Estimation Method for First Excursion Probability of System With Collision Characteristic

2006 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Failure Modes ◽  
Estimation Method ◽  
Pressure Vessels ◽  
Expected Value ◽  
Maximum Response ◽  
Seismic Excitations ◽  
Nonlinear Characteristics ◽  
Tolerance Level ◽  
Piping Systems ◽  
Excursion Probability

Safety of structures subjected to seismic excitations should be evaluated in probabilistic manner. First excursion failure is one of the most important failure modes of structures. Many structures have nonlinear characteristics. Collision characteristic is one of the most common nonlinear characteristics observed in pressure vessels and piping systems. In this paper, an estimation method for the first excursion probability of structure with collision characteristic is proposed. The first excursion probability is the function of many parameters. It is shown that when the tolerance level is normalized by the expected value of the maximum response of the structures, the first excursion probability can be shown to be in dependent of many parameters.

Reliability of System With Hysteresis Loop Characteristic Subjected to Earthquake Excitations

2007 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Hysteresis Loop ◽  
Failure Modes ◽  
Estimation Method ◽  
Pressure Vessels ◽  
Nonlinear Characteristics ◽  
Tolerance Level ◽  
Piping Systems ◽  
Time Histories ◽  
Expected Values ◽  
Excursion Probability

Estimation of reliability of system subjected to earthquake excitations is important problem for aseismic design. Reliability of such system should be evaluated in probabilistic manner. First excursion failure is one of the most important failure modes of structures and one of a factor of reliability. Many structures have nonlinear characteristics. Hysteresis loop characteristic caused by plastic deformation is one of the most common nonlinear characteristics observed in pressure vessels and piping systems. In this paper, an estimation method for the first excursion probability of structure with hysteresis loop characteristic is proposed. The first excursion probability is the function of many parameters. First excursion probability is obtained by using artificial time histories. It is shown that when the tolerance level is normalized by the expected values of the maximum response of the structures, the first excursion probability can be shown independent of many parameters.

Reliability of System With Hysteresis Loop Characteristic Subjected to Earthquake Excitations

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Hysteresis Loop ◽  
Failure Modes ◽  
Estimation Method ◽  
Pressure Vessels ◽  
Nonlinear Characteristics ◽  
Tolerance Level ◽  
Piping Systems ◽  
Time Histories ◽  
Expected Values ◽  
Excursion Probability

The estimation of reliability of system subjected to earthquake excitations is an important problem for aseismic design. The reliability of such system should be evaluated in probabilistic manner. The first excursion failure is one of the most important failure modes of structures and also one factor of reliability. Many structures have nonlinear characteristics. Hysteresis loop characteristic caused by plastic deformation is one of the most common nonlinear characteristics observed in pressure vessels and piping systems. In this paper, an estimation method for the first excursion probability of structure with hysteresis loop characteristic is proposed. The first excursion probability is the function of many parameters, which is obtained by using artificial time histories. It is shown that when the tolerance level is normalized by the expected values of the maximum response of the structures, the first excursion probability can be shown to be independent of many parameters.

An Estimation Method for First Excursion Probability of Nonlinear System Using Maximum Response

2004 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Failure Modes ◽  
Damping Ratio ◽  
Estimation Method ◽  
Maximum Response ◽  
Estimation Methods ◽  
Mechanical Equipment ◽  
Primary System ◽  
Secondary System ◽  
Restoring Force ◽  
Excursion Probability

The secondary system such as pipings, tanks and other mechanical equipment are installed in the primary system such as building. The important secondary systems should be designed to maintain their function even if they are subjected to destructive earthquake excitations. First excursion failure is one of the most important failure modes. The secondary system has many nonlinear characteristics. In this paper, an estimation methods of the first excursion probability of the secondary system with gap and friction subjected to earthquake excitation is proposed. Restoring force with gap and friction force is equivalently linearized. When the tolerance level is normalized by the maximum response of the secondary system without gap and friction characteristics, variation of the first excursion probability is very small for various values of mass ratio of the secondary system to the primary system, the damping ratio and the natural period.

