Application of Load Release Factor Method in Thermal Expansion Load Imposed on Vessel Nozzle

2021 ◽  
Author(s):  
Xiangbing Zhang ◽  
Chenghong Duan ◽  
Mingwan Lu ◽  
Xiangpeng Luo
Keyword(s):  
Thermal Expansion ◽  
Pressure Vessels ◽  
Release Factor ◽  
Analysis Model ◽  
Theoretical Derivation ◽  
Integrated Method ◽  
Factor Method ◽  
Load Release ◽  
Expansion Load ◽  
Partition Method

Abstract The pressure vessels are connected by pipelines to form a system. Thermal expansion of the pipeline imposes an additional load on the nozzle of the connected vessel. There are two methods to deal with the thermal expansion load of pipeline in the design of pressure vessel: the partition method and the integrated method. A new Load Release Factor Method (LRFM) is proposed in this paper based on theoretical derivation. A spherical head with central nozzle is taken as an FEM (Finite Element Method) analysis model. The results show that a conservative design will be obtained by the traditional partition method, and the integrated method is the closest to the actual situation in spite of the large amount of calculation. However, compared with the traditional two methods, the LRFM can not only ensure the design margin but also reduce the calculation. This paper could be a reference for the analysis of pipeline thermal expansion load in the vessel design.

Investigation on Temperature Compensation of Fiber Bragg Grating Sensors for Hull Monitoring

2018 ◽  
Author(s):  
Ruiqi Ma ◽  
Guoqing Feng ◽  
Huilong Ren ◽  
Peng Fu ◽  
Shuang Wu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Fiber Bragg Grating ◽  
Temperature Compensation ◽  
Compensation Method ◽  
Bragg Grating ◽  
Theoretical Derivation ◽  
Temperature Changes ◽  
Hull Girder ◽  
Fbg Sensor ◽  
Fbg Sensors

Hull monitoring system with Fiber Bragg Grating (FBG) sensors increasingly receives people’s attentions. However, for the ship hull monitoring, the deformation of hull girder changes a lot as is subjected to a huge temperature variation. Therefore, the compensation method with only FBG temperature self-correction is not suitable for the hull monitoring sensors because no material thermal expansion effects are reasonably included. In this paper, the new compensation method of hull monitoring FBG sensor based on the sensor theory with both FBG temperature self-correction and steel thermal expansion effects correction is studied. The coupled compensation method suitable for hull monitoring sensor is obtained by theoretical derivation. As the comparison, the coupled compensation experiment was carried out. The results show that the relative error under the temperature compensation method is large in the case of drastic strain and temperature changes, and the correction results of the tested method will be closer to the true level.

Ratchet Boundary for Superimposed Biaxial Membrane Stress States

2018 ◽  
Author(s):  
Wolf Reinhardt
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Analytical Solution ◽  
Pressure Vessels ◽  
Stress Fields ◽  
Design Codes ◽  
Bending Stress ◽  
Membrane Stress ◽  
Asme Code ◽  
Stress States

Thermal membrane and bending stress fields exist where the thermal expansion of pressure vessel components is constrained. When such stress fields interact with pressure stresses in a shell, ratcheting can occur below the ratchet boundary indicated by the Bree diagram that is implemented in the design Codes. The interaction of primary and thermal membrane stress fields with arbitrary biaxiality is not implemented presently in the thermal stress ratchet rules of the ASME Code, and is examined in this paper. An analytical solution for the ratchet boundary is derived based on a non-cyclic method that uses a generalized static shakedown theorem. The solutions for specific applications in pressure vessels are discussed, and a comparison with the interaction diagrams for specific cases that can be found in the literature is performed.

