This paper aims to verify the reliability of the creep-life assessment regarding the STS304H-Type tube for which the hardness method of H. Tanaka is used. For this purpose, the creep-rupture test and the hardness test were conducted with a new tube and used tubes that were exposed to 96,000 hr under a 650oC condition. The hardness value of the used tubes is higher than that of the new tube by approximately 12 Hv to 15 Hv. This test result was applied to the creep-life assessment of the STS304H-Type for which the H. Tanaka hardness method was used, and the life consumption of the used tubes was evaluated as 13%. The rupture times of the new and used tubes are 802 hr and 707 hr, respectively. The use of the test results as a substitution of the results of the Larson Miller Parameter for a life-assessment tool produced a life-consumption calculation of approximately 12%. Similar results can be confirmed between the Larson Miller Parameter method and the hardness method.

Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. However, the Bauschinger effect reduces the compressive residual stresses as a result of prior tensile plastic strain, and decreases the beneficial autofrettage effect. The purpose of the present paper is to predict the accurate residual stress of SNCM8 high strength steel using the Kendall model which was adopted by ASME Code. The uniaxial Bauschinger effect test was performed to decide BEF, then this constant was used in calculation. There were some differences between theoretical solution and modified solution.

Elastomeric O-rings have been the most common seals due to their excellent sealing capacity, and availability in costs and sizes. One of the critical applications of O-ring seals is solid rocket motor joint seal where the operating hot gas must be sealed during the combustion. This has long been a design issue to avoid the system failure. For laterally constrained, squeezed and pressurized condition, deformed shape of O-ring was measured by computed tomography method and CCD laser sensor, compared with numerical calculations. As clearance gap changes, sealing performance had been evaluated on peak contact stresses at top, bottom and side contact surfaces. As clearance gap increases, peak contact stresses and contact widths in top and side contact surfaces increase, and the asymmetry of stress distributions is promoted due to pressure increase. It is suggested that peak stress of bottom contact surface can be approximated by simple superposition of peak ones due to squeeze and pressure. Under pressurized condition, sealing performance is dependent on not peak stresses of bottom and side contact surfaces but that of top.