This paper deals with the effects of the nominal diameter of a pipe flange connection with a non-asbestos spiral wound gasket under an internal pressure on the mechanical characteristics such as the contact gasket stress distribution which governs the sealing performance, the load factor and the hub stress of the connection. The stresses in the pipe flange connections with the nominal diameters from 3”to 24” under internal pressure are analyzed using finite element method taking account the hysteresis and non-linearity in the non-asbestos spiral wound gasket. As a result, it is found that the variations in the contact gasket stress distributions are substantial due to the flange rotation in the pipe flange connections with the larger nominal diameter. Leakage tests were conducted to measure the axial bolt forces (the load factor) and the hub stress. The results obtained from the FEM analyses are fairly consistent with the experimental results concerning the variation in the axial bolt forces (the load factor) and the hub stress. Using the obtained contact gasket stress distributions and the fundamental relationship between the amount of leakage and the gasket stress, the amount of the leakage of the pipe flange connection is estimated. The estimated results are in a fairly good agreement with the measured results. The difference in the hub stress between the FEM and ASME code is demonstrated and the sealing performance of the non-asbestos gasket is discussed.

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Quenched and tempered JIS SCM435 (SCM435⁄QT) was subjected to strain-controlled low cycle fatigue test after hydrogen charging. The results were compared with those of normalized carbon steels S10C and S45C, whose microstructures are composed of ferrite and pearlite in contrast to the martensitic microstructure of SCM435⁄QT. Thermal desorption analysis was also conducted. The features of hydrogen effect on cyclic deformation and fracture are examined. Further, the influences of material factors and possible improvements have been discussed. The desorption spectra of SCM435⁄QT are unexpectedly similar to those of normalized carbon steels, having main peak at around335K and sub peak at around 365K. It is estimated that they are concerned with dislocation in ferrite matrix and with the prior austenite high angle boundary. The hydrogen charging acts to raise the monotonic flow stress by 50MPa with less than 0. 5 mass-ppm hydrogen, denying the enhanced plasticity that is often ascribed to hydrogen embrittlement. This hardening is carried on into the cyclic stress amplitude; the stress amplitude is increased as the case of normalized carbon steels. This increased stress amplitude may manifest the dynamic strain aging from the interaction between dislocation and hydrogen-vacancy pair, which has been proposed on S10C previously. Besides the small amount of hydrogen enhances the fracture of SCM435⁄QT largely and its fracture appearance resembles closely to those of normalized S10C steel reported before. The crack initiates at inner side and propagates in a fish-eye manner with quasi-cleavage or grain boundary facet; grain boundary facet becoming dominant with increased amount of hydrogen. Those facts assure that martensitic steel is not inevitably sensitive to hydrogen embrittlement; it may be improved to industrially acceptable level from the following material factors, such as type and size of inclusions, grain boundary segregation and precipitation.

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At start-up operation of hot dip galvanizing baths to galvanize steel products, several leakage accidents of liquid zinc due to the damage in the vicinity of welded parts between side and bottom plates have been reported. Generally, liquid zinc is transferred to a new bath which has been heated adequately. In some of the accidents, however, it was found that transferred liquid zinc solidified in the bath heated inadequately. In order to determine a cause of the damage, this paper investigates the stresses of the bath which are caused by thermal expansion of solidified zinc heated continuously. At first, thermal distributions of the furnace and the bath are investigated by unsteady heat conduction analysis. Next, stresses of the vicinity of welded parts between bottom and side plates of the bath, are obtained by static analysis using the thermal distribution.

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On September 9, 2010, a natural gas transmission pipeline ruptured in a residential area in San Bruno, California. The pipeline released large amount of natural gas. The released gas ignited, resulting in a fire that destroyed many residential houses, killed eight people and injured dozens of people. The National Transportation Safety Board issued the report on the cause of this accident. This paper describes the accident.

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Many aluminum dome roofs have been installed on external floating roof tanks in USA and Europe in recent 20 years. After the Clean Air Act Amendments were promulgated by US Federal Government in 1990, the evaporative emission from the external floating roof due to both wind and solar heat was regulated to be reduced. The aluminum dome roof is the most effective solution for reducing these emissions. This paper explains the situation, the history, the structure and the design criteria of the aluminum dome.

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