Analisis Kegagalan Shaft Main Oil Pump AISI 1045 Pada Steam Turbine PT. X

Jan, Nazamuddin Isra (2025) Analisis Kegagalan Shaft Main Oil Pump AISI 1045 Pada Steam Turbine PT. X. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5011211132_Undergraduate_Thesis.pdf Restricted to Repository staff only until 5 August 2025. Download (8MB) | Request a copy

Abstract

Main Oil Pump merupakan pompa sentrifugal yang memanfaatkan gaya sentrifugal melalui impeller yang berputar untuk memindahkan Oli dari Oil Tank menuju ke Steam Turbine Pada
tanggal 23 April 2024, terjadi fraktur poros secara tiba-tiba tanpa tanda-tanda anomali mekanis sebelumnya, meskipun poros tersebut baru dipasang dan beroperasi hanya selama 8 jam. Karakterisasi material mengidentifikasi poros tersebut sebagai baja karbon sedang AISI 1045. Namun, analisis kimia menunjukkan kandungan fosfor sebesar 0,17%, yang secara signifikan melebihi batas spesifikasi ASTM A576-90b sebesar 0,04%.Pemeriksaan mikrostruktur menunjukkan matriks ferit-perlit, sementara pengamatan fraktografi melalui SEM dan
stereomikroskopi mengidentifikasi beberapa titik awal retakan di sekitar alur pasak. Pola perambatan menunjukkan tanda ratchet, morfologi fraktur intergranular, dan tanda radial yang konsisten dengan kegagalan fatik. Jalur retakan dari zona inisiasi A dan B menyatu di zona C sebelum mencapai keruntuhan akhir di zona D. Analisis EDX mengonfirmasi adanya segregasi fosfor pada permukaan patahan (2,4% massa), yang berkontribusi terhadap embrittlement batas butir.Analisis Elemen Hingga (FEA) menunjukkan tegangan ekuivalen maksimum sebesar 19,93 MPa—jauh di bawah rentang batas ketahanan yang diharapkan untuk AISI 1045 (131-220 MPa). perbedaan ini menunjukkan bahwa segregasi fosfor merupakan faktor kritis yang mendorong kegagalan. Mekanisme kegagalan dipengaruhi oleh konsentrasi tegangan lokal pada keyway, yang menyebabkan inisiasi retak, intergranular crack, yang menyebabkan kegagalan dapat terjadi
========================================================================================================================
The Main Oil Pump is a centrifugal pump that utilizes centrifugal force through a rotating impeller to move oil from the oil tank to the steam turbine. On April 23, 2024, a shaft fracture occurred suddenly without any prior signs of mechanical anomalies, even though the shaft had been newly installed and in operation for only 8 hours. Material characterization identified the shaft as AISI 1045 medium carbon steel. However, chemical analysis revealed a phosphorus content of 0.17%, significantly exceeding the ASTM A576-90b specification limit of 0.04%. Microstructural examination revealed a ferrite-pearlite matrix, while fractographic observations via SEM and stereomicroscopy identified multiple crack initiation points around
the keyway. The propagation pattern showed ratchet marks, intergranular fracture morphology, and radial mark consistent with fatigue failure. The crack paths from initiation zones A and B coalesced in zone C before reaching final failure in zone D. EDX analysis confirmed the
presence of phosphorus segregation on the fracture surface (2.4% by mass), which contributed to grain boundary embrittlement. Finite Element Analysis (FEA) indicated a maximum equivalent stress of 19.93 MPa—well below the expected endurance limit range for AISI 1045 (131–220 MPa). This difference indicates that phosphorus segregation was a critical factor driving failure. The failure mechanism was influenced by local stress concentrations in the keyway, which led to crack initiation, intergranular cracking, and subsequent failure.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Fraktographi, Analisis SEM, Pompa Oli Utama, Analisis Elemen Hingga Fractography, SEM Analysis, Main Oil Pump, Finite Element Analysis
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ919 Centrifugal pumps--Design and construction.
Divisions:	Faculty of Industrial Technology > Material & Metallurgical Engineering > 28201-(S1) Undergraduate Thesis
Depositing User:	Nazamuddin Isra Jan
Date Deposited:	04 Aug 2025 03:55
Last Modified:	04 Aug 2025 03:55
URI:	http://repository.its.ac.id/id/eprint/126895

Actions (login required)

View Item