EXTERNAL CORROSION DETECTOR FOR BURIED METAL PIPELINE

摘要

PURPOSE:To enable detection (estimation) of an external corrosion of a metal pipeline simply by a method wherein a box body having a closed hollow part is buried at a position near the outer surface of a buried metal pipeline to introduce a pressure fluid into the hollow part of the box body and then, a change in pressure is monitored. CONSTITUTION:A box body 2 has closed hollow parts 3a-3c with wall thicknesses thereof of T1-T3 and formed to meet a requirement of TsT3T2T1 when a pipe thickness of a metal pipeline 1 is represented by Ts. A through hole 6 pierces each of the hollow parts, then, a pressure fluid introduction tube 7 is connected thereto as sealed while being opened at a manhole 8 at the other end of the tube 7. Then, a pressure fluid is introduced from the tube 7 leading to the hollow part 3a within the manhole 8 to apply a specified pressure to the hollow part 3a and a change in the pressure is checked with a manometer. When the pressure lowers, it is learned that a tiny hole is caused in the wall of the hollow part 3a. The same test is conducted for the hollow part 3b and then, that 3c. Thus, it is possible to presume that a corrosion of the same degree as that on the wall surface of the hollow part 3c occurs on the outer surface of the metal pipeline 1 with a confirmation that the pressure at the hollow part 3c can not be maintained.