551 Development of Test Equipment for Measuring Compression Characteristics of Sheet Gasket at Elevated Temperature

2007 ◽  
Vol 2007 (0) ◽  
pp. 140-141
Author(s):  
Toshimichi FUKUOKA ◽  
Masataka NOMURA ◽  
Minoru ASAHINA ◽  
Takashi NISHIKAWA
Keyword(s):  
Elevated Temperature ◽  
Test Equipment ◽  
Compression Characteristics

Development of Test Equipment for Measuring Compression Characteristics of Sheet Gaskets at Elevated Temperature

2007 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Masataka Nomura ◽  
Yoshihiko Hata ◽  
Takashi Nishikawa
Keyword(s):  
Elevated Temperature ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Great Difficulty ◽  
Test Equipment ◽  
Experimental Point ◽  
Stress Strain ◽  
Sealing Performance ◽  
Compression Characteristics

Evaluation of the sealing performance of pipe flange connection is significantly important for the safety of pipe line structures. The compression characteristics of sheet gaskets primarily affect the mechanical behavior of flanged connections. It is known that the stiffness of sheet gaskets decreases with an increase in temperature. Therefore, the compression test must be conducted at various levels of elevated temperatures. From the experimental point of view, however, a great difficulty is involved in measuring the compression characteristics of gaskets at elevated temperature. For this reason, a definite testing procedure has not yet been established. In this paper, a prototype of compression test equipment has been developed for measuring the stress-strain curves of sheet gaskets at elevated temperature. The test equipment is compact and the experiments can be conducted with a fairly easy operation. It can control the gasket stress from zero to 30MPa while keeping the temperature of test specimen at different levels from room temperature to 300° C and higher. Aramid sheet gaskets are selected as test specimens. Experimental results show that the gasket stiffness drops with an increase in temperature. The shapes of the compression curves at different temperatures are similar, and those curves move in the direction of lower stiffness as the temperature is increased. It is concluded that the test equipment proposed here has a high promise to measure the stress-strain curves of sheet gaskets and estimate the sealing performance of pipe flange connections at elevated temperature.

Analysis of Thermal and Mechanical Behavior of Pipe Flange Connections by Taking Account of Gasket Compression Characteristics at Elevated Temperature

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Masataka Nomura ◽  
Takashi Nishikawa
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Reduction Rate ◽  
Service Condition ◽  
Numerical Results ◽  
Design Stage ◽  
Bolt Preload ◽  
Element Approach ◽  
Preload Reduction ◽  
Compression Characteristics

Sealing of contained fluids is the primary performance required for pipe flange connections. It is well known that the leakage is likely to occur when contained fluids at high temperature are concerned. Due to the differential thermal expansion of each part, bolt preloads that tighten a pair of pipe flanges tend to decrease. Therefore, it is significantly important for the joint safety to estimate the amount of bolt preload reduction at the design stage. In this paper, a finite element approach is proposed to analyze thermal and mechanical behavior of pipe flange connections at elevated temperature, by incorporating the stress–strain curves of sheet gaskets measured in the temperature range which covers its usual service condition. Then, the reduction rate of bolt preloads at elevated temperature is systematically evaluated. The analytical objects are pipe flange connections tightened with aramid sheet gaskets. When a pipe flange connection is subjected to thermal load, the gasket stress usually decreases along unloading curves. The temperature dependency of gasket stiffness is considered by defining Young’s modulus in unloading E*, which can be introduced into FE formulation using ordinary solid elements. Numerical results show that bolt preloads are decreased by as much as 30% of the initial value when using aramid sheet gaskets of 3 mm thickness. The effectiveness of the proposed numerical method has been confirmed by comparing the numerical results of bolt preload reduction to experimental ones.

Analysis of the Mechanical Behavior of Pipe Flange Connections by Taking Account of Gasket Compression Characteristics at Elevated Temperature

2009 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Masataka Nomura ◽  
Takashi Nishikawa
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Reduction Rate ◽  
Numerical Results ◽  
Design Stage ◽  
Initial Value ◽  
Bolt Preload ◽  
Element Approach ◽  
Preload Reduction ◽  
Compression Characteristics

Sealing of contained fluids is the primary performance required for pipe flange connections. It is well known that the leakage is likely to occur when contained fluids at high temperature are concerned. Due to the differential thermal expansion of each part, bolt preloads that tighten a pair of pipe flanges tend to decrease. Therefore, it is significantly important for the joint safety to estimate the amount of bolt preload reduction at the design stage. In this paper, a finite element approach is proposed to analyze thermal and mechanical behavior of pipe flange connections at elevated temperature, by incorporating the stress-strain curves of sheet gaskets measured in the previous paper. Then, the reduction rate of bolt preloads at elevated temperature is systematically evaluated. The analytical objects are pipe flange connections tightened with aramid sheet gaskets. When a pipe flange connection is subjected to thermal load, the gasket stress usually decreases along unloading curves. The temperature dependency of gasket stiffness is considered by defining Young’s modulus in unloading E*, which can be introduced into FE formulation using ordinary solid elements. Numerical results show that bolt preloads are decreased by as much as 30% of the initial value when using aramid sheet gaskets of 3mm thickness. The effectiveness of the proposed numerical method has been confirmed by comparing the numerical results of bolt preload reduction to experimental ones.

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Sign in / Sign up

Export Citation Format

Share Document