Nonlinear Analysis in Pressure Vessel Design Codes: Recommendations for Codified Rules Improvements

2018 ◽  
Author(s):  
Claude Faidy
Keyword(s):  
Material Properties ◽  
Failure Modes ◽  
Plastic Instability ◽  
Pressure Vessels ◽  
Inelastic Analysis ◽  
Stress Classification ◽  
Piping Systems ◽  
Plastic Shakedown ◽  
Stress Criteria

During the past 30 years the main rules to design pressure vessels were based on elastic analyses. Many conservatisms associated to these different elastic approaches are discussed in this paper, like: stress criteria linearization for 3-D components, stress classification in nozzle areas, plastic shake down analysis, fatigue analysis, Ke evaluation, and pipe stress criteria for elastic follow-up due to thermal expansion or seismic loads... This paper will improve existing codified rules in nuclear and non-nuclear Codes that are proposed as alternatives to elastic evaluation for different failure modes and degradation mechanisms: plastic collapse, plastic instability, tri-axial local failure, rupture of cracked component, fatigue and Ke, plastic shakedown. These methods are based on limit loads, monotonic or cyclic elastic-plastic analyses. Concerned components are mainly vessels and piping systems. No existing Code is sufficiently detailed to be easily applied; the needs are stress analysis methods through finite elements, material properties including material constitutive equations and criteria associated to each methods and each failure modes. A first set of recommendation to perform these inelastic analysis will be presented to improve existing codes on an international harmonized way, associated to all material properties and criteria needed to apply these modern methods. An international draft Code Case is in preparation.

Stress of Large Diameter Piping System Shoe Support

2017 ◽  
Author(s):  
Sadjad Ranjbaran ◽  
Akbar Daneshvar Ghalelar
Keyword(s):  
Failure Modes ◽  
Large Diameter ◽  
Estimation Method ◽  
Beam Theory ◽  
Local Stress ◽  
Accurate Estimation ◽  
Piping System ◽  
Element Analysis ◽  
Piping Systems ◽  
Applied Design

As codes and standards employ the beam theory to evaluate stress in piping systems, large diameter piping is therefore outside the domain of these codes and standards. To investigate any failure modes in these piping systems, more general codes such as ASME Sec. VIII Div.2 must be used. Research has shown that estimating local stress is important near the shoe support tip especially for large diameter piping systems and aboveground pipelines. To evaluate protection against local failure under an applied design load, a more accurate estimation method of ASME Sec. VIII Div.2, part 5 is applied by using elastic-plastic stress analysis procedures. For this purpose, finite element analysis is carried out along with distributed gravity loading and design pressure. Furthermore, parametric FEA studies are conducted on the effect of the ratio of pipe diameter to thickness, as well as the width and wrap angle of shoe support on the local stress of shoe support. The FEA results have been compared to semi-empirical formula for local stress in shoe support developed by AWWA standard.

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

2010 ◽  
Vol 132 (3) ◽  
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.

Safety Assessment of Long Term Serviced Pressure Vessels: A Case Study of Typical Refining and Chemical Plants in China

2021 ◽  
Author(s):  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Haiyi Jiang ◽  
Xiaowei Li
Keyword(s):  
Pressure Vessel ◽  
Safety Assessment ◽  
Failure Modes ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Chemical Plants ◽  
Safety Specification ◽  
Detailed Assessment

Abstract The safety and risk of the long term serviced pressure vessels, especially which serviced more than 20 years, has become one of the most concerned issues in refining and chemical industry and government safety supervision in China. According to the Chinese pressure vessel safety specification TSG 21-2016 “Supervision Regulation on Safety Technology for Stationary Pressure Vessel”, if necessary, safety assessment should be performed for the pressure vessel which reaches the design service life or exceeds 20 years without a definite design life. However, the safety and risk conditions of most pressure vessels have little changes after long term serviced because their failure modes are time-independent. Thus the key problem is to identify the devices with the time-dependent failure modes and assess them based on the failure modes. This study provided a case study on 16 typical refining and chemical plants including 1870 pressure vessels serviced more than 20 years. The quantitative risk and damage mechanisms were calculated based on API 581, the time-dependent and time-independent failure modes were identified, and the typical pressure vessels were assessed based on API 579. Taking the high pressure hydrogenation plant as an example, this study gave the detailed assessment results and conclusions. The results and suggestions in this study are essential for the safety supervision and extending life of long term serviced pressure vessels in China.

