The effect of pipe bend radii on guided wave propagation in small diameter pipes

摘要

Guided waves are an exciting and relatively new non-destructive testing technique usedrnfor screening pipes for corrosion. The technique works well in straight lengths of pipernand can be used to provide information about corrosion severity. However, pipe bendsrnare known to distort the signal. This could result in false identification of flaws that arernnot actually there (so called ‘false positives’) or missing flaws that are present (‘falsernnegatives’). Additionally, newly developed flaw sizing techniques rely on accuraternamplitudes of reflected wave modes and would therefore become inaccurate if thernpropagation though a pipe bend altered these. Work has been carried out to quantify therneffects of pipe bends on guided wave propagation using finite element analysisrnprocedures. Based on an understanding of how the bends affect the signals, methods forrndistortion removal are discussed.