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.

Thermal Expansion of Polyether Ether Ketone Bearing Components

2019 ◽  
Vol 64 (4) ◽  
pp. 1-5 ◽  
Author(s):  
Bryan D. Allison ◽  
Connor M. Vanderwiel
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Aerospace Applications ◽  
Polyether Ether Ketone ◽  
Molded Parts ◽  
Injection Molded ◽  
Ether Ketone ◽  
Bearing Design ◽  
Strong Candidate

Carbon fiber–reinforced polyether ether ketone (PEEK) is a strong candidate for aerospace bearing cages due to its low density and good mechanical properties. However, there are still concerns regarding its performance at the elevated temperatures seen in aerospace applications. In particular, an accurate measurement of PEEK's coefficient of thermal expansion (CTE) is critical to proper bearing design. In this paper, the CTE of as-manufactured PEEK cages was measured to determine the range of CTE that can be expected for production parts. A range of cage sizes and designs were considered in this study. Components that were manufactured from stock shapes through subtractive methods were studied in addition to components made via injection molding. The CTE of machined PEEK was found to be significantly higher than that of injection-molded PEEK and also varied significantly from part to part. In contrast, the CTE of molded PEEK cages was found to be fairly consistent between parts. Finally, the CTE of PEEK was found to increase above the glass transition temperature of 143 °C, but it was demonstrated that this increase is relatively small for injection-molded parts.

Thermal Shrinkage Behavior of Battery Separator

2018 ◽  
Author(s):  
Shutian Yan ◽  
Jie Deng ◽  
Chulheung Bae ◽  
Xinran Xiao
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Porous Membrane ◽  
Thermal Shrinkage ◽  
Dynamic Mechanical Analyzer ◽  
Free Standing ◽  
Dynamic Mechanical ◽  
Battery Separator ◽  
Shrinkage Behavior

Battery separators are thin, porous membrane of 20∼30 microns thickness. Polymer separators display a significant amount of shrinkage at elevated temperatures. It is difficult to quantitatively characterize the large shrinkage behavior with a free standing separator sample. This paper examines the use of a dynamic mechanical analyzer under tensile mode in measuring the coefficient of thermal expansion (CTE) of three commonly used separators.

Effect of aggregate type on linear thermal expansion of self-consolidating concrete at elevated temperatures

2012 ◽  
Vol 19 (3) ◽  
pp. 259-269 ◽  
Author(s):  
Tayfun Uygunoğlu ◽  
İlker Bekir Topçu
Keyword(s):  
Thermal Expansion ◽  
Thermal Properties ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Thermal Tests ◽  
Linear Change ◽  
Volcanic Tuff ◽  
Self Consolidating Concrete ◽  
Cement Ratio

AbstractIn this study, the effects of aggregate type on the coefficient of thermal expansion of self-consolidating concrete (SCC) produced with normal and lightweight (porous) aggregate (SCLC) were investigated. In experiments, three aggregate types, gravel, volcanic tuff, and diatomite, were used. Different combinations of water/cement ratio and superplasticizer dosage levels were prepared for the SCC and SCLC mixtures. Thermal tests were performed to accurately characterize the coefficient of thermal expansion (CTE) of SCC and SCLC aged 28 days using the dilatometer. The CTEs of SCC and SCLC were defined by measuring the linear change in length of concrete specimens subjected to a range of temperatures from 20°C to 1000°C. The results, in general, showed that SCLC has a lower CTE than that of SCC above 100°C. Moreover, CTE values of SCC and SCLC were decreased with increase in porous structure. The aggregate type has significant influence on the thermal properties of SCC.

