圧力技術
Online ISSN : 1347-9598
Print ISSN : 0387-0154
ISSN-L : 0387-0154
50 巻, 6 号
選択された号の論文の5件中1~5を表示しています
論文
  • 大矢 弘史
    原稿種別: 論文
    2012 年 50 巻 6 号 p. 306-314
    発行日: 2012/11/25
    公開日: 2012/12/27
    ジャーナル フリー
    The finite element method is applied to buckling analysis of cylindrical shells partially subjected to external and internal liquid pressures. The axisymmetric shell element is used with displacement field within each element is represented by Fourier circumferential components. The shells are assumed to stand vertically with the lower end clamped and the upper end clamped, simply supported or free. The analyses are performed for a wide range of the geometric parameter Z and the buckling liquid heights are obtained. The effects of the internal liquid height and the difference of mass density between external and internal liquids on the buckling liquid height are investigated. Based on the results of the finite element analyses, the simplified equations to calculate buckling liquid height with the effect of internal liquid are established.
  • 高木 愛夫, 大宮 祐也, 小林 隆志, 沢 俊行
    原稿種別: 論文
    2012 年 50 巻 6 号 p. 315-325
    発行日: 2012/11/25
    公開日: 2012/12/27
    ジャーナル フリー
    The effects of scatter in bolt preloads and the nominal diameter (3inch and 20inch) of pipe flange connections with gaskets subjected to internal pressure are examined. The scatter in the bolt preloads tightened by a torque wrench was measured for smaller and larger pipe flange connections (3inch and 20inch) . The contact gasket stress distributions of the pipe flange connections are calculated with the measured bolt preloads using elasto-plastic finite element method (FEM) taking into account the hysteresis and the non-linearity of the stress-strain curves of the gaskets. The effects of the scatter in the bolt preload on the sealing performance are also examined for the pipe flange connections. The bolts were tightened using torque wrenches according to JIS B 2251 and ASME PCC-1 procedure. By using the calculated contact gasket stress distributions in the pipe flange connections under the internal pressure and the measured results from the leakage tests, the sealing performance is evaluated. The effect of the scatter in the bolt preload is found to be substantial on the sealing performance. The difference in the leakage is found to be small between JIS and ASME tightening procedures. The assembly efficiency η based on the amount of leakage is newly proposed as η =0. 65 for bigger nominal diameter pipe flange connection while η =0. 8 for smaller nominal diameter pipe flange connection.
  • 近藤 康治, 宮下 藍, 沢 俊行, 大宮 祐也, 小林 隆志
    原稿種別: 論文
    2012 年 50 巻 6 号 p. 326-333
    発行日: 2012/11/25
    公開日: 2012/12/27
    ジャーナル フリー
    Pipe flange connections have been used in chemical plants, petro-chemical industry and so on. They are tightened with a lot of bolts and nuts by torque wrench, impact wrench and so on. When the impact wrench is used for tightening a lot of bolts and nuts in pipe flange connection with gaskets, it is well known that a large scatter is assumed to occur in tightening the lots of bolts in the connection using the impact wrench. In the present paper, the scatter in bolt preloads in a pipe flange connection with 20”nominal diameter using air impact wrenches and air torque wrench (JGUN) was measured. Firstly, the best operation time for the air impact wrench was examined and it was determined as 3 seconds. The tightening coefficient was calculated taking into account the interference of the adjacent bolt loads and it was obtained as αA=1. 38∼1. 48 while the conventional value was around αA=2. 5∼4. 0. In addition, it was found that all axial bolt forces tightened by the air impact wrench were larger than the target bolt force. Then, the tightening was carried out using an air torque wrench. The tightening coefficient by the air torque wrench was obtained as =1. 321. 41 while all axial bolt forces were smaller than the target bolt force. The leakage tests were carried out for the connection tightened by air impact wrench and air torque wrench. The tightness parameter of the connection tightened by the air impact wrench was obtained as 8081070 while it was as 661 for the connection tightened by the air torque wrench. As the result, the impact wrenches such as the air impact wrench and the air torque wrench were applicable to the actual bolt tightening because the tightening coefficient was smaller than the conventional value.
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