導波超音波檢測技術應用於管線腐蝕檢測

Using the Guided Wave Ultrasonic Technique for Corrosion Inspection on Pipelines

工業革命後，在基礎工業建設中分布各式各樣的運輸管線，在公共安全的考量下這些管線之安全乃極為重要。導波超音波技術可提供快速且長距離之管線腐蝕檢測，尤以扭矩模態導波T（0,1）更是被廣泛地應用於檢測被隱藏之管線區段，由於超聲導波技術可評估不易接近之管線，使得此技術在管線非破壞檢測技術應用上獲得肯定。本研究乃針對導波檢測管線上腐蝕的效能進行分析，分別探討局部腐蝕、均勻腐蝕、銲道腐蝕、銲道裂縫與銲接支撐架腐蝕等案例，針對腐蝕檢測時T模態之反射回波訊號可檢出腐蝕之位置與計算截面積改變量，F模態之反射回波則可定義出腐蝕之周向分布長度範圍。針對管線特徵區的腐蝕，本研究結果顯示異常突起之F模態反射回波訊號可定性分析出管線特徵區腐蝕的存在。

Safety of pipelines distributed in the infrastructures of many industrial applications has been very important since the industrial revolution. The guided ultrasonic wave technique can provide the possibility of rapid screening for corrosionin long pipelines. In particular the torsional mode T(0,1) of guided waves has been used for cases of buriedpipelines substantially. The function of being able to examine the inaccessible areas of pipelinesmakesthe guided ultrasonic wave technique highly favored among the non-destructive testing tools for pipeline inspection. This study investigated corrosion detection on pipelines using the guided wave technique. Examples of actual field cases including local corrosion, general corrosion, corrosion atwelds, cracks at welds and corrosion at welded supports are presented. For corrosion detection on pipelines, reflected signalsof the T mode symbolized the location and the estimated cross section change of the corroded portion, and those of the F mode symbolized the circumferential corrosion extent. The results of this study show that noticeable reflected signals of the F mode would indicate the presence of corrosion at the pipeline features qualitatively.