PURPOSE: To make it possible to simply detect and monitor a fatigue damage degree, by adhering a plurality of strain gauges and measuring the distortion quantity of a piping elbow in the peripheral direction at the arbitrary point of time by at least one strain gauge with the advance of the fatigue of the piping elbow.
CONSTITUTION: A plurality of strain gauges 4W8 are adhered to a piping elbow 1 so as to be arranged to an area on the neutral axis of the piping elbow 1 or in the vicinity thereof and reaching the central part of said elbow 1 at least from the boundary parts of a curved pipe part and straight pipe parts and the distortion quantity of said area in the the peripheral direction is measured at the arbitrary point of time by at least one gauge among the strain gauges 4W8 with the advance of the fatigue of the piping elbow 1 and, from said distortion quantity, the number of repeated times of load before the breakage of the other arbitrary region to be detected by repeated load is calculated from formula. By this method, the fatigue damage degree of the elbow of a piping system covered with a heat insulating material and used at high temp. can be simply detected and monitored.
ISHIZUKI TOSHIO
NISHIOKA AKIO
SUMIKAWA MASAHARU
