Elasto-Plastic Behavior and Buckling Analysis of Steel Pipelines Exposed to Internal Pressure and Additional Loads

2005 ◽  
Author(s):  
Peter Schaumann ◽  
Christian Keindorf ◽  
Henning Bru¨ggemann
Keyword(s):  
Internal Pressure ◽  
Tensile Force ◽  
Buckling Analysis ◽  
Plastic Behavior ◽  
Plastic Shell ◽  
Steel Pipes ◽  
Four Point Bending ◽  
Shell Buckling ◽  
Critical Strains ◽  
Bearing Behavior

The currently valid worldwide standards allow for taking into consideration plastic deformations in order to achieve a higher degree of utilization. The maximum plastic strains, which can be allowed for steel pipes subjected to internal pressure and additional loads, are particularly interesting. In this paper results of investigations on the elasto-plastic bearing behavior of steel pipelines subjected to internal pressure and bending are presented. Four-point bending tests on eight steel pipes were carried out in order to make the buckling analysis in the elasto-plastic range possible. Finite-element-models were checked by test results for the application on buried pipelines. Taking into account bedding conditions of the pipeline in the soil was made possible. Furthermore, an analytical method based on the differential equation for beams with longitudinal tensile force and variable bending stiffness was developed. It is suitable to determine the elasto-plastic bearing capacity for internal pressure and bending. The collapse due to plastic shell buckling is considered by a limit criterion based on critical strains.

Lateral Loading of Internally Pressurized Steel Pipes

2005 ◽  
Author(s):  
S. A. Karamanos ◽  
K. P. Andreadakis ◽  
A. M. Gresnigt
Keyword(s):  
Internal Pressure ◽  
Test Results ◽  
Steel Pipes ◽  
End Conditions ◽  
Pressure Tubes ◽  
Nonlinear Shell ◽  
Numerical Tools ◽  
Model Equations ◽  
Device Size ◽  
Good Agreement

The paper examines the denting response of tubular members and pipes subjected to lateral (transverse) quasi-static loading, in the presence of internal pressure. Tubes are modeled with nonlinear shell finite elements, and the numerical results are in good agreement with available experimental data. Using the numerical tools, a parametric study is conducted to examine the effects of pressure level, as well as those of denting device size and pipe end conditions. It is mainly concluded that for a given denting displacement, the presence of internal pressure increases significantly the corresponding denting force. A simplified two-dimensional heuristic model is also adopted, which yields closed-form expressions for the denting force. The model equations are in fairly good agreement with the test results and illustrate pipe denting response in an elegant manner.

FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Flange Connections With PTFE Blended Gaskets Subjected to External Bending Moments and Internal Pressure

2017 ◽  
Author(s):  
Koji Sato ◽  
Toshiyuki Sawa ◽  
Riichi Morimoto ◽  
Takashi Kobayashi
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Mechanical Characteristics ◽  
Bending Moment ◽  
Leak Rate ◽  
Bending Moments ◽  
Four Point Bending ◽  
Sealing Performance ◽  
The Difference ◽  
Good Agreement

In designing of pipe flange connections with gaskets, it is important to examine the mechanical characteristics of the connections subjected to external bending moments due to earthquake such as the changes in hub stress, axial bolt forces and the contact gasket stress distribution which governs the sealing performance. One of the authors developed the PTFE blended gaskets and the authors examined the mechanical characteristics of the connections with the PTFE blended gaskets under internal pressure. However, no research was done to examine the mechanical characteristics of the connections with the newly developed PTFE blended gasket subjected to external bending moment due to earthquake. The objectives of the present study are to examine the mechanical characteristics of the connection with PTFE blended gasket subjected to external bending moment and internal pressure and to discuss the difference in the load order to the connections between the internal pressure and the external bending moments. The changes in the hub stress, the axial bolt force and the contact gasket stress distribution of the connection are analyzed using FEM. Using the obtained the gasket stress distribution and the fundamental data between the gasket stress and the leak rate for a smaller test gasket, the leak rate of the connection with the gasket is predicted under external bending moment and internal pressure. In the FEM calculations, the effects of the nominal diameter of pipe flanges on the mechanical characteristics are shown. In the experiments, ASME class 300 4 inch flange connection with 2m pipes at both sides is used and the test gasket is chosen as No.GF300 made by Nippon Valqua Industries, ltd. Four point bending moment is applied to the connection. The FEM results of the hub stress and the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the FEM results of the leak rate are fairly coincided with the measured results.

