Experimental Verification of Steel Pipe Collapse under Vacuum Pressure Conditions

28th IAHR symposium on Hydraulic Machinery and Systems

Autrique, R.^1 ; Rodal, E.^2

Policonductos, Cracovia 54, México City, Mexico^1

Instituto de Ingeniería, UNAM, México City, Mexico^2

关键词: Diameter-to-thickness ratios;    Experimental verification;    External pressures;    Hydraulic transients;    Hydroelectric systems;    Length to diameter ratio;    Pumping systems;    Thin-walled steels;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/49/5/052008/pdf
DOI  :  10.1088/1755-1315/49/5/052008

来源: IOP

【 摘 要 】

Steel pipes are used widely in hydroelectric systems and in pumping systems. Both systems are subject to hydraulic transient effects caused by changes in boundary conditions, such as sudden valve closures, pump failures, or accidents. Water column separation, and its associated vaporization pressure inside the pipe, can cause the collapse of thin walled steel pipes subject to atmospheric pressure, as happened during the well known Oigawa Power Plant accident in Japan, in 1950. The conditions under which thin walled pipes subject to external pressure can collapse have been studied mathematically since the second half of the XIX century, with classical authors Southwell and Von Mises obtaining definitive equations for long and short pipes in the second decade of the XX century, in which the fundamental variables are the diameter to thickness ratio D/t and the length to diameter ratio L/D. In this paper, the predicted critical D/t ratio for steel pipe collapse is verified experimentally, in a physical model able to reproduce hydraulic transients, generating vacuum pressures through rapid upstream valve closures.