REMAINING SERVICE LIFE DETERMINATION METHOD FOR CR-MO STEEL HEATING FURNACE PIPE

摘要

PROBLEM TO BE SOLVED: To predict the remaining service life of pipe with high accuracy in a short time by comparing the relative amount of carbide taken from a subject and the lattice constant thereof with the relative amount of carbide taken preliminarily from a material used for a long time and the lattice constant thereof, and observing the micro texture. SOLUTION: A ultrasonic wall thickness measurement is applied to a Cr-Mo steel heating furnace pipe being a subject. When the pipe is corroded after the surface thereof is ground and mirror finish polished, a replica of the micro texture in the pipe is formed. Carbide is extracted from the ground powder generated at the time of grinding the pipe, and then an analysis of X-ray diffraction is applied thereto. The ground powder is dissolved with phosphate, and the solution is filtered by a filter to collect the remainder, and then the content of the remainder and the lattice constant is measured while the identification of the remainder is made, and also the relative amount is measured. Thereafter, it is determined whether the subject is in a range of experience to which a remaining service life determination method can be applied, or not. Then, the ovservation of micro texture of replica and the comparison with data obtained formerly are carried out, and the relative amount of carbide and the lattice constant are compared with those taken preliminarily from the material used for a long time. Accordingly, degrading can be estimated.