GAS PIPELINE WALL THICKNESS AND FLAW DETECTION

摘要

A new ultrasonic method for measuring wall thickness and detecting material flaws in natural-gas pipelines (30), risers, and similar structures. The method is inherently suitable for the task, because it relies on the use of the natural gas (G) as the coupling fluid for transmitting the probing ultrasonic signals into and out of the pipe wall. Furthermore, the method facilitates the operation of the inspecting from the inside of the pipe (30). An experimental apparatus is also described. Significantly, it is shown that by the use of a diplexer (18), the same transducer (15) can be used to generate and detect the probing ultrasonic signals. The same configuration is used in commercial ultrasonic inspecting of oil pipelines where oil is the coupling fluid; but until now this method could not be used in natural gas pipelines due to the low specific acoustic impedance of natural gas.