Keandalan Crane Pedestal's Scantling FPSO Belanak Terhadap Beban Kelelahan

Prasetyo, Dhani Trie (2010) Keandalan Crane Pedestal's Scantling FPSO Belanak Terhadap Beban Kelelahan. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 4305100054-Undergraduate_Thesis.pdf - Accepted Version Download (26MB)

Abstract

FPSO (Floating Production Storage and Offloading) dalam operasinya mendapatkan pengaruh signifikan dari beban lingkungan dan operasionalnya. Hal demikian juga akan mempengaruhi komponen-komponen struktur yang ada di atasnya, termasuk struktur crane dan pedestalnya yang berfungsi sebagai fasilitas transfer logistik. Konstruksi crane pedestal beserta scantlingnya yang tersambung menerus ke lambung FPSO haruslah kuat menahan beban-beban yang terjadi, yang pada dasarnya bersifat siklis. Sehubungan dengan ini perancang harus dapat menentukan kekuatannya menahan beban siklis yang akan menimbulkan kelelahan pada scantling crane pedestal. Dalam penelitian ini kelelahan scantling crane pedestal telah dikaji dengan metode deterministik-spektral dan metode probabilistik atau keandalan. Pada pengkajian dengan metode deterministikspektral penyelesaian dilakukan dengan mengaplikasikan persamaan kegagalan kumulatif, sedangkan pengkajian keandalan menggunakan simulasi Monte Carlo. Analisis dimulai dengan penentuan beban dinamis Iingkungan menggunakan perangkat lunak MOSES, serta penentuan tegangan lokal pada semua tingkat beban siklis menggunakan perangkat lunak ANSYS. Penelitian dilakukan pada scantling crane pedestal pada FPSO Belanak yang berukuran diameter 5.0 m pada bagian bawah dan 3.0 m pada bagian atas, dengan tinggi keseluruhan 42.8 m, mempunyai massa 251 ton. Beban siklus dari gelombang, angin dan operasional diakumulasi dari beban terendah sampai dengan tertinggi. Hasil analisis menunjukkan kontribusi beban terhadap umur kelelahan crane pedestal scantling FPSO Belanak berturut-turut dari yang terbesar adalah disebabkan oleh beban gelombang yakni sebesar 97.84%, beban operasional atau beban angkat crane sebesar 2.16%, dan beban angin sebesar 0.000000269 %. Umur kelelahan dari crane pedestal scantling FPSO Belanak adalah 109.309 tahun atau 3.64 kali umur operasinya. Keandalan terhadap beban kelelahan dari crane pedestal scantling FPSO Belanak berdasarkan perhitungan menggunakan simulasi Monte Carlo adalah 1.0, yakni baik terjadi pada struktur global maupun area kritis pada daerah sambungan antara crane pedestal dengan bracket. Nilai-nilai tersebut memperlihatkan bahwa crane pedestal scantling mempunyai keandalan yang tinggi dan akan aman dioperasikan sesuai dengan umur rancangannya.
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FPSO (Floating Production Storage and Offloading) in its operation is significantly affected by the environmental a-. well as operational loads. Similarly this would also affect the structural components onboard of the FPSO, including the crane and its pedestal structures which are preserved as the logistic transfer equipments. The crane pedestal structure together with the scantlings that extend to the FPSO hulls should be sufficiently strong to endure the loads, which are fundamentally cyclic in nature. In this regards a desig1fer should be able to design the structure against cyclic loads which in turn would result in a fatigue failure on the crane pedestal scantling. In this investigation the fatigue performance of crane pedestal scantling has been evaluated through the implementation of spectral-deterministic and probablistic or reliability methods. In the spectral-deterministic method analysis is tackled by using the cumulative damage fatigue equation, whereas the reliability evaluation is accomplished by means of Monte Carlo simulation. Analysis was commenced by the determination of dynamic loads employing the MOSES software, followed by the determination of local stresses at any level of cyclic load utilizing software ANSYS. Investigation has been carried out on the crane pedestal scantling attached to the Belanak FPSO sized 5. 0 m diameter at the lower part and 3. 0 m diameter on its upper part, having a total height of 42.8 m, with a total mass of 25I tons. The cyclic loads due to wave, wind and operational are accumulated all together from the lowest up to the highest level. Result of the analysis shows the contribution of the loads on the fatigue life are, respectively, from the largest are due to wave in the range of 97.84%, due to operational or lifting load of 2.16% and due to wind is as low as 0. 000000269%. The fatigue life of the crane pedestal scantling is finally found to be 109.309years or 3.64 times its designed lifetime. The Belanak FPSO crane pedestal scantling reliability against fatigue failure eventually is achieved as high as 1.0, both at the global as well as at the local critical structures. This fact suggests the crane pedestal scantling preserves a high reliability and would be immensely safe to be operated in accordance with its designed lifetime

Item Type:	Thesis (Other)
Additional Information:	RSKe 621.873 Pra k 2010
Uncontrolled Keywords:	crane pedestal scantling, kelelahan, FPSO, keandalan; scantling pedestal cranes, fatigue, FPSO, reliability
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ1363 Cranes, derricks, etc.
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Totok Setiawan
Date Deposited:	26 Jan 2024 02:29
Last Modified:	26 Jan 2024 02:29
URI:	http://repository.its.ac.id/id/eprint/105641

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