The loose flange connection consists of the loose flange and the stub end made of stainless steel, shows the high chemical resistance by low cost. The spiral wound gasket is used widely because of that's versatility. However, the spiral wound gasket is not used very much for the loose flange connection, because it is required high tightening force, and that's performance is not clear.
In this paper, the sealing performance of the bolted loose flange connection with spiral wound gasket is evaluated by experiments and FE analysis. The connection size is JIS 10K50A, the test gasket is spiral wound gasket with flexible graphite filler because it is used most widely. In experiments, the axial bolt forces are controlled by using the bolts that is attached with strain gage and the stress of the stub end curve face is measured by using strain gages. The test gas is helium and the leak rate is measured by pressure drop method. In FE analysis, the stub end stress and the contact gasket stress distributions are measured. The leak rates are estimated using contact gasket stress distribution and the relationship between leak rate and contact gasket stress, and compared with experimental results. In addition, the effects of the flange rotation and misalignment are evaluated.

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Control process of fracture initiation in structural steels is studied based on the past microfractgraphical observation. It is shown that the fracture initiation process in Ferrite-Pearlite steels is controlled by propagation of crack from brittle particles to ferrite matrix. It is also suggested that the fracture initiation in Bainite-Martensite steels is restricted by high stress necessary for crack to pass through the “effective grain” boundary, which explains the good toughness in spite of high strength in these steels.

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The occurrence of Zinc-induced cracking (ZIC) is influenced by the compressive plastic strain emerged at earlier time of hot-dip galvanizing process. But the role of strain has not been clarified. It is the purpose of present paper to discuss the effect of the strain on ZIC.
Weld heat-affected zone (HAZ) shows the brittle behavior in tensile test at galvanizing temperature, 450°C, showing grain boundary fracture. Micro crack is easily initiated under this condition with compressive plastic strain. The micro crack also grows up to be a small size crack under the compressive strain. The small size crack becomes macro size ZIC by the tensile stress converted from compressive stress at later time of hot-dip galvanizing. At the same time, surface energy decreases due to diffused Zn along grain boundary causing low fracture strength.

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On March 12, 2014, a natural gas explosion occurred at a five-story building in New York City. The building was situated on the west side of Park Avenue between East 116th Street and East 117th Street in the East Harlem district of Borough of Manhattan. Eight people died, 61 people were injured, and more than 100 families were displaced from their homes as a result of this accident. National Transportation Safety Board (NTSB) released the final report on the cause of this accident on June 9, 2015. The root cause was a gas leak from a defect in plastic fusion welding of gas main and service tee joint. This paper describes the accident according to the NTSB report.

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