽  
Stress Concentration Factors ◽  
Maximum Stresses

Abstract In this paper the torsion of shafts with transverse holes has been investigated experimentally. Usual methods for stress measurements, such as the method of brittle coatings and the use of sensitive extensometers, are not applied effectively to the present problem because the maximum stress occurs in the bore and does not occur on the outer surface of the shaft. The stress may be measured by the stress-freezing and slicing method but we cannot expect too much from this method for the accurate determination of the stress when the diameter of the hole is comparatively small. In treating the problem theoretically, considerable mathematical difficulties are encountered on account of its axially nonsymmetrical nature. The electroplating method recently developed by one of the authors (1), however, has been proved to be useful in this case, so the maximum stresses in shafts are measured by this method and the stress-concentration factors are found for various diameters of the hole.

A Multidimensional FEA Approach for Determination of Hot Spot Stresses in Offshore Jacket Structures

2021 ◽  
Author(s):  
Kris Hectors ◽  
Hasan Saeed ◽  
Wim De Waele
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Hot Spot ◽  
Wave Spectrum ◽  
Wave Direction ◽  
Tubular Joints ◽  
Jacket Structures ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract A new fatigue lifetime assessment approach for offshore jacket structures is presented. It combines a previously developed numerical framework for automated determination of stress concentration factors in tubular joints and a multidimensional finite element modelling approach. The approach is explained based on a case study of an OC4 type offshore jacket. To determine the fatigue life, a directional wave spectrum is combined with the JONSWAP spectrum. The fatigue life of the jacket is assessed for two different sea states. Based on the fatigue analysis the most fatigue critical wave direction is identified. The hot spot stresses in one of the most critical joints are determined and compared to stresses obtained with the Efthymiou equations. The shortcomings of these equations are highlighted and it is shown how the numerical framework can be used to improve the current fatigue design philosophy for offshore jackets which relies on the Efthymiou equations for stress concentration factors in the welded tubular joints.

Methods for determination of local stresses in welded pipe joints (Review)

2019 ◽  
Vol 2019 (3) ◽  
pp. 55-63
Author(s):  
P.N. Tkach ◽  
◽  
A.V. Moltasov ◽  
I.G. Tkach ◽  
S.N. Prokopchuk ◽  
...  
Keyword(s):  
Local Stresses ◽  
Pipe Joints ◽  
Welded Pipe

Predicting Catastrophic OD Initiated Fatigue Failure of Thick-Walled Cylinders Using Low Cycle Fatigue Data

1983 ◽  
Vol 22 ◽  
Author(s):  
Joseph A. Kapp
Keyword(s):  
Crack Growth ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Analysis Method ◽  
Life Data ◽  
Fatigue Data ◽  
Concentration Factors ◽  
Crack Initiation Life ◽  
Stress Concentration Factors

ABSTRACTA procedure is presented to predict fatigue failure of thick-walled cylinders containing discontinuities at the OD. Both crack initiation life and crack growth are considered. The elastic-plastic strains at an OD discontinuity are estimated using an elastic analysis and stress concentration factors. The strain estimates are then used in conjunction with low cycle fatigue data to determine the initiation life. Crack growth life is estimated by integration of a power law relationship. The results obtained by using this analysis method compared to measured fatigue life data for several OD initiated failures in thick-walled cylinders agrees to within about 10 percent.

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