石化廠球槽區管線包覆下腐蝕有效性檢測技術

Effective Corrosion Inspection Technique for CUI on Pipe in the Spherical Tank Dike

李秉鴻(Ping-Hung Lee)；黃啟貞(Chi-Jen Huang)；賴祐民(Yu-Min Lai)；王俊傑(Jun-Jie Wang)

球槽區管線 ； 包覆層下腐蝕 ； 防溢堤 ； 非破壞性檢測 ； Spherical Tanks ； Corrosion under Insulation ； Dike ； NDT

石油季刊

54卷4期（2018 / 12 / 01）

51 - 63

繁體中文

石化廠中為了存放製程上所需的各種原物料乃藉由建立球槽區將不同的原物料存放於各個球槽內部，經由管線來傳輸原物料至製程上各個單位，而球槽區管線大多採用保溫包覆於管線外部，因此管線包覆層下腐蝕（Corrosion under Insulation, CUI）為主要造成球槽區管線腐蝕、破管之原因；球槽區為了防止內容物洩漏造成重大損失，在每座球槽四周都以混凝土牆做為防溢堤，管線在球槽區間傳輸時便須穿越1.3公尺長的防溢堤，而防溢堤混凝土若有劣化時便會造成管線腐蝕的另外一項因素。本文乃以導波檢測法與數位輪廓射線照相進行球槽區包覆管線之CUI檢測，導波可檢測出主管上腐蝕包括局部腐蝕、均勻腐蝕與管支撐腐蝕，輪廓射線照相則負責檢出小插管與主管連接點的腐蝕程度；再以導波檢測法搭配定量電磁超音波針對防溢堤管線進行腐蝕檢測，導波可為防溢堤管線進行腐蝕快篩，評估出那一條管線具有較高之腐蝕風險，搭配電磁超音波可進行管線穿越防溢堤界面腐蝕之深度定量評估，綜合此三項非破壞性檢測技術，在拆除最少的包覆材料與不用開挖防溢堤的條件下，可為球槽區管線安全的管理提供一項有效性檢測方案。

In the petrochemical plant, the various spherical tank area are established to store the various raw materials required for the process. Pipelines with insulations are responsible for transfering raw materials to the process of the various units. Therefore, the corrosion under insulation (CUI) is the main cause of corrosion and pipe leakage in the dike. In order to prevent significant loss caused by leakage of contents, a concrete wall is used as an overflow prevention embankment around the spherical tank. When the pipeline go through the 1.3-meter-long concrete wall of the dike, the interface of the concrete wall is another area with high risk of corrosion. In this article, the guided wave testing and radiography testing profile are used to detect the corrosion under insulation. Guided wave testing is a technique used to inspect the local corrosion, general corrosion and corrosion under pipe clamp support. Radiography testing profile is used to evaluate the corrosion profile on the small vent or drain. Then, guided wave testing and QEUT are used to inspect and evaluate the corrosion at the interface of the dike. Combining the three NDT techniques, it is possible to provide an effective corrosion inspection program in the spherical tank area with removing the least dismantling of the insulation material.

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