Analisis Kegagalan Reheater Radiant Wall Tube pada Unit Subcritical Boiler PT.X

'Adhim, Muhammad Aldi Luthfi Fauzan (2023) Analisis Kegagalan Reheater Radiant Wall Tube pada Unit Subcritical Boiler PT.X. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pembangkit Listrik Tenaga Uap (PLTU) berbasis bahan bakar fosil saat ini masih merupakan penyuplai energi listrik utama di Indonesia. Batubara merupakan bahan bakar pembangkit listrik yang sangat umum digunakan pada proses PLTU di Indonesia, salah satu tipe boiler yang umum digunakan yaitu boiler subcritical. Pada tanggal 22 April 2022 , dilakukan shutdown. unit boiler untuk inspeksi rutin pada komponen. Dari hasil inspeksi ditemukan adanya kebocoran pada pipa Reheater Radiant Wall. Titik bocor yang ditemukan terletak di sisi belakang pada sambungan pelat fin spacer dengan tube reheater.Komponen tersebut dilaporkan telah beroperasi selama 25 tahun dengan material tube berupa baja karbon ASTM A210-Grade A1 dan Fin berupa ASTM A387-Grade 12 Class 2 . Sebelum kegagalan terjadi, dilaporkan bahwa tube Reheater Radiant Wall sempat mengalami proses pelepasan dan pemasangan sambungan fin pada periode shutdown sebelumnya. Untuk itu, diperlukan analisis root cause kegagalan pada komponen Reheater Radiant Wall untuk menghindari kegagalan dengan mekanisme serupa. Beberapa pengujian karakterisasi seperti Uji Komposisi (OES), XRD, metalografi, uji potensiodinamik polarisasi, dan uji kekerasan dilakukan untuk mendukung hasil analisis.Uji potensiodinamik menunjukkan nilai potensial tube (-0.47 V) yang cenderung lebih rendah dibandingkan fin (-0.42 V). Hasil uji metalografi dan kekerasan menunjukkan indikasi terbentuknya fasa bainit pada daerah sekitar kebocoran dan nilai kekerasan yang terlampau tinggi (277.367-313.267 HV) dibandingkan di sekitar daerah jauh dari zona kebocoran (126.667-132.467 HV) Mekanisme kegagalan diinisiasi oleh kombinasi antara korosi celah dan galvanic coupling.Korosi celah mulanya terjadi pada sisi belakang sambungan las sehingga menimbulkan kerusakan/defect awal baik pada tube maupun fin yang terlokalisasi. Di samping itu, defect ini juga diperparah oleh Galvanic coupling ,terutama pada sisi tube yang cenderung lebih bersifat anodik.Mekanisme ini terus berlangsung hingga akhirnya defect menembus dinding tube dan terjadi kebocoran.
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Fossil fuel-based steam power plants are still the main supplier of electricity in Indonesia. One of them is subcritical boiler unit, which uses a subcritical-type boiler in the process. On April 22, 2022, the subcritical boiler unit shut down was carried out for routine inspection of components. From the inspection results, it was found that there was a leak in the Reheater Radiant Wall tube. The leak point found was located on the rear side of the fin spacer plate weld joint with the tube. This component is reported to have been in operation for 25 years, with the tube material being carbon steel ASTM A210-Grade A1 and the fin being ASTM A387-Grade 12 Class 2. Prior to the failure, it was reported that the Reheater Radiant Wall tube had undergone the process of removing and installing fin connections during the previous shutdown period. For this reason, it is necessary to analyze the root cause of failure in the Reheater Radiant Wall component to avoid failure with a similar mechanism. Several characterization tests, such as the composition test (OES), XRD, metallography, polarization potentiodynamic test, and hardness test, were carried out to support the analysis results. The potentiodynamic test showed that the tube potential value (-0.47 V) was lower than the fin potential value (-0.42 V). Metallographic and hardness test results showed the formation of a bainite phase in the area around the leak, and the hardness value was too high (277.367–313.267 HV) compared to the area far from the leak zone (126.667–132.467 HV). The failure mechanism was initiated by a combination of crevice corrosion and galvanic coupling. Crevice corrosion initially occurs on the back side of the unwelded area, causing localized initial damage or defects to both the tube and the fin. In addition, this defect is also exacerbated by Galvanic coupling, especially on the tube side, which tends to be more anodic in nature. These mechanism combination would be continued until the leak occured.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Boiler, Crevice Corrosion, Galvanic Coupling, Failure Analysis, Reheater Tube,Analisis Kegagalan, Boiler, Galvanic Coupling, Korosi Celah, Reheater Tube
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA169.5 Failure analysis T Technology > TA Engineering (General). Civil engineering (General) > TA467 Iron and Steel Corrosion and protection against corrosion
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Material & Metallurgical Engineering > 28201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Aldi Luthfi Fauzan 'adhim
Date Deposited:	26 Jul 2023 04:31
Last Modified:	26 Jul 2023 04:31
URI:	http://repository.its.ac.id/id/eprint/99293

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