Applying Phased Array Ultrasonic Technique on Welds and Turbine Blades

[[abstract]]電廠之承壓設備，如火力電廠之鍋爐汽水鼓及壓力容器，核能電廠之反應爐冷卻水管路及蒸汽管路等，均屬發電系統上極為重要之關鍵設備。如電廠關鍵設備之接合銲道產生龜裂，而定期維修又無法有效檢出並加以改善，則可能導致銲道破裂，這將造成電廠營運上極大之工安危險及金錢損失，甚至因此可能危及公共安全。近幾年曾有民營電廠發生汽輪機轉子動葉片斷裂事故，損失極為慘重。耑此，如何開發新的檢測技術，提高檢測之有效性及可靠性，是我們刻不容緩的任務。另近年來，一般火力電廠運轉設備日益老化，目前正陸續進行延壽評估之改善工程，其中汽輪機轉子動葉片葉根及葉根槽之檢測係該項工程中極為重要的一環，其檢測技術相當複雜且準確度不易掌握，目前該特殊檢測工作仍有相當部分掌控在原製造廠商手上。 本論文旨在藉由比較相位陣列式超音波與傳統式超音波系統之差異，探討相位陣列式超音波檢測之優越性，並進而應用到電廠主要設備之銲道與汽輪機轉子動葉片葉根及葉根槽之檢測，希望能因此漸次掌控上述關鍵組件潛在瑕疵之檢測技術，以期能擺脫原製造廠商之技術壟斷，節省電廠之維護成本，進而減低營運意外發生之可能性。 經本論文實驗探討，證實相位陣列式超音波系統確具有傳統式超音波所缺乏之特點，大幅增加靈敏度及鑑別力，也印證適用於電廠關鍵設備接合銲道及汽輪機動葉片之檢測。[[abstract]]The Steam Drum and Pressure Vessel of Boiler in Fossil Power Plant and the Reactor Cooling Pipelines and Main Steam Piping in Nuclear Power Plant are essential components in Power Generation System. In the weld joint of the components, If the in-service thermal fatigue cracking induced by significant thermal stresses unable to be detected and removed from the components during periodical shut down overhauls. Thus it may lead to rupture and cause severe industrial accident. In the recent years, there had been several events of Turbine Blades failures in Power Plant. These events had not only resulted in enormous lost generation and expense and would cause the long-term of unscheduled outages of power plant. Therefore, we intend to develop and establish new inspection techniques to increase the availability and reliability of the welds and Steam Turbine Blades. This paper is to research the performance of the Phased Array Ultrasonic System and try to applying the system to welds of the essential components and Steam turbine blades in power plants. The experimental results confirmed that the Phased Array ultrasonic system has excellent performances over conventional ultrasonic system for inspecting pipeline welds and steam turbine blades