Kajian Sisa Umur Pakai dan Proteksi Katodik Sistem Anoda Korban Pada Pipa Transportasi Gas Pipeline C di Kecamatan Cilamaya Wetan, Kabupaten Karawang, Provinsi Jawa Barat

Abstract

Abstract. Transportation activities in the gas and crude oil industry use metal-based pipes. The metals used in transportation pipes have good resistance to high pressure and high temperature properties. However, metal pipes experience corrosion due to their interaction with the environment. The environment is in the form of land, water, air, natural gas and crude oil. The disadvantage of corrosion is that it results in a reduction in the thickness of the pipe, resulting in pipe leakage and the remaining life of the pipe is low. Therefore, it is necessary to monitor corrosion on pipes, one of which is through this study so that the remaining useful life of the pipes can reach its design life. This research was conducted on a gas transportation pipe along 1,764 meters below ground level. This study aims to determine the type of corrosion, the degree of cathodic protection of the sacrificial anode system, the corrosion rate and the remaining useful life of gas transportation pipes as well as the external environmental factors that influence it. The methodology in this research is the measurement of pipe thickness reduction to determine the corrosion rate and the remaining useful life of the pipe based on API 570. Measurement of pipe thickness using the Ultrasonic Thickness Gauge Panametrics MG 2 DL at 8 points. Environmental conditions in the research area, namely soil pH 5.8 - 6.2, including the acid category with gray alluvial soil type, average air temperature 27⁰C, and soil resistivity 1,904 - 1,929 ohm.cm included in the very corrosive level of corrosivity. The types of corrosion that occur in gas transportation pipes are uniform corrosion and erosion corrosion. External environmental factors, namely soil pH and soil resistivity, have no significant effect on the corrosion rate and the remaining useful life of the pipe because the coating, wrapping, and cathodic protection of the sacrificial anode system are still functioning properly. The value of the cathodic protection potential of the sacrificial anode system ranges from -1,067 to -983 mV vs CSE which is included in the level of protection, which is protected according to the NACE RP0169 standard. The pipe corrosion rate, which ranges 0.2050 - 0.2230 mm/year, is included in the good category based on the relative corrosion resistance of steel. The service life of the pipe is 20 years and the remaining useful life of the pipe is 4.66 - 6.83 years, this shows that the pipe can be used beyond the design life of the pipe (20 years).

Keywords: Carbon Steel Pipes, Gas, Cathodic Protection, Corrosion Rate, Remaining Service Life.

Abstrak. Kegiatan transportasi pada industri gas dan crude oil menggunakan pipa berbahan dasar logam. Logam yang digunakan pada pipa transportasi memiliki sifat ketahanan yang baik terhadap tekanan dan temperatur tinggi. Akan tetapi, pipa logam mengalami korosi akibat berinteraksi dengan lingkungan. Lingkungan tersebut berupa tanah, air, udara, gas bumi, dan crude oil. Kerugian terjadinya korosi yaitu mengakibatkan pengurangan ketebalan pipa, sehingga mengalami kebocoran pipa dan sisa umur pakai pipa menjadi rendah. Oleh karena itu, diperlukan monitoring korosi pada pipa salah satunya melalui kajian ini agar sisa umur pakai pipa dapat mencapai umur desainnya. Penelitian ini dilakukan pada pipa transportasi gas sepanjang 1.764 meter yang berada di bawah permukaan tanah. Penelitian ini bertujuan untuk mengetahui jenis korosi, tingkat proteksi proteksi katodik sistem anoda korban, laju korosi pipa dan sisa umur pakai pipa transportasi gas serta faktor-faktor lingkungan eksternal yang mempengaruhinya. Metodologi dalam penelitian ini yaitu pengukuran pengurangan ketebalan pipa untuk mengetahui laju korosi dan sisa umur pakai pipa berdasarkan API 570. Pengukuran ketebalan pipa menggunakan alat Ultrasonic Thickness Gauge Panametrics MG 2 DL pada 8 titik. Kondisi lingkungan di daerah penelitian ini yaitu  pH tanah 5,8 – 6,2 termasuk kategori asam dengan jenis tanah aluvial kelabu, temperatur udara rata-rata 27⁰C, dan resistivitas tanah 1.904 – 1.929 ohm.cm termasuk ke dalam tingkat korosifitas sangat korosif. Jenis korosi yang terjadi pada pipa transportasi gas yaitu korosi merata dan korosi erosi. Faktor-faktor lingkungan eksternal yaitu pH tanah dan resistivitas tanah tidak berpengaruh signifikan terhadap laju korosi dan sisa umur pakai pipa karena coating, wrapping, dan proteksi katodik sistem anoda korban masih berfungsi dengan baik. Nilai potensial proteksi katodik sistem anoda korban berkisar antara    -1.067 sampai -983 mV vs CSE yang termasuk ke dalam tingkat proteksi yaitu terproteksi berdasarkan standar NACE RP0169. Laju korosi pipa yaitu berkisar antara 0,2050 – 0,2230 mm/tahun termasuk ke dalam kategori good berdasarkan ketahanan korosi relatif baja. Umur pakai pipa 20 tahun dan sisa umur pakai pipa yaitu 4,66 – 6,83 tahun, hal ini menunjukkan bahwa pipa dapat digunakan melebihi umur desain pipa (20 tahun).

Kata Kunci: Pipa Baja Karbon, Gas, Proteksi Katodik, Laju Korosi, Sisa Umur Pakai.