Design of the Thickness of Hot Corner Protection of LNG Storage Tank

2011 ◽  
Vol 347-353 ◽  
pp. 3777-3780
Author(s):  
Xu Dong Cheng ◽  
Xing Ji Zhu ◽  
Wen Shan Peng
Keyword(s):  
Thermal Stress ◽  
Natural Gas ◽  
Thermal Protection ◽  
Pressure Vessels ◽  
Wall Structure ◽  
Concrete Wall ◽  
Theoretical Derivation ◽  
Finite Element Software ◽  
Special Cases ◽  
Liquid Natural Gas

Large LNG storage tanks as liquid natural gas cryogenic pressure vessels, the cold between the tanks and concrete wall is very important. In some special cases, ultra-low temperature liquefied natural gas will enter the second vessel, then the wall will produce thermal stress, at this time the main factor to control the temperature difference between inside and outside the wall is the hot corner protection. This paper introduces the general international structure of tank insulation, and then through the theoretical derivation, gives the insulating layer, hot corner protection and formula for calculating temperature distribution of exterior wall. On this basis, gives the formula for calculating the external thermal stress and thermal protection angle is given control of the thickness of the design equation. Finally, using ADINA finite element software to establish insulation and the wall temperature field model and calculate the heat - wall structure coupled thermal stress, and through the analysis of a project example to verify the correctness of the formula. The results show that in the leakage state, temperature stress of external wall is large, indicating that it is significant to design the thickness of hot corner protection.

Design and study on the tailorable directional thermal expansion of dual-material planar metamaterial

2019 ◽  
Vol 234 (3) ◽  
pp. 837-846
Author(s):  
Rui Yang ◽  
Qing Yang ◽  
Bin Niu
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Rectangular Lattice ◽  
Design Calculation ◽  
Theoretical Derivation ◽  
Rectangular Cell ◽  
Lattice Materials ◽  
The Matrix ◽  
Simulation And Experiment ◽  
Dual Material

Current studies on tailoring the coefficient of thermal expansion of metamaterials focused on either complex bending-dominated lattice or the stretching-dominated lattice which transforms the spaces of triangle and tetrahedron. This paper proposes a kind of dual-material rectangular cell of tailorable thermal expansion, which reduces the complexities of design, calculation, and manufacture of lattice materials. The theoretical derivation using the matrix displacement method is adopted to study the thermal expansion properties of rectangular cell in the direction of height, the analytical expressions of coefficient of thermal expansion and optimization model are used to design the sizes of rectangular cell, and experimental verification is carried out. It is found that the middle cell of lattice had the same thermal expansion law as that of the unit cell. The rectangular cells of negative coefficient of thermal expansion −7 ppm/℃, zero coefficient of thermal expansion, and large positive coefficient of thermal expansion 36.2 ppm/℃ in the direction of height were realized, respectively. The consistency of theory, simulation, and experiment verifies that rectangular lattice material made of two kinds of common materials with a different coefficient of thermal expansions can achieve the design of coefficient of thermal expansion in the direction of height by choosing different material distribution and geometric parameters.

Effect of Deformation of Core Elements of Fast Reactor Core to the Seismic Response

2019 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Kazuteru Kawamura ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Thermal Expansion ◽  
Fast Reactor ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Reactor Core ◽  
Axial Direction ◽  
Vertical Displacement ◽  
Analysis Model ◽  
The Core ◽  
Core Elements

Abstract Core elements of a fast reactor are self-standing on the core support structure and not restrained in the axial direction. When the earthquake occurs, it is necessary to consider vertical behavior and horizontal displacement of the core elements simultaneously. In the core seismic analysis, a three dimensional core vibration behavior was evaluated by considering fluid structure interaction, collision with adjacent core elements and vertical displacement and verified by a series of vibration tests. But the evaluation had a assumption of straightness of each core elements which may be bowed due to thermal expansion and swelling under restraint of the horizontal direction between the upper pad and lower structure (Entrance Nozzle). If the core elements are deformed in its plant operation, they may push each other against its adjacent core elements. The large horizontal interference forces may work to decrease the vertical displacement of the core elements. In this study, to grasp and estimate the behavior under the deformed core elements under the earthquake motion, a three dimensional seismic analysis model consist of all of core elements with consideration of the effect of deformed core elements were prepared, analyzed and verified by hexagonal-matrix tests with 37 core elements and single row mock-up models with 7 core elements. These test results show that the rising displacements decrease with increased deformation and no rising occurs when the deformations exceed a threshold. In this paper, the effect of bending deformation due to thermal expansion and swelling on the rising displacement of the core elements was shown by seismic experiments.

