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(2001). Effects of impurity elements on solidification cracking in electron beam welding of pipeline steel. Study of all‐position electron beam welding of large diameter pipeline joints (3rd report) Welding International: Vol. 15, No. 5, pp. 354-359.

Conventionally, the site welding of large diameter natural gas line pipes have been performed by using arc welding processes, including shielded metal arc welding and. gas metal arc welding. In order to achieve a drastic improvement of the productivity, authors have executed fundamental study on the application of the electron beam welding process to the site welding of line pipes.This paper, as the first report, describes the influence of the welding position to the proper electron beam welding parameters in API-5L X65 line pipe steel of 19 mm thick. As a result of welding trials in various welding positions, it was clarified that the beam focusing condition and the welding speed should be properly controlled according to the welding position to obtain satisfactory weld bead shape. In the flat position, to prevent the under-fill on the surface, the beam focus had to be located under the plate surface. On the contrary, in the over-head position, the proper weld bead was obtained by positioning the beam focus outside the plate surface. In the vertical upward position, welding speed had to be kept lower to prevent the humping bead formation.On the basis of above investigation, it has been basically confirmed that the all-position circumferential welding of large diameter line pipes can be performed with the electron beam welding process.

Summary This paper presents the results of laboratory investigations conducted to better our definition of the serviceability of bimetallic pipe manufactured by the thermohydraulic (tight-fit) method for Mobile Bay service. Both Alloy 625/API X-65 and Alloy 825/API X-65 tight-fit pipe (TFP) were evaluated under conditions of (1) standard corrosion test environments to evaluate the metallurgical conditions of the corrosion-resistant-alloy (CRA) liner tubes, (2) long-term, full-scale TFP exposure under a simulated Mobile Bay production environment containing high levels of H2S and CO2, and (3) hydrogen-permeation experiments designed to examine potential effects of CRA liner collapse from hydrogen produced by corrosion on the ID and/or cathodic protection on the OD. Results indicate that bimetallic TFP exhibited an acceptable metallurgical condition of the CRA liner materials. Under the simulated Mobile Bay production environment, TFP exhibited good resistance to general corrosion, stress-corrosion cracking (SCC), and liner collapse. Hydrogen-permeation tests indicate that very conservative estimates of service-life liner collapse from interfacial hydrogen pressure range from 150 to more than 800 years, depending on conditions. For all practical purposes, liner collapse from hydrogen is not a limiting factor for TFP flowline applications.

Cladosporium cladosporioides No.9の無細胞抽出液より硫安沈殿,ブチルートヨパール, DEAE-トヨパールおよびトヨパールHW55のクロマトグラフィーにより酢酸エステルを特異的に分解する酢酸エステル分解酵素(Est I, Est II)を単離精製した. 各精製酵素の分子量はゲルクロマトグラフィーによりEst Iは約6.3万, Est II は約6.6万と推定された. また,各酢酸エステル分解酵素の至適反応温度はEst Iは35°C, Est IIは30°Cであった.熱安定性はともに50°C, 30分処理で完全に失活した.至適pHはEst IはpH 9.1, Est IIはpH 9.3であった. pH安定範囲は,前者がpH 7～9,後者がpH 5～6であった.両酵素ともにDFP, PMSFに阻害され,エゼリンで阻害されないことによりセリン残基を有するカルボキシエステラーゼと推定された.SH基阻害剤であるPCMB, DTNBおよび金属イオンキレート剤であるEDTAでは阻害されなかった.また, Ag2+および2価の重金属イオンのCu2+, Hg2+で強く反応を阻害された. エチルエステルに対する基質特異性は,酢酸エステルに比較して最大でも約10～20%の相対活性しかなかった.トリグリセリド,モノグリセリドの長鎖脂肪酸を持つものにはまったく作用せず,短鎖脂肪酸を持つものにわずかに活性を示した.酢酸エステルに対してはEst Iは酢酸イソアミルに対してEst IIは酢酸イソブチルに対して最大の活性を示し,酢酸β-フェネチルに対しても高い分解活性を示した.本酵素はアルコールの酢酸エステルを特異的に分解するカルボキシエステラーゼであった.