The reactors and re-generators in RFCC and FCC units in refineries are provided with concrete refractory linings. The influence of these linings on the flexibility of the nozzle-shell intersections and the local stress distributions around those intersections is not considered in present designs. In this paper, three-dimensional, nonlinear finite element analyses were performed to evaluate the influence of refractory lining rigidity on the flexibility of nozzle-head intersections. The results of these analyses can be applied to the thermal stress analysis of piping to obtain reaction forces and moments on nozzles. The application of flexibility factors results in a reduction of the reaction forces and moments. The influence of refractory lining rigidity on the local stress distributions around the intersections was also studied. Shell elements were applied to the nozzle, head and cylindrical shell, and solid elements were applied to the refractory lining. A boundary element was applied to express the contact boundary, which transfers only a compressive force. As a conclusion, a new analysis method for nozzle-head intersections with refractory linings is proposed.

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Silicon nitride ceramics are superior in strength at high temperature, and apply to ceramic gas-turbines and fuel cells. However ceramics are brittle and sensitive to flaws. To overcome the sensitivity and improve the reliability of ceramics, we developed Si₃N₄-SiC composites which show excellent crack-healing ability.
The oxidation behavior of Si₃N₄-SiC composites having crack-healing ability was investigated and compared with heat-treatment conditions. The oxidation test was carried out at 1000°C for 500hr. The measurement of weight gain, bending strength, observation of oxidized surfaces were carried out.
The main results obtained are as follows: (1)The weight gain of Si₃N₄-SiC composites treated crack-healing was lower. (2)The bending strength of Si₃N₄-SiC composites increased the value after oxidation. (3)The crack healing conditions are useful for increasing the oxidation-resistance, and improving strength.

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This report shows results of fatigue properties and fracture mechanism of dual phase stainless steels. The dual phase stainless steels are often used because of advantageous properties of corrosion resistance for seawater, weldability and workability. Recently, a new fatigue problem becomes important, because number of cycles to failure that should be taken into consideration for maintenance increases over 10⁷. For the ultra-high-cycle fatigue, interior inclusions in materials are dominant factor in fatigue life, but the fracture mechanism is not made clear completely.
Results of the ultra-high-cycle fatigue properties are shown. The interior fracture takes place at ultra-high-cycle region. The crack growth life is predicted by using fracture mechanics.

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A method for enhancement of the magnetic signal by using the magnetically supporting plate was proposed to solve the disadvantage of the lower signal-to-noise ratio of the output signal in the magnetic flux leakage technique. In this study, the magnetic characteristic and the effect of improvement of a magnetic signal with the magnetically supporting plate were clarified by using three-dimensional finite element analysis for the far-side magnetic flux leakage method, and the influence of the magnetically supporting plate parameters was examined. Moreover, the experimental work was done to confirm the calculated results. As a result, some accurate specifications were given on the selection of the magnetically supporting plate parameters in its practical usage.

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We discuss the use of differential absorption images in a system for gas leak detection. The system can visualize leakage spots of LP-gas (main ingredient is propane-gas) in real time using two OPO (optical parametric oscillator) -lasers, an infrared camera (IR-camera) , an optical system and a reflecting screen. We applied optical fiber to an earlier developed system to increase safety and convenience. In consequence, this new optical fiber system demonstrated remarkably high capabilities for real time observation of a gas leak on images, compared with an earlier developed system. With software that processes differential absorption images, the system acts as a monitor of leakage spots of LP-gas. In LP-gas facilities, this new system will be more safely and conveniently handled than existing systems.

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