scholarly journals Research on the influencing factors of thermal characteristics of high-speed grease lubricated angular contact ball bearing

2021 ◽  
Vol 13 (6) ◽  
pp. 168781402110273
Author(s):  
Chang Zhang ◽  
Dan Guo ◽  
Jiyin Tian ◽  
Qingbo Niu
Keyword(s):  
Thermal Expansion ◽  
Heat Generation ◽  
High Speed ◽  
Ball Bearing ◽  
Thermal Characteristics ◽  
Generation Model ◽  
Analysis Model ◽  
Angular Contact Ball Bearing ◽  
Bearing Contact ◽  
Contact Parameters

The high temperature rise of grease lubricated angular contact ball bearing under high speed operation will affect the working accuracy of the bearing, and even lead to the loss of accuracy. In this paper, a friction heat generation model for high-speed grease lubricated angular contact ball bearing was established. Based on the quasi-static analysis model, the thermal expansion of the bearing components is brought into the quasi-static equilibrium equation, and the modified quasi-static analysis model of high-speed grease lubricated ACBB is obtained. Under grease lubrication conditions, a local bearing heat-generation model was employed to assess power losses in different contact zones, in which bearing contact parameters, external loads, and rotation speeds conditions were fully considered. Moreover, the temperature distribution of grease lubricated high-speed bearing was analyzed by the multi node thermal network method. Through the analysis model of bearing dynamic and thermal characteristics considering the influence of thermal expansion established, bearing contact parameters have significant differences. The calculated values of outer ring temperature of grease lubricated angular contact ball bearing is in good agreement with the experimental values. The model can predict the temperature values of grease lubricated angular contact ball bearing under axial load at high speed.

scholarly journals Behaviour of flange joints in Steam Generator under thermal loads

2021 ◽  
Vol 309 ◽  
pp. 01082
Author(s):  
N. Rino Nelson
Keyword(s):  
Thermal Expansion ◽  
Contact Stress ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Pressure Vessels ◽  
Thermal Loads ◽  
Internal Fluid ◽  
Linear Behaviour ◽  
Loading And Unloading ◽  
Differential Thermal Expansion

Pressure vessels such as steam generators are subjected to high temperature, in addition to high pressure during the operating condition. Flanges and bolts are made up of different materials whose coefficient of thermal expansion varies. Usually, thermal expansion in bolts is greater than that of flanges. At elevated temperatures bolts expand more than that of flanges, resulting in decrease of compression in connected members achieved during assembly stage, which in turn decreases the contact stress in gasket. This can lead to leakage of internal fluid. The loss in gasket contact stress due to differential thermal expansion can be nullified by using sleeves of higher thermal expansion between the flange-nut and flange-bolt head interfaces. At higher temperatures sleeves expand more than bolts and flanges, pushing the flanges closer towards each other, thus decreasing gap created due to differential thermal expansion. The behaviour of gasketed blind flange joint with and without sleeves is analysed and the performances are compared under thermal loads. The non-linear behaviour of gaskets is included by specifying the loading and unloading characteristics with hysteresis.

Leak-Before-Break: What Does It Really Mean?

2000 ◽  
Vol 122 (3) ◽  
pp. 267-272 ◽  
Author(s):  
Gery Wilkowski
Keyword(s):  
Thermal Expansion ◽  
Seismic Loading ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Dynamic Event ◽  
Circumferential Crack ◽  
Controlled Conditions ◽  
Oil Pipelines ◽  
High Thermal Expansion ◽  
Leak Before Break

