Clarensia, Bella (2021) Analisis Tegangan Pipa Dan Dimensi Concrete Support Pada Daerah Crossing Akibat Free Span Pada Crossing Pipeline Milik PT.X Di Gulf Of Mottama. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Transportasi minyak dan gas menggunakan salah satunya pipa bawah laut dikarenakan efektifivitasnya yang tinggi serta ekonomis. Namun, hal ini tidak terlepas dari resiko yang dapat terjadi salah satunya fenomena free span. Fenomena ini merupakan kondisi di mana pipa tidak memiliki kontak dengan dengan seabed dan mengakibatkan terdapatnya jarak antar kedua bagian tersebut. Kejadian ini terjadi salah satunya pada kondisi crossing pipeline di mana terdapat lebih dari satu pipa yang melewati satu titik yang sama. Kondisi ini berbahaya bagi pipa yang beroperasi diakibatkan dapat terjadinya Vortex Induced Vibration akibat terbentuknya resonansi vortex shedding yang terbentuk di sekitar pipa dan menyebabkan perubahan tekanan secara periodik pada sekitar pipa. Dilakukan mitigasi pada kondisi free span akibat crossing pipelines dengan menggunakan concrete support dengan tepat agar mampu menopang pipa dengan aman. Dari hasil perhitungan, hasil analisis untuk tegangan yang terjadi pada pipa
tidak melebihi nilai allowable stress, dengan nilai hoop stress 73,71 N/mm2 dan nilai allowable stress sebesar 225 N/mm2, untuk nilai maximum longitudinal stress sebesar 317 N/mm2 dengan allowable stress sebesar 360 N/mm2, dengan nilai maximum combined stress ratio sebesar 374,48 N/mm2 dengan allowable stress sebesar 405 N/mm2. Didapatkan juga hasil analisis displacement tidak melebihi batas yang diijinkan dengan nilai batas yang
diijinkan sebesar 220,6 mm. Didapatkan juga besar dimensi support yang sesuai dengan tinggi concrete support sebesar 1,4 m.
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Oil and gas transportation uses, one of it, subsea pipelines due to it’s high effectiveness and
economy. However, this is inseparable from the risks that can occur, one of which is the free span
phenomenon. This phenomenon is a condition where the pipe does not have contact with the seabed
and results in a distance between the two parts. This incident may occurred in the crossing pipeline
condition where there is more than one pipe passing through the same point. This condition is
dangerous for the pipe operating due to the occurrence of Vortex Induced Vibration due to the
formation of vortex shedding resonance that forms around the pipe and causes periodic pressure
changes around the pipe. Mitigation is carried out in the free span condition due to crossing pipelines
by using concrete support appropriately to be able to safely support the pipe. From the calculation
results, the analysis results for the stress that occurs in the pipe does not exceed the allowable stress
value, with a hoop stress value of 73.71 N/mm2 and an allowable stress value of 225 N/mm2, for a
maximum longitudinal stress value of 317 N/mm2 with an allowable stress of 360 N/mm2, with a
maximum combined stress ratio of 374.48 N/mm2 with an allowable stress of 405 N/mm2. It is also
found that the results of the displacement analysis do not exceed the allowable limit with the
allowable limit value of 220.6 mm. The dimensions of the support are also found to match the height
of the concrete support of 1.4 m.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | pipelines, subsea, pipeline crossing, free span, concrete support |
| Subjects: | T Technology > TC Hydraulic engineering. Ocean engineering |
| Divisions: | Faculty of Marine Technology (MARTECH) > Marine Engineering > 36202-(S1) Undergraduate Thesis |
| Depositing User: | Bella Clarensia |
| Date Deposited: | 08 Sep 2021 07:42 |
| Last Modified: | 25 Jul 2024 03:12 |
| URI: | http://repository.its.ac.id/id/eprint/91810 |
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