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

ABSTRACT 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

Proceedings of PVP2005 2005 ASME Pressure Vessels and Piping Division Conference Experimental Investigation and Finite Element Analysis of the Free Vibration Problem of Bolted Joint

ABSTRACT Evaluation of the natural frequency and the natural mode of vibration of bolted joints is particularly important to avoid the failure of the structure due to resonance. In this paper, natural frequencies of the bending vibration of a bolted joint with simple configuration are measured with strain gages mounted on the surface of test specimen, and the effects of surface roughness, axial bolt force and bolt position are systematically investigated. Then, a numerical approach is proposed to analyze the free vibration problem of bolted joint, where selective reduced integration (SRI) scheme is introduced into the finite element formulation to improve the computation efficiency in solving the concerned eigen value problems. The effectiveness of the numerical procedure proposed here is validated by experimental measurements of the natural frequencies of the first mode