TY - GEN
T1 - Scatter of bolt preloads in pipe flange connection tightened by impact wrench and the effect on sealing performance
AU - Kondo, Koji
AU - Omiya, Yuya
AU - Kobayashi, Takashi
AU - Sawa, Toshiyuki
PY - 2011/1/1
Y1 - 2011/1/1
N2 - 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 impact wrenches was measured. The ratio of the maximum and the minimum bolt force is called the tightening coefficient. The tightening coefficient is calculated taking into account the interference of the adjacent bolts. The value of the coefficient is compared with the measured results obtained from torque wrench tightening. Then, FEM calculation for analyzing the gasket stress distribution in the process of bolt tightening is carried out. Using the obtained gasket stress distribution and the data obtained from the fundamental gasket characteristics, an amount of leakage is estimated. In addition, the bubble leak testing was carried out. The estimated result is in a fairly good agreement with the measured result. Discussion is made on the tightening coefficient by impact wrenches and the effect of the scatter in bolt preloads on the sealing performance.
AB - 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 impact wrenches was measured. The ratio of the maximum and the minimum bolt force is called the tightening coefficient. The tightening coefficient is calculated taking into account the interference of the adjacent bolts. The value of the coefficient is compared with the measured results obtained from torque wrench tightening. Then, FEM calculation for analyzing the gasket stress distribution in the process of bolt tightening is carried out. Using the obtained gasket stress distribution and the data obtained from the fundamental gasket characteristics, an amount of leakage is estimated. In addition, the bubble leak testing was carried out. The estimated result is in a fairly good agreement with the measured result. Discussion is made on the tightening coefficient by impact wrenches and the effect of the scatter in bolt preloads on the sealing performance.
UR - http://www.scopus.com/inward/record.url?scp=84869187328&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84869187328&partnerID=8YFLogxK
U2 - 10.1115/imece2011-64613
DO - 10.1115/imece2011-64613
M3 - Conference contribution
AN - SCOPUS:84869187328
SN - 9780791854891
T3 - ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011
SP - 481
EP - 489
BT - Design and Manufacturing
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011
Y2 - 11 November 2011 through 17 November 2011
ER -