Leak-before-break (LBB) is a term that has been used for decades in reference to a methodology that means that a leak will be discovered prior to a fracture occurring in service. LBB has been applied to missile casings, gas and oil pipelines, pressure vessels, nuclear piping, etc. LBB also has several technical definitions. For instance, LBB can occur for an axial flaw in a pipe where the penetration of the wall thickness will result in a stable axial through-wall crack. This is LBB under load-controlled conditions. LBB could also occur for a circumferential crack in a pipe with high thermal expansion stresses. This might be LBB under compliant displacement-controlled conditions. Finally, LBB might occur when the flaw is stable under normal operating conditions and remains stable when there is a sudden dynamic event (i.e., seismic loading). This might be a time-dependant inertial LBB analysis. These analyses are deterministic, and could be extended to probabilistic evaluations as well. This paper describes some of the technical LBB approaches, applications, and significance of the methodology used in the applications. [S0094-9930(00)01603-6]

Stress and Fracture Analysis of Ceramic Lined, Composite or Steel Jacketed Pressure Vessels

2004 ◽  
Vol 126 (4) ◽  
pp. 485-488 ◽  
Author(s):  
John H. Underwood ◽  
Anthony P. Parker
Keyword(s):  
Fracture Toughness ◽  
Thermal Expansion ◽  
Room Temperature ◽  
Fracture Analysis ◽  
Pressure Vessels ◽  
Interface Pressure ◽  
Temperature Stresses ◽  
Critical Crack ◽  
Steel Jacket ◽  
Differential Thermal Expansion

Stress and fracture analysis of ceramic-lined cannon pressure vessels is described, for a Si3N4 or SiC liner and A723 steel or carbon-epoxy jacket and with an initial residual interface pressure between liner and jacket and pressure applied to the bore. Room temperature stresses for a steel jacket over ceramic are similar to those for a carbon-epoxy jacket, but both radial and hoop jacket stresses can exceed typical carbon-epoxy strength values. Elevated temperature liner stresses are reduced for a carbon-epoxy jacket, due to the effective increase in interface pressure caused by differential thermal expansion. Critical crack sizes for brittle fracture are generally very small, albeit larger for Si3N4 than SiC due to lower liner stresses and higher fracture toughness for Si3N4.

An Improved Design of Threaded Closures for Screw Plug (Breech Lock) Heat Exchangers

2016 ◽  
Author(s):  
Haresh K. Sippy ◽  
Dipak K. Chandiramani
Keyword(s):  
Thermal Expansion ◽  
Heat Exchangers ◽  
Tube Bundle ◽  
Pressure Vessels ◽  
Typical Application ◽  
Heat Transfer Efficiency ◽  
Shrink Fitting ◽  
Shell And Tube ◽  
Improved Design ◽  
Screw Threads

Threaded closures for pressure vessels have been in use for decades. Much work has been done to develop convenient, safe and economical threaded closures. Threaded closures are used when there is a need for opening the vessel either for maintenance or as part of its operation. Heat Exchangers are a typical application where there is a need for opening the vessel and cleaning the tubes at regular intervals to maintain the heat transfer efficiency. These are known as Breech Lock or Screw Plug Exchangers. These are basically U-tube exchangers. The channel side operates at high temperature and pressure and it has a threaded end closure. In some designs, the shell side may also be at high pressure. The tube bundle is removable without having to dismantle the channel or disconnect the nozzles from the pipeline. Thus screw plug exchangers help to reduce fabrication cost and reduce time for in-service maintenance. The major problem encountered with the use of such end closures are 1) Jamming of the threaded plug, due to deformation of the channel barrel. Thus the opening of the end closure by unscrewing becomes a difficult task. With the increase in operating temperatures and pressures, the problems become more severe, due to which, users are not inclined to use these type of end closures. A study was undertaken to assess the reasons for bulging of the end of the channel which caused jamming of the screw threads and also for leakage through the gasket. By shrink fitting a ring over the end of the channel, the deformation was reduced, enabling easy opening of the cover. 2) The leakage through the gasket between the shell and tubesheet, causing the intermixing of shell and tube-side fluids. This on analysing was found that the additional forces were acting on the gasket due to thermal expansion of the internals. This led to changing to a gasket that could withstand the forces and pressure. Leakage through the gasket was prevented by analysing the additional forces acting on the gasket due to thermal expansion of the internals and changing to a gasket that could withstand the forces and pressure.

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