Desain dan Analisis Kehandalan Pipa Bawah Laut Pada Kondisi Instalasi Akibat Keacakan Tinggi Gelombang dan Kuat Leleh Baja

Andika Razandi Ibrahim, Paramashanti Paramashanti

Abstract


Demi mencapai metoda distribusi migas yang efisien, pipa bawah laut harus didesain agar dapat memenuhi tujuan desain selama masa layan. Pada proses desain digunakan data deterministic berupa tinggi gelombang signifikan dan kuat leleh baja desain. Pada studi ini proses desain dilakukan sesuai dengan standar DNV OS F101 dan DNV RP E305 untuk pipa dengan diameter 32 inci. Pada kondisi aktual saat proses instalasi, pipa mengalami tegangan yang diakibatkan oleh gelombang acak. Serta nilai desain kuat leleh baja yang digunakan merupakan hasil pengolahan dari banyak data acak uji tarik sampel baja. Oleh karena itu dilakukan analisis kehandalan menggunakan simulasi Monte Carlo untuk mengetahui efek dari keacakan tinggi gelombang dan kuat leleh baja terhadap tegangan yang terjadi disepanjang pipa. Simulasi Monte Carlo dilakukan sebanyak 100 simulasi untuk 3 (tiga) arah datang gelombang. Pada proses analisis kehandalan, pipa dianggap gagal apabila nilai tegangan total maksimum yang terjadi lebih besar atau sama dengan nilai kuat leleh. Berdasarkan hasil simulasi didapat kesimpulan bahwa pipa dinyatakan tidak handal karena memiliki nilai probabilitas kehandalan kurang dari 0.998.

 

In order to achieve an efficient oil and gas distribution method, subsea pipelines must be designed to meet design goals during service life. In term of design process, deterministic data used in form of significant wave height and steel yield strength. In this study, the design process carried out according to DNV OS F101 and DNV RP E305 standards for pipeline with 32 inches outer diameter. In actual conditions during the installation process, tensions applied along the pipeline as effect from random waves. Also the design value of design steel yield strength is a result from many random tensile test value of steel samples. Therefore, reliability analysis carried out using Monte Carlo simulation to determine the effect of random wave heights and steel yield strengths on the stress occurred along pipeline. Monte Carlo simulation are carried out as many as 100 simulations for each of three wave headings. In reliability analysis, pipeline is considered fail if the maximum total stress that occurs is greater or equal to its yield strength. Based on the simulation results, pipeline considered unreliable due to its reliability probability value which is lower than 0.998.

 


Keywords


Instalasi pipa bawah laut, Analisis kehandalan, Monte Carlo

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References


Det Norske Veritas, 2013, DNV OS F101 Submarine Pipeline Systems. Norwegia : Det Norske Veritas.

Det Norske Veritas, 2013, DNV RP E305 On-Bottom Stability Design of Submarine Pipelines. Norwegia : Det Norske Veritas.

Haldar, Achintya dan Sankaran Mahadevan, 2000, Probability, Reliability, and Statistical Methods in Engineering Design. New York : John Wiley & Sons, Inc.

Hess, Paul E. et. al, 2002, Uncertainties in Material Strength, Geometric, and Load Variables. American Society of Naval Engineers.

Ochi, Michel K. 1998. Ocean Waves : The Stochastic Approach. Cambirdge : Cambridge University Press.




DOI: http://dx.doi.org/10.5614%2Fjts.2019.26.2.7

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