全世界各國的石化工業煉油廠，為了存載大量的原料油而興建了大型儲存槽設備，但儲存槽的存在也對工業安全帶來潛在的隱憂，若儲存槽沒有完善的管理與檢測，可能會使油料洩漏，造成環境嚴重的污染，也會導致失火及儲存槽爆炸的事故，造成嚴重的石化工安意外。儲存槽內部底板的腐蝕，正是發生油料洩漏的主因，但在傳統的儲存槽底板檢測中，需要進入儲存槽內部進行相當繁複的檢測程序，而且檢測人員在入槽檢測的期間可能會造成不必要的危險。本研究係應用相位陣列超音波檢測技術於儲存槽底板關鍵區域進行檢測，相位陣列超音波探頭架設於儲存槽底板外部，檢測者不用進入槽內即可針對儲存槽底板之腐蝕進行檢測。相位陣列超音波具有獨特多陣元探頭激發聲波技術，可對特殊的幾何形狀控制聲波入射的角度與聚焦距離等能力，故能夠從外部的底板以多次反射法進行扇形掃描的檢測。本論文以實驗探討儲存槽底板關鍵區域中不同尺寸的孔蝕群檢測結果以及檢出的極限範圍，將檢出結果以不同的掃描成像視圖進行比較，說明檢測的成因以及相位陣列超音波系統的檢測優勢。
　　研究結果顯示，本系統能夠搭配超音波編碼器將儲存槽底板之孔蝕群缺陷即時成像於C-Scan訊號圖中，在訊號圖中可以分辨底板銲道與缺陷位置，缺陷的實際孔徑也能量測出來。本研究亦使用相位陣列超音波系統以S-Scan訊號圖成像出孔蝕缺陷的剖面情形，而缺陷的垂直角隅及錐角的特徵訊號能夠用來判定缺陷的深度，且能檢測出深度1.5 mm以上的孔蝕缺陷；以此方法進行缺陷的定量評估可以探討缺陷的幾何形狀以及缺陷與探頭的距離對於檢測能力的影響。本論文證明了相位陣列超音波系統應用在儲存槽外部檢測儲存槽底板關鍵區域的優勢，使得儲存槽的安全能夠有更可靠的保障。

The main purpose of constructing the oil tank equipment in petrochemical refineries around the world is to store a lot of oil. However, if there were not providing the perfect security inspection for oil storage tank, the corrosion may cause the oil leaks and lead to the serious petrochemical industrial accident. In the conventional method for detecting bottom of oil tank, the inspectors need to go into the storage tank to conduct the complicated detection. However, the inspectors may be exposed to hazardous when they are on the inside of oil tank. The purpose of this thesis is to apply the phased array ultrasonic method to detect critical zone at the bottom of the tank. Consequently, inspectors can install the phased array ultrasonic transducer at the bottom of outside oil tank for detecting the corrosion directly rather than go to the inside of oil tank. In this thesis experiment is performed by the phased array ultrasonic method that can pulse multiple element transducers to detect the different sizes of pitting corrosion area in the critical zone of oil tanks and to discuss the experimental result and limit. The experimental results are scanned into different images to be compared to explain the causes of the test and the advantages of phased array ultrasonic system detection.
　　The results indicated that by using the phased array ultrasonic system combined with encoder could make the pitting corrosion area in the bottom of oil tank to image instantly on the signal of C-Scan and it could distinguish the site of the bottom welds and the defect, could also measure the diameter of the pitting corrosion. For the signal of S-Scan, it could image the cross-sectional of pitting corrosion; moreover the signal feature of vertical corner and corner angle of the defect can be used to determine the depth of defect, the minimum of depth is 1.5 mm. By the quantitative evaluation of the defect could discuss the defect geometry and the distance from the transducer to defect having an effect on the detection results. This thesis proves that applying the phased array ultrasonic system of detecting the critical zone from the outer oil tank has its advantage. Moreover, this method provided more security to the oil tank.

誌謝 i
中文摘要 ii
英文摘要 iii
目錄 v
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 5
1.3 研究目的 6
1.4 研究方法 7
1.5 論文結構 8
第二章 相位陣列超音波原理 12
2.1 超音波 12
2.2 超音波的掃描形式 13
2.3 相位陣列超音波 14
2.4 扇形掃描反射原理 18
第三章 實驗方法與量測 28
3.1 相位陣列超音波檢測系統 28
3.2 實驗試件製作 29
3.3 量測校正 31
3.4 實驗設定與步驟 33
第四章 實驗結果與討論 51
4.1 標準塊規特徵辨識 51
4.2 缺陷深度的檢出靈敏度 52
4.3 銲接處無缺陷之量測 56
4.4 孔蝕缺陷的檢出能力 57
4.5 均勻腐蝕缺陷之實務驗證 58
第五章 結論與未來展望 81
5.1 結論 81
5.2 未來展望 82
參考文獻 84

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