Efficient elastic stress analysis method for piping system with wall-thinning and reinforcement

The load bearing behavior of piping systems depends considerably on support distances and stiffness as well as cross section characteristics. Stiffness of supports can often be defined only with difficulty by applying simplified procedures or guidelines based on assumptions. Load cases can be estimated quite well, but the safety assessment of a piping system can only be as reliable as the system model can realistically describe the present support stiffness or imperfections e.g. local wall thinning. As a consequence, the prediction of the system response may be poor. It is likely that calculated frequencies differ from natural frequencies determined experimentally. These frequency shifts lead to unrealistic predictions of stress analysis. Examples for overestimations and underestimations of stress analysis are given regarding the load case earthquake, depending on whether the frequency shift runs into or out of the plateau of the applied floor response spectrum. The influence of local wall thinning on modal characteristics is investigated. Conservative estimations of the influence on the load bearing behavior regarding severe local wall thinning are given. For fatigue checks the linear response of an experimental piping system is calculated and safety margins are demonstrated by comparing calculated with experimental results.

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Elastic Stress Analysis for Case of Corrugated Fiberboard Box Shape Applied Uniform Compression in Upper and Lower Edges. On Standing Plate Approxiluate Analysis Method of Square Tube for Upper and Lower Supported Edges of Zero Displacement.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A ◽

10.1299/kikaia.66.2015 ◽

2000 ◽

Vol 66 (651) ◽

pp. 2015-2021 ◽

Cited By ~ 3

Author(s):

Satoru MATSUSHIMA ◽

Shigeo MATSUSHIMA

Keyword(s):

Stress Analysis ◽

Elastic Stress ◽

Analysis Method ◽

Uniform Compression ◽

Corrugated Fiberboard

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Secondary Stress Weighting Factor and Plastic Reduction Factor of Surface Cracked Pipes Under Bending

Journal of Pressure Vessel Technology ◽

10.1115/1.4050987 ◽

2021 ◽

Author(s):

Sushma Pothana ◽

Gery Wilkowski ◽

Sureshkumar Kalyanam ◽

Yunior Hioe ◽

Gary Hattery ◽

...

Keyword(s):

Stress Analysis ◽

Elastic Stress ◽

Weighting Factor ◽

Reduction Factor ◽

Piping System ◽

Crack Plane ◽

Secondary Stress ◽

Pipe Failure ◽

Elastic Plastic ◽

Two Parameters

Abstract In piping design analysis, the secondary stresses (displacement controlled) may have different design limits than primary stresses (load-controlled stresses). The current design limits for secondary stresses are based on elastic stress analysis. But realistically a flaw in the piping system can cause non-linear behavior due to the plasticity at the crack plane as well as in the adjacent uncracked-piping material. Hence, the actual stresses in a cracked piping system which are elastic-plastic are different than the design stresses which are elastically calculated. To assess margins in the secondary stresses calculated using elastic stress analysis, two parameters are defined in this paper. The first one is the Secondary Stress Weighting Factor (SSWF) on total stress which is defined as the ratio of actual elastic-plastic stresses in a system to the elastic design stress. An alternative approach to applying margins on secondary stresses is to a use a reduction factor only on stresses above the yield stress. This reduced factor is called Plastic Reduction Factor (PRF). In this paper, a methodology developed to determine these factors for circumferential surface-cracked TP304 stainless steel pipes subjected to bending loads at room temperature is described. Four-point-bend tests are conducted on pipes with varying circumferential surface-crack lengths and depths. The moment and rotations needed for the pipe failure for different crack sizes are determined and compared to elastically calculated moments and rotations to establish margins.

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Discussion on the Implementation of the Primary Structure Method in Design by Analysis

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.341 ◽

2016 ◽

Vol 853 ◽

pp. 341-345

Author(s):

Cheng Hong Duan ◽

Li Wei Ding ◽

Ming Wan Lu

Keyword(s):

Cylindrical Shell ◽

Stress Intensity ◽

Stress Analysis ◽

Primary Structure ◽

Pressure Vessel ◽

Elastic Stress ◽

Original Structure ◽

Analysis Method ◽

Stress Classification ◽

Axisymmetric Structure

The implementation of the primary structure method in design by analysis of pressure vessel is discussed. With two examples of axisymmetric structure of pressure vessel, flat head-cylindrical shell joint and flange-ellipsoidal head joint, the primary structure is constructed according to the principle of this method with ANSYS. By comparing the stress intensity and deformation of the primary structure with that of the original structure, the primary and secondary stress along the stress classification line can be clearly distinguished by using the primary structure method. It has great application value in dealing with stress classification in the elastic stress analysis method. The results also show that a variety of reasonable primary structures can be constructed based on the same original structure, and the primary structure method has some flexibility.