Experimental Assessment of the Dynamic Behavior of Polyolefin Thermoplastic Hot Melt Adhesive

2018 ◽  
Author(s):  
Raffaele Ciardiello ◽  
Andrea Tridello ◽  
Luca Goglio ◽  
Giovanni Belingardi
Keyword(s):  
Failure Modes ◽  
Industrial Applications ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Dynamic Tests ◽  
Cohesive Failure ◽  
Static Tests ◽  
Piping Systems ◽  
The Many ◽  
Hot Melt

In the last decades, the use of adhesives has rapidly increased in many industrial fields. Adhesive joints are often preferred to traditional fasteners due to the many advantages that they offer. For instance, adhesive joints show a better stress distribution compared to the traditional fasteners and high mechanical properties under different loading conditions. Furthermore, they are usually preferred for joining components made of different materials. A wide variety of adhesives is currently available: thermoset adhesives are generally employed for structural joints but recently there has been a significant increment in the use of thermoplastic adhesives, in particular of the hot-melt adhesives (HMAs). HMAs permit to bond a large number of materials, including metal and plastics (e.g., polypropylene, PP), which can be hardly bonded with traditional adhesives. Furthermore, HMAs are characterized by a short open time and, therefore, permit for a quick and easy assembly process since they can be easily spread on the adherend surfaces by means of a hot-melt gun and they offer the opportunity of an ease disassembling process for repair and recycle. For all these reasons, HMAs are employed in many industrial applications and are currently used also for bonding polypropylene and polyolefin piping systems. In the present paper, the dynamic response of single lap joints (SLJ) obtained by bonding together with a polyolefin HMA two polypropylene substrates was experimentally assessed. Quasi-static tests and dynamic tests were carried out to investigate the strain rate effect: dynamic tests were carried out with a modified instrumented impact pendulum. Relevant changes in the joint performance have been put in evidence. Failure modes were finally analysed and compared. A change in the failure mode is experimentally found: in quasi-static tests SLJ failed due to a cohesive failure of the adhesive, whereas in dynamic tests the SLJ failed due to an interfacial failure, with a low energy absorption.

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

2007 ◽  
Author(s):  
Satoshi Tsunoi ◽  
Akira Mikami ◽  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Analytical Model ◽  
Failure Modes ◽  
Experimental Investigations ◽  
Seismic Load ◽  
Piping System ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Seismic Loadings ◽  
Local Wall Thinning

The authors have proposed an analytical model by which they can simulate the dynamic and failure behaviors of piping systems with local wall thinning against seismic loadings. In the previous paper [13], the authors have carried out a series of experimental investigations about dynamic and failure behaviors of the piping system with fully circumferential 50% wall thinning at an elbow or two elbows. In this paper these experiments have been simulated by using the above proposed analytical model and investigated to what extent they can catch the experimental behaviors by simulations.

Integrity Assessment of Pressure Components With Local Hot Spots

2005 ◽  
Vol 127 (2) ◽  
pp. 137-142 ◽  
Author(s):  
R. Seshadri
Keyword(s):  
Hot Spots ◽  
Structural Integrity ◽  
Refractory Lining ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Industrial Processes ◽  
Integrity Assessment ◽  
Piping Systems ◽  
Further Development ◽  
Level 2

Local hot spots can occur in some pressure vessels and piping systems used in industrial processes. The hot spots could be a result of, for instance, localized loss of refractory lining on the inside of pressure components or due to a maldistribution of process flow within vessels containing catalysts. The consequences of these hot spots on the structural integrity of pressure components are of considerable importance to plant operators. The paper addresses structural integrity issues in the context of codes and standards design framework. Interaction of hot spots, as is the case when multiple hot spots occur, is addressed. An assessment method, suitable for further development of a Level 2 “Fitness-for-Service” methodology, is discussed and applied to a commonly used pressure component configuration.

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