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Abstrak :
Sebuah perusahaan minyak dan gas di Subang, PT. X merupakan salah satu asset penting negara di Jawa Barat, dimana hasil produk dari perusahaan ini memberikan konstribusi terhadap perekonomian di pulau Jawa, khususnya di Jawa Barat. Input feed gas yang diperoleh PT. X ini memiliki konsentrasi CO2 cukup tinggi sebesar 23%, pemisahan CO2 removal dimaksudkan untuk mengurangi kandungan CO2 hingga kurang dari 5%. Hal ini karena CO2 dengan kadar > 5% sangat korosif tergantung pada tekanan (pressure) dan temperature. Proses pemurnian gas dilakukan oleh 2 unit identic CO2 removal, dimana sistem perpipaan menjadi penting untuk menyalurkan gas dari satu tempat ke tempat lain. Hasil analisa menunjukkan mekanisme kerusakan aktual pada pipa adala korosi CO2. Nilai laju korosi tertinggi sebesar 0,24 mm/year pada tahun 2020 karena adanya reaksi antara Fe dengan H2CO3 sebagai akibat dari perubahan temperature dan partial pressure CO2 model laju korosinya adalah Y = 0,0001x2 – 0,0297x + 1,5599 untuk pengaruh temperature dan Y = 9E-05x2 – 0,0228x + 1,5436 untuk pengaruh partial pressure CO2. Dari matriks kekritisan didapatkan 1-line number pada peringkat resiko medium high sehingga action yang perlu dilakukan adalah bersifat corrective maintenance dengan interval setiap 4 tahun sekali dan metode inspeksi nya adalah ultrasonic test. Hasil analisa kelayakan menunjukkan bahwa pipa yang diteliti masih layak beroperasi karena nilai MAWP masih di atas working pressure pipa tersebut. Model polynomial Y = 42,097x2 – 607,42x + 2724,8 sebagai model prediksi MAWP pada tahun 2025 mendatang dimana nilainya juga masih berada di atas working pressure sehingga masih layak digunakan sampai 2025. ...... An oil and gas company in Subang, PT. X is one of the important state assets in West Java, where the products of this company contribute to the economy on the Java, especially in West Java. Feed gas input obtained by PT. X has a high enough CO2 concentration up to 23%, the separation of CO2 removal us intended to reduce the CO2 content to less than 5%. This event is required due to CO2 concentration >5% is corrosive depending on pressure and temperature. The gas purification process is carried out by two identical CO2 removal unit, where the piping system is important to transfer gas from one place to another. The analysis result shows that the actual damage mechanism is CO2 corrosion. The highest corrosion rate value is 0,24mm/year in 2020, because of the reaction between Fe and H2CO3 as a result of changes in temperature and partial pressure CO2, the corrosion model is Y = 0,0001X2- 0,0297x + 1,5599 for the effect of themperature and Y = 9E-05X2 – 0,0228x + 1,5436 for the effect of CO2 partial pressure. From the critilically matrix, it is obtained one line number at the risk rating for medium high, so the action that need to be done is corrective maintenance at interval every 4 years and the inspection method is the ultrasonic test. The result of the feasibility analysis show that the pipe under study is still feasible to operate because the MAWP value still above the pipe’s working pressure. Polynomial model Y = 42,097x2 – 607,42x + 2724,8 as a prediction mode for MAWP in 2925 where the value also still above it it means the pipe still suitable for use until 2025.

Abstrak :
Korosi yang disebabkan oleh karbondioksida (CO2) pada pipa baja karbon dan peralatan di pengolahan minyak dan gas sangat umum terjadi. CO2 larut dalam air menghasilkan asam karbonat (H2CO3) yang mempunyai sifat yang lebih korosif dibanding asam klorida (HCL) pada pH yang sama. Electrochemical impedance spectroscopy dan linear polarization resistance digunakan untuk mengetahui fenomena proses yang terjadi selama proses adsorbsi inhibitor di permukaan logam. Variasi temperature dan konsentrasi dari inhibitor dilakukan untuk mengetahui kemampuan inhibisi inhibitor dan mekanisme inhibisi. Penelitian ini dilakukan pada baja karbon A106 grB di dalam lingkungan 3% NaCl. Konsentrasi inhibitor bervariasi dari 0,5,15, dan 40 ppm dan dengan variasi temperature di 40 0C dan 90 0C. Pada temperature 40 0C laju korosi menunjukan 213,9 MPY pada lingkungan tanpa penambahan inhibitor , dan akan turun drastis ke 22,4 MPY ketika 5 ppm inhibitor ditambahkan ke lingkungan, dengan effisiensi inhibisi 90%. Penambahan konsentrasi inhibitor sampai 40 ppm meningkatkan effisiensi inhibisi sampai 98%. Penambahan konsentrasi inhibitor berbasis Imidazoline dari dari 0 ppm sampai 5 ppm pada temperature 90 0C dapat menghasilkan penurunan laju korosi yang signifikan yaitu dari 173,3 MPY menjadi 31,67 MPY, dengan effisiensi inhibisi 82%. Dengan penambahan konsentrasi inhibitor sebanyak 40 ppm akan menaikan effisiensi inhibisi sampai 99,99 %. Mekanisme penghambatan laju korosi terjadi sebagