Effect of Creep of Non-Asbestos Sheet Gaskets at Elevated Temperature on Relaxation Behavior of Bolted Flange Joints

2011 ◽  
Author(s):  
Atsushi Yamaguchi ◽  
Takashi Honda ◽  
Masahiro Hagihara ◽  
Hirokazu Tsuji
Keyword(s):  
Elevated Temperature ◽  
Creep Strain ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Relaxation Behavior ◽  
Test Conditions ◽  
Internal Fluid ◽  
Fiber Sheet ◽  
Ptfe Sheet ◽  
Bolted Flange

Gaskets in bolted flange joints experience creep when used for long periods of time. Since gaskets are often used at elevated temperatures, the clarification of their high-temperature creep behavior is essential. Relaxation of bolted flange joints is caused by creep in the gaskets, and may result in leakage of internal fluids. Therefore, the ability to predict relaxation in bolted flange joints due to the effects of creep in gaskets would allow the lifetime of the gaskets to be estimated and thus prevent leakage of internal fluid. In the present study, the creep behavior of non-asbestos sheet gaskets and the relaxation behavior of these gaskets in bolted flange joints at room/elevated temperature were investigated using four-inch flanges. The test conditions were 180 °C for 360 hours (approximately 2 weeks). The test samples were four types of non-asbestos sheet gaskets, two types of compressed fiber sheet gaskets and two types of PTFE sheet gaskets. The differences in creep behavior between the two types of compressed fiber sheet gaskets and between the two types of PTFE sheet gaskets were clarified. The creep strain at the end of the test was always larger than that just after reaching the test temperature for all gasket materials. On the other hand, the creep strain in the PTFE sheet gaskets just after reaching the elevated temperature was approximately equivalent to the total creep strain after the test has been completed. Thus, the creep behavior of each test gaskets was clarified under aging. In addition, the time for replacement of gaskets was estimated using the relaxation behavior in bolted flange joints by defining the time to reach the minimum design seating stress of the test gasket.

Evaluation of Creep Properties of Non-Asbestos Joint Sheet Gaskets at Elevated Temperature by Three-Dimensional Viscoelasticity Model

2008 ◽  
Author(s):  
Atsushi Yamaguchi ◽  
Hirokazu Tsuji
Keyword(s):  
Elevated Temperature ◽  
Volume Change ◽  
Stress Reduction ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Chemical Factor ◽  
Creep Properties ◽  
Test Conditions ◽  
Internal Fluid

When the gasket in a flange joint is used over the long term at an elevated temperature, the gaskets experience creep/relaxation. The creep of the gaskets may cause leakage of the internal fluid. Many gaskets are used at elevated temperatures, so the clarification of their creep properties at elevated temperatures is urgently needed. The creep of non-asbestos gaskets at an elevated temperature was tested using four-inch flanges and compressed non-asbestos joint sheet gaskets. The test conditions are 180°C and 500 hours. A three-dimensional viscoelasticity model that yields more accurate results compared to the viscoelasticity model, which uses the conventional single axis, was applied to the elevated temperature creep properties. Using the three-dimensional viscoelasticity model, the gasket creep is divided into the viscoelasticity component that converges on a certain strain and the volume change component that increases with time. The gasket strain is evaluated by the three-dimensional viscoelasticity model that considers the stress reduction. It is shown that the gasket strain is divided into the pure creep component of the gasket and the volume change due to the weight loss and chemical factor.

Creep-Relaxation Modeling of HDPE and Polyvinyl Chloride Bolted Flange Joints

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Rahul Palaniappan Kanthabhabha Jeya ◽  
Zijian Zhao ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Polyvinyl Chloride ◽  
Creep Behavior ◽  
Creep Property ◽  
Dissimilar Materials ◽  
Operating Conditions ◽  
Relaxation Behavior ◽  
Polymer Materials ◽  
Creep Model ◽  
Tension And Compression ◽  
Bolted Flange

Abstract Similar to many polymer materials, high-density polyethylene (HDPE) and polyvinyl chloride (PVC) show a clear creep behavior, the rate of which is influenced by temperature, load, and time. Most bolted flange joints undergo relaxation under compression, which is caused by the creep of the material. However, the creep property of the two polymers is different under tension and compression loading. Since the sealing capacity of a flanged gasketed joint is impacted by the amount of relaxation that takes place, it is important to properly address and predict the relaxation behavior due to flange creep under compression and thereby reducing the chances of leakage failure of HDPE and PVC bolted flange joints. The main objective of this study is to analyze the compressive creep behavior of HDPE and PVC flanges under normal operating conditions. This is achieved by developing a respective creep model for the two materials, based on their short-term experimental creep test data. Both numerical and experimental simulations of the polymeric flange relaxation behavior are conducted on an NPS 3 class 150 bolted flange joint of dissimilar materials, where one of the flanges is made of HDPE or PVC material and the other one is made of steel SA105. The study also provides a clear picture on how the compression creep data of ring specimen may be utilized for predicating the flange bolt load relaxation over time at the operating temperatures.

Effect of Hydrogen on Creep Behavior of a Vanadium-Modified CRMO Steel and its Continuum Damage Analysis

2018 ◽  
Author(s):  
Yu Zhou ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Peng Xu ◽  
Xiaoliang Liu
Keyword(s):  
Constitutive Model ◽  
Creep Strain ◽  
Creep Behavior ◽  
Hydrogen Pressure ◽  
Damage Mechanics ◽  
Elevated Temperatures ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Methane Pressure ◽  
Crmo Steel

Creep properties both in hot hydrogen and in air of a vanadium-modified CrMo steel 2.25Cr1Mo0.25V, widely used in hydroprocessing reactors in petrochemical industry, were investigated to determine the effect of hydrogen on high-temperature creep behavior of the low-alloy ferritic steel. The minimum creep strain rate in hydrogen is higher than that in air, whereas the creep strain at failure in hydrogen is relatively smaller. Many tiny spherical cavities are dispersively distributed in the ruptured specimen under hydrogen, which has relatively higher Vickers hardness. Based on the thermodynamics theory, the pressure of methane generated by the so-called “methane reaction” in the vanadium-modified CrMo steel can be calculated by using corresponding thermodynamic data, assuming that methane can reach its equilibrium state during cavitation. Meanwhile, a creep constitutive model based on continuum damage mechanics (CDM) was proposed, taking methane pressure into consideration. The results show that methane pressure increases nonlinearly with increase of hydrogen pressure while it decreases gradually with increase of temperature. The constitutive model considering the damage induced by methane pressure can be used to predict the effect of hydrogen pressure and temperature on creep life, indicating that the influence of hydrogen at elevated temperatures becomes smaller when increasing temperature or decreasing hydrogen pressure.

Creep Modeling of Polyvinyl Chloride Bolted Flange Joints

2017 ◽  
Author(s):  
Zijian Zhao ◽  
Rahul Palaniappan Kanthabhabha Jeya ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Polyvinyl Chloride ◽  
Creep Behavior ◽  
Compressive Load ◽  
Dissimilar Materials ◽  
Operating Conditions ◽  
Relaxation Behavior ◽  
Creep Model ◽  
Compression Creep ◽  
Material Creep ◽  
Bolted Flange

Alike other polymer material, PolyVinyl Chloride (PVC) shows a clear creep behavior, the rate of which is influenced by temperature, load and time. Polyvinyl chloride bolted flange joints undergo relaxation under compression for which the material creep properties are different than those under tension. Since the sealing capacity of a flanged gasketed joint is impacted by the amount of relaxation that takes place, it is important to properly address and predict the relaxation behavior due to flange creep under compression and reduce the chances of leakage failure of PVC flange joints. The main objective is study the creep behavior of PVC flanges under the influence of normal operating conditions. This is achieved by developing a PVC creep model based on creep test data under various compressive load, temperature and time. A simulation of a PVC flange relaxation behavior bot numerically and experimentally is conducted on an NPS 3 class 150 bolted flange joint of dissimilar materials one made of PVC material and the other one by steel SA105. The study also provides a clear picture on how the compression creep data on Ring specimen may be utilized for predicating the flange performance under various operating temperatures with time.

Prediction of Relaxation Property for Long Term in Bolted Flange Joints Based on Viscoelasticity Model of Gasket

2010 ◽  
Author(s):  
Atsushi Yamaguchi ◽  
Hirokazu Tsuji ◽  
Takashi Honda
Keyword(s):  
Finite Element ◽  
Stress Relaxation ◽  
Internal Pressure ◽  
Creep Strain ◽  
Relaxation Behavior ◽  
Test Method ◽  
Fe Model ◽  
Strain Behavior ◽  
Bolted Flange

Creep/relaxation occurs when gaskets for bolted flange joints are used over extended periods. Creep/relaxation of gaskets may cause leakage of an internal fluid from the joints. In order to prevent leakage of a contained fluid from flange joints, it is important to establish a method for the prediction of gasket creep or stress relaxation. In the present study, the relaxation behavior of the axial bolt force was measured in order to estimate creep/relaxation of gaskets by referencing the ASTM F-38 test method [1]. The tests were accomplished at room temperature over a period of 240 hours (10 days). The strain behavior of gaskets was obtained using the viscoelasticity model and the finite element (FE) model of the test equipment based on the ASTM F-38 test method. In addition, the creep strain behavior of gaskets obtained through finite element analysis (FEA) and applied to gaskets in the FE model of the bolted flange joints, and the stress relaxation in the bolted flange joints were estimated over the long term. In the FEA of the bolted flange joints, the relaxation behavior of the axial bolt force that includes internal pressure load was predicted using the creep strain behavior of the gasket. Then, the radial gasket stress is investigated for tightening, for internal pressure load and for stress relaxation. It was found that the radial stress of the gaskets approaches uniformity, and the effect of flange rotation in the bolted flange joint decreases due to the creep strain behavior of the gaskets.