Sandwich Structures: Analysis of Bonding Techniques between Faces and Core and the Effect of Internal Pressure

2015 ◽  
Vol 825-826 ◽  
pp. 361-368
Author(s):  
Lena Müller ◽  
Benjamin Lehmann ◽  
Götz T. Gresser
Keyword(s):  
Internal Pressure ◽  
Mechanical Characteristics ◽  
Core Material ◽  
Compression Tests ◽  
Bending Properties ◽  
Bonding Quality ◽  
Bending Tests ◽  
Four Point Bending ◽  
Peel Tests ◽  
Bonding Technique

The following work was focused on the analysis of adaptable pressurized sandwich components. The investigations were carried out to study the influence of internal pressure on mechanical characteristics. The bonding quality between core material and outer layers is of particular importance. For analyzing the bonding quality peel tests were conducted. In order to investigate the influence of the internal pressure and also of a bonding technique on bending properties four-point bending tests were carried out. In addition, the pressure characteristics were studied with compression tests during which a compression die was pressed into the component. After the compression tests, the rebound properties of pressurized and standard components were observed and compared.

Evaluation of Alignment Rules Using Stainless Steel Pipes With Non-Aligned Flaws

2009 ◽  
Author(s):  
Kunio Hasegawa ◽  
Katsumasa Miyazaki ◽  
Koichi Saito ◽  
Bostjan Bezensek
Keyword(s):  
Stainless Steel ◽  
Limit Load ◽  
Plastic Collapse ◽  
Paper Briefly ◽  
Limit Loads ◽  
Bending Tests ◽  
Steel Pipes ◽  
Four Point Bending ◽  
Close Proximity ◽  
As Stress

Multiple flaws such as stress corrosion cracks are frequently detected in the same welded lines in pipes. If multiple discrete flaws are in close proximity to one another, alignment rules are used to determine whether the flaws should be treated as non-aligned or as coplanar. Alignment rules are provided in fitness-for-service codes, such as ASME, JSME, API 579, BS 7910, etc. However, the criteria of the alignment rules are different among these codes. This paper briefly introduces these flaw alignment rules, and four-point bending tests performed on stainless steel pipes with two non-aligned flaws. The experimental plastic collapse stresses are determined from the collapse loads and compared with collapse stresses calculated from the limit load criteria. The limit loads are obtained for single non-aligned or aligned coplanar flaws in accordance with the alignment rules. On this basis, the conservatism of the alignment rules in the above codes is assessed.

Studies on Plastic Flow of Anisotropic Metals

1956 ◽  
Vol 23 (3) ◽  
pp. 444-450
Author(s):  
L. W. Hu
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Strain Hardening ◽  
Plane Strain ◽  
Plastic Flow ◽  
Plane Stress ◽  
Biaxial Tension ◽  
Plastic Behavior ◽  
Theory Of Plastic Flow ◽  
Walled Cylinder

Abstract This investigation deals with a study of the plastic behavior of anisotropic metals. By extending Hill’s theory of plastic flow of anisotropic metals, plastic stress-strain relations for anisotropic materials with strain hardening are developed. Applications of these relations are also made to plane-stress and plane-strain problems with anisotropy. The effect of anisotropy on the stress distribution and on the pressure to produce yielding in a thick-walled cylinder under internal pressure is discussed. The influence of anisotropy on the interpretation of conventional biaxial tension-tension and tension-torsion tests is also considered in this study.

Failure Modes of American Petroleum Institute 12F Tanks With a Rectangular Cleanout and Stepped Shell Design

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Eyas Azzuni ◽  
Sukru Guzey
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Failure Modes ◽  
American Petroleum Institute ◽  
Buckling Analysis ◽  
Vacuum Pressure ◽  
Maximum Pressure ◽  
Elastic Buckling ◽  
Shell Design ◽  
Nonlinear Geometry

The design and fabrication of shop-welded and prefabricated relatively small tanks, when compared to field-welded tanks, used in the upstream segment of the oil and gas industry is governed by the American Petroleum Institute specification 12F (API 12F). This study explores the changing designs of API 12F tanks to include a new rectangular cleanout design with reinforcement as shell extension internally of cleanout frame and a stepped shell design. This study also investigated the introduction of two additional tank sizes in addition to existing eleven tank sizes in the current 12th edition of API 12F. The adequacy of the new design changes and proposed tank designs were verified by elastic stress analysis with nonlinear geometry, elastic–plastic stress analysis with nonlinear geometry, and elastic buckling analysis to verify their ability to operate at a design internal pressure of 16 oz/in2 (6.9 kPa) and maximum pressure during emergency venting of 24 oz/in2 (10.3 kPa). A vacuum pressure of 1.5 oz/in2 (0.43 kPa) was also investigated using the elastic buckling analysis. The stress levels and uplift of the tanks are reported in this report to provide insights into the behavior of proposed API 12F tanks exposed to higher internal pressure and vacuum pressure.

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