METHOD FOR EXTENDING LIFE OF HIGH-TEMPERATURE PIPING AND LIFE-EXTENDING STRUCTURE FOR HIGH-TEMPERATURE PIPING.

摘要

If it is determined that steady continued use is not possible according to a remaining-life evaluation at a weld section of high-temperature piping based on creep ruptures, insulation material covering a site of the high-temperature piping at high risk of creep rupture is partially removed to locally lower the temperature of the outer surface of the high-temperature piping and extend the life of the site at high risk of creep rupture. In addition, the width of an exposed part where said insulation material was partially removed is at least twice the distance where the change in stress between the tensile stress and compressive stress generated on the high-temperature piping due to removing said insulation material from the stripped end of the exposed part changes from tensile stress to compressive stress and the compressive stress subsequently approaches zero. The distance where said compressive stress approaches zero after the tensile stress changes to compressive stress is calculated according to formula (1). βx=5 (1), where β is represented by formula (2). Here, v is the Poisson ratio, a is the average radius of the piping, and h is the thickness of the piping.