scholarly journals Experimental Investigation on the In-Plane Creep Behavior of a Carbon-Fiber Sheet Molding Compound at Elevated Temperature at Different Stress States

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2545
Author(s):  
David Finck ◽  
Christian Seidel ◽  
Anika Ostermeier ◽  
Joachim Hausmann ◽  
Thomas Rief
Keyword(s):  
Elevated Temperature ◽  
Carbon Fiber ◽  
Creep Strain ◽  
Strain Rates ◽  
Molding Compound ◽  
Sheet Molding Compound ◽  
Tension And Compression ◽  
Fiber Sheet ◽  
Stress States ◽  
Carbon Fiber Sheet

The creepage behavior of one thermosetting carbon fiber sheet molding compound (SMC) material was studied applying in-plane loading at 120 °C. Loads were applied in bending, tension and compression test setups at the same in-plane stress level of 47 MPa. Different creep strain rates were determined. The creep strain rate in flexural loading was significantly higher than in tensile loading. The test specimens in compression loading collapsed within minutes and no findings regarding the creep strain rates were possible. Overall, it was observed that the thermosetting press resin of this industrially used material had only little creep load bearing capacity at the mentioned temperature when loaded in mixed stress states. The test data has high usage for estimating design limits of structural loaded SMC components at elevated temperature.

An Analytical Solution for Evaluating Gasket Stress Change in Bolted Flange Connections Subjected to High Temperature Loading

2005 ◽  
Vol 127 (4) ◽  
pp. 414-422 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Akli Nechache
Keyword(s):  
Elevated Temperature ◽  
Operating Temperature ◽  
Interaction Model ◽  
Elastic Interaction ◽  
Bolted Joints ◽  
Analytical Models ◽  
Cover Plate ◽  
Thermally Induced ◽  
Internal Fluid ◽  
Bolted Flange

The tightness of bolted flanged joints subjected to elevated temperature is not properly addressed by flange design codes. The development of an analytical method based on the flexibility of the different joint components and their elastic interaction could serve as a powerful tool for elevated temperature flange designs. This paper addresses the effect of the internal fluid operating temperature on the variation of the bolt load and consequently on the gasket stress in bolted joints. The theoretical analysis used to predict the gasket load variation as a result of unequal radial and axial thermal expansion of the joint elements is outlined. It details the analytical basis of the elastic interaction model and the thermally induced deflections that are used to evaluate the load changes. Two flange joint type configurations are treated: a joint with identical pair of flanges and a joint with a cover plate. The analytical models are validated and verified by comparison to finite element results.

Simulation of Creep/Relaxation Behavior in Bolted Flange Joints Based on 3-D Viscoelasticity Model of Gasket

2009 ◽  
Author(s):  
Atsushi Yamaguchi ◽  
Hirokazu Tsuji ◽  
Takashi Honda
Keyword(s):  
Room Temperature ◽  
Fe Analysis ◽  
Fe Model ◽  
Flange Joint ◽  
Test Device ◽  
Reduction Behavior ◽  
Nanoindentation Testing ◽  
Internal Fluid ◽  
Fiber Sheet ◽  
Bolted Flange

It is well known that an axial bolt force which tightens a gasket decreases due to a creep of non-asbestos gaskets. A bolted flange joint contains a combined condition of the creep/relaxation. A reduction behavior of a tightening pressure due to an effect of creep/relaxation is related to lifetime assessment of the non-asbestos gasket, and a leakage prevention of internal fluid. In this research, the creep/relaxation of the bolted flange joint using the non-asbestos gasket is measured. The compressed creep test is carried out using four-inch flanges and non-asbestos compressed fiber sheet gaskets. The test conditions are room temperature and 90 hours. The result of creep/relaxation is evaluated by 3-D viscoelasticity model. The creep/relaxation that was evaluated by 3-D viscoelasticity model and the Young’s modulus of the non-asbestos gaskets that was measured by the nanoindentation testing is applied to the FE analysis. FE model that include viscoelasticity is 1/16 of the test device. The stress state of the non-asbestos gasket was confirmed by the FE analysis. Then, the validity of creep/relaxation of the non-asbestos gaskets that was evaluated by the 3-D viscoelasticity model was shown by comparison with the experimental value and the analysis result.

scholarly journals Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1473
Author(s):  
Jun Zhao ◽  
Kang Wang ◽  
Shuaibin Wang ◽  
Zike Wang ◽  
Zhaohui Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
High Volume ◽  
Sem Analysis ◽  
Geopolymer Concrete ◽  
Ordinary Concrete ◽  
Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

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