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A Comparison Study of Pressure Vessel Design Using Different Standards

Volume 1: Offshore Technology ◽

10.1115/omae2013-10684 ◽

2013 ◽

Author(s):

Frode Tjelta Askestrand ◽

Ove Tobias Gudmestad

Keyword(s):

Stress Analysis ◽

Elastic Stress ◽

Limit Load ◽

Technical Committee ◽

Pressure Vessels ◽

Analysis Method ◽

Elastic Plastic ◽

Load Analysis ◽

American Society ◽

Division 2

Several codes are currently available for design and analysis of pressure vessels. Two of the main contributors are the American Society of Mechanical Engineers providing the ASME VIII code, Ref /4/ and the Technical Committee for standardization in Brussels providing the European Standard, Ref /2/. Methods written in bold letters will be considered in the discussion presented in this paper. The ASME VIII code, Ref /4/, contains three divisions covering different pressure ranges: Division 1: up to 200 bar (3000 psi) Division 2: in general Division 3: for pressure above 690 bar (10000 psi) In this paper the ASME division 2, Part 5, “design by analysis” will be considered. This part is also referred to in the DNV-OS-F101, Ref /3/, for offshore pressure containing components. Here different analysis methods are described, such as: Elastic Stress Analysis Limit Load Analysis Elastic Plastic Analysis The Elastic Stress Analysis method with stress categorization has been introduced to the industry for many years and has been widely used in design of pressure vessels. However, in the latest issue (2007/2010) of ASME VIII div. 2, this method is not recommended for heavy wall constructions as it might generate non-conservative analysis results. Heavy wall constructions are defined by: (R/t ≤ 4) with dimensions as illustrated in Figure 1. In the case of heavy wall constructions the Limit Load Analysis or the Elastic-plastic method shall be used. In this paper focus will be on the Elastic-plastic method while the Limit Load Analysis will not be considered. Experience from recent projects at IKM Ocean Design indicates that the industry has not been fully aware of the new analysis philosophy mentioned in the 2007 issue of ASME VIII div.2. The Elastic Stress Analysis method is still (2012) being used for heavy wall constructions. The NS-EN 13445-3; 2009, Ref /2/, provides two different methodologies for design by analysis: Direct Route Method based on stress categories. The method based on stress categories is similar to the Elastic Stress Analysis method from ASME VIII div. 2 and it will therefore not be considered in this paper.

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Elastic Stress Analysis of a Three-Dimensional Crack Using the Layer Potential : (Indirect Boundary Integral Method)

JSME international journal Ser 1 Solid mechanics strength of materials ◽

10.1299/jsmea1988.31.1_32 ◽

1988 ◽

Vol 31 (1) ◽

pp. 32-37

Author(s):

Michiya KISHIDA ◽

Kazuaki SASAKI ◽

Yukio ISHIDA ◽

Akihiko NOGUCHI

Keyword(s):

Stress Analysis ◽

Integral Method ◽

Elastic Stress ◽

Three Dimensional ◽

Boundary Integral ◽

Boundary Integral Method ◽

Layer Potential

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Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach

Journal of Pressure Vessel Technology ◽

10.1115/1.4001517 ◽

2010 ◽

Vol 132 (3) ◽

Cited By ~ 12

Author(s):

Izumi Nakamura ◽

Akihito Otani ◽

Masaki Shiratori

Keyword(s):

Dynamic Behavior ◽

Failure Modes ◽

Seismic Load ◽

Piping System ◽

Shake Table ◽

Shake Table Tests ◽

Wall Thinning ◽

Piping Systems ◽

Out Of Plane ◽

Plane Bending

Pressurized piping systems used for an extended period may develop degradations such as wall thinning or cracks due to aging. It is important to estimate the effects of degradation on the dynamic behavior and to ascertain the failure modes and remaining strength of the piping systems with degradation through experiments and analyses to ensure the seismic safety of degraded piping systems under destructive seismic events. In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned-wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of the piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned-wall elbow, because the life of the piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

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