Influence of elevated temperature on axially loaded expansive cement grout borehole plug sealing performance

Bolted flange connections with gaskets have been used under high temperature and long-term conditions. Sometimes leakage accidents occur from the gasket interfaces due to the creep and relaxation phenomena. In the present paper, the changes of the gasket stress in bolted flange connections under high temperature conditions for a long-term are analyzed using FEM calculations taking into account the gasket temperature dependency. The gaskets used are PTFE-blended (V#GF300). It’s shown that the effect of the temperature on the stress-strain relationship of the gasket is substantial. The changes in the gasket stress of the connections for 12 months are analyzed using the FEM. The effects of nominal diameter of flanges, retightening and the fluid temperature (20 to 300 °C) on the change of gasket stress in the connections under elevated temperature are examined using the FEM calculations. It is found that the reduction in the gasket stress is over 40%. In addition, experiments to measure the axial bolt force were carried out. The calculated results are in a fairly good agreement with the experimental results. The results reveal that the long-term behavior of the bolted flange connections can be estimated in our study. Discussion is made on the effects of the bolt preload and retightening on the reduction of the gasket stress and the sealing performance.

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An Estimation of Long-Term Sealing Performance for Bolted Pipe Flange Connections With Spiral Wound Gaskets Under Elevated Temperature

Volume 2: Computer Technology and Bolted Joints ◽

10.1115/pvp2020-21138 ◽

2020 ◽

Author(s):

Koji Sato ◽

Toshiyuki Sawa

Keyword(s):

Elevated Temperature ◽

Heat Conduction Problem ◽

Estimation Method ◽

Transient State ◽

Sealing Performance ◽

Nominal Size ◽

Calculation Results ◽

Flexible Graphite ◽

Spiral Wound

Abstract SWGs (Spiral Wound Gaskets) are well known as a most used gasket type in bolted pipe flange connections all over the world. Recently, the connections with SWGs have been used under more severe conditions such as higher temperature and pressure, and in addition, the connections have been used in the more long-term application. Thus, it is necessary for plant owners (gasket users) to know the long-term characteristics of the connections with SWGs from a standpoint of integrity in the connections. In this study, the objective is to establish a long-term estimation method of sealing performance for bolted pipe flange connections with SWGs under elevated temperature. The long-term characteristics of pipe flange connections with SWGs are estimated using FEM calculations in which the fundamental mechanical characteristics of SWGs such as compression property under changed temperature is considered, thermal expansion behavior, creep relaxation and sealing performance are taken into considerations. For verification of FEM calculations, the experiments are carried out for the pipe flange connections with SWGs of which the nominal size is ASME class 300 2inch under elevated temperature and internal pressure. The gasket used is chosen as SWG with flexible graphite filler. The change in axial bolt forces and an amount of leakage are measured and the measured results are fairly coincided with the FEM calculation results. In addition, the contact gasket stress in the connection with SWG is shown in 72 months. The FEM calculations are performed as heat conduction problem in transient state.

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Effect of elevated temperature on strength and ductility of axially loaded hybrid fiber reinforced concrete columns

Structures ◽

10.1016/j.istruc.2021.09.099 ◽

2021 ◽

Vol 34 ◽

pp. 3548-3556

Author(s):

Arathi Krishna ◽

Saravana Raja Mohan Kaliyaperumal

Keyword(s):

Reinforced Concrete ◽

Elevated Temperature ◽

Concrete Columns ◽

Fiber Reinforced Concrete ◽

Fiber Reinforced ◽

Hybrid Fiber ◽

Reinforced Concrete Columns ◽

Axially Loaded ◽

Strength And Ductility

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Inelastic Analysis of Sealing Characteristics of Flanges With Metal Ring Joint Gasket at Elevated Temperature

Volume 2: Computer Technology ◽

10.1115/pvp2006-icpvt-11-93288 ◽

2006 ◽

Cited By ~ 2

Author(s):

Takuya Sato ◽

Kenichiro Kado

Keyword(s):

Elevated Temperature ◽

Plastic Strain ◽

Temperature Change ◽

Contact Pressure ◽

Dissimilar Material ◽

Metal Ring ◽

Load Path ◽

Material Combination ◽

Sealing Performance ◽

Operation Cycle

In a previous paper(1) presented in 2005 ASME PVP Conference, the authors investigated the elastic plastic behavior of dissimilar material flanges with a metal ring joint gasket operated at elevated temperature using FEA. Case studies were performed to study the effects of load path, material combination and flange size on the contact pressure and the plastic strain distribution in the ring joint gasket. In that paper, the authors concluded that the load path has a large impact on both, the contact pressure and the plastic strain, and, on the other hand, the material combination of the flanges and their size have small effects. In this paper, the authors present further FEA-based investigation on this mechanism. The first issue is the effects of meteorological changes, such as wind velocity, ambient temperature and rain, as is often the case with real energy and process plants. These meteorological changes result in the temperature change of bolts and flanges. The bolt temperature change causes different thermal expansion in the ring joint gasket and the bolts. This may affect the sealing performance. In this paper, the wind velocities were changed to investigate meteorological changes as a typical such change. The second issue is the behavior of the metal ring joint gasket after the second operation cycle. The metal ring joint gaskets are usually replaced after the first operation cycle, i.e., from start up to shut down. However, it is said that all ring joint gaskets are not replaced. In the previous paper, the behavior of the ring joint gasket during the first operation cycle was investigated. Increase of plastic strain in the sequential operation cycles is an important issue in terms of sealing performance. Therefore the behavior of the ring joint gasket in the second operation cycle was investigated. Finally the sealing mechanism and characteristics of this dissimilar material flanges under elevated temperature operation cycles were made clear.

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