A Study on the Behavior of Single- and Twin-Gasketed Flange Joint Under External Bending Load

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
N. Rino Nelson ◽  
N. Siva Prasad ◽  
A. S. Sekhar
Keyword(s):  
Finite Element ◽  
Elevated Temperatures ◽  
Bending Moment ◽  
Pressure Vessels ◽  
Hysteretic Behavior ◽  
Bending Test ◽  
Flange Joint ◽  
Internal Fluid ◽  
Bending Load ◽  
Gasket Material

Gasketed flange joints are widely used in pressure vessels and piping systems. They are subjected to bending load due to differential thermal expansion, wind load, self-weight, etc., in addition to assembly and internal fluid load. Most of the flange designs are based on equivalent pressure method to include the effect of external bending loads. The behavior of gasketed flange joint is complex due to the nonlinear hysteretic behavior of gasket material and contact interfaces between joint members. It becomes more complex when the joint is subjected to bending load at elevated temperatures. In the present work, performance of a flange joint has been studied under internal pressure and external bending load at elevated temperatures. A 3D finite element model is developed, considering the nonlinearities in the joint due to gasket material and contact between its members along with their temperature-dependent material properties. The performance of joint under different bolt preloads, internal fluid pressures, and temperatures is studied. Flange joint with two gaskets (twin-gasketed flange joint, TGJ) placed concentric is also analyzed. The results from finite element analysis (FEA) are validated using four-point bending test on gasketed flange joint. The sealing and strength criteria are considered to determine the maximum allowable bending moment at different internal fluid temperatures, for both single- and twin-gasketed flange joints with spiral wound gasket. Twin gasket is able to withstand higher bending moment without leakage compared to single gasket. Results show that the allowable load on flange joint depends on operating temperature and gasket configuration.

scholarly journals Preparation and Properties of Inherently Black Polyimide Films with Extremely Low Coefficients of Thermal Expansion and Potential Applications for Black Flexible Copper Clad Laminates

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 576 ◽  
Author(s):  
Yao-yao Tan ◽  
Yan Zhang ◽  
Gang-lan Jiang ◽  
Xin-xin Zhi ◽  
Xiao Xiao ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Dimensional Stability ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Optical Transmittance ◽  
Molecular Structures ◽  
Molar Ratio ◽  
Optical Parameters ◽  
Aromatic Diamines ◽  
Potential Applications

In the current work, a series of black polyimide (PI) films with excellent thermal and dimensional stability at elevated temperatures were successfully developed. For this purpose, two aromatic diamines including 4,4′-iminodianline (NDA) and 2-(4-aminophenyl)-5- aminobenzimidazole (APBI) were copolymerized with pyromellitic dianhydride (PMDA) to afford PIs containing imino groups (–NH–) in the molecular structures. The referenced PI film, PI-ref, was simultaneously prepared from PMDA and 4,4′-oxydianiline (ODA). The introduction of imino groups endowed the PI films with excellent blackness and opaqueness with the optical transmittance lower than 2% at the wavelength of 600 nm at a thickness of 25 μm and lightness (L*) below 10 for the CIE (Commission International Eclairage) Lab optical parameters. Meanwhile, the introduction of rigid benzimidazole units apparently improved the thermal and dimensional stability of the PI films. The PI-d film based on PMDA and mixed diamines (NDA:APBI = 70:30, molar ratio) showed a glass transition temperature (Tg) of 445.5 °C and a coefficient of thermal expansion (CTE) of 8.9 × 10−6/K in the temperature range of 50 to 250 °C, respectively. It is obviously superior to those of the PI-a (PMDA-NDA, Tg = 431.6 °C; CTE = 18.8 × 10−6/K) and PI-ref (PMDA-ODA, Tg = 418.8 °C; CTE: 29.5 × 10−6/K) films.

Variation of lattice parameter and coefficient of thermal expansion of Mnln2S4 at elevated temperatures

1987 ◽  
Vol 6 (4) ◽  
pp. 489-490 ◽  
Author(s):  
V. Bhaskara Sastry ◽  
B. Appa Rao ◽  
P. V. Mohan Rao ◽  
K. Satyanarayana Murthy
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Parameter

Thermal expansion and pore pressure generation in oil sands

1986 ◽  
Vol 23 (3) ◽  
pp. 327-333 ◽  
Author(s):  
J. G. Agar ◽  
N. R. Morgenstern ◽  
J. D. Scott
Keyword(s):  
Thermal Expansion ◽  
Pore Pressure ◽  
Oil Sands ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Oil Sand ◽  
Thermal Expansion Coefficients ◽  
Stress Changes ◽  
Expansion Coefficients

The prediction of stress changes and deformations arising from ground heating requires the coupled solution of the heat transfer and consolidation equations. Heat consolidation as a class of problems is distinct from other thermally induced consolidation problems involving processes such as frost heave and thaw consolidation in that it involves heating to elevated temperatures well above normal ground temperatures. Two of the important parameters required in analyses of heat consolidation problems are thermal expansion coefficients and a coefficient of thermal pore pressure generation.Relationships describing thermal expansion behaviour and thermal pore pressure generation in oil sands are presented. Both drained and undrained thermal expansion coefficients for Athabasca oil sand were determined by means of heating experiments in the temperature range 20–300 °C. The thermal pore pressure generation coefficient was evaluated in undrained heating experiments under constant total confining stresses and under constant effective confining stresses. The equipment and experimental methods developed during this study are appropriate for determination of thermal expansion and pore pressure generation properties of oil sands and other unconsolidated geologic materials. Key words: thermal expansion, oil sand, tar sand, thermal pore pressure generation, heat consolidation, thermal consolidation, coefficient of thermal expansion, thermal stresses, ground heating, thermally enhanced oil recovery, thermoelasticity, undrained heating.

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.

ALCAN 162

Alloy Digest ◽  
1964 ◽  
Vol 13 (12) ◽  
Keyword(s):  
Thermal Expansion ◽  
Corrosion Resistance ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Heat Treating ◽  
Casting Alloy ◽  
Permanent Mold ◽  
Temperature Performance ◽  
Aluminum Company ◽  
Mold Casting

Abstract Alcan 162 is an aluminum permanent mold casting alloy having low coefficient of thermal expansion, good wearing characteristics and retention of strength at elevated temperatures. It is age hardenable. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-142. Producer or source: Aluminum Company of Canada Ltd.

Effect of elevated temperatures and applied pressure on the tribological properties of LM30/sillimanite aluminium alloy composites

2018 ◽  
Vol 53 (11) ◽  
pp. 1521-1539 ◽  
Author(s):  
Sandeep Sharma ◽  
Tarun Nanda ◽  
OP Pandey
Keyword(s):  
Thermal Expansion ◽  
Cast Iron ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Operating Temperature ◽  
Low Cost ◽  
Applied Pressure ◽  
Reinforcement Particle ◽  
Aluminum Matrix Composites ◽  
Brake Rotor

The present study focuses on the development of low-cost, lightweight and highly wear resistant composites for brake rotor applications. Sillimanite mineral reinforced aluminum matrix composites were stir cast using three distinct reinforcement particle sizes. Reinforcement level was varied in the range of 3–15 wt%. The influence of operating temperature (50℃–300℃) and applied pressure (0.2–1.0 MPa) on the wear/friction behaviour of composites was observed. Optical micrographs showed homogenous particle distribution throughout the matrix. The high nanohardness obtained for interface regions signifies good particle–matrix bonding of processed composites. Dilatometry studies showed that the increase in sillimanite content decreased the coefficient of thermal expansion of the composites. Maximum improvement of 33% in coefficient of thermal expansion (over base alloy) was observed for 15 wt% fine composites. Wear analysis revealed that the developed composites provided adequate wear resistance till an operating temperature of 200℃, beyond which wear rate increased significantly. For the high operating temperature of 200℃, the steady-state wear of composites was comparable (only 6.62% higher) to the commercial cast iron alloy used in brake rotor applications. The aluminium-based composites developed in the present research are low cost (sillimanite is a naturally occurring mineral sand) and lightweight (60% lighter than cast iron) and can be used as an alternate material for brake rotors in light vehicles. Finally, SEM of worn out surfaces divulged the dominance of adhesive wear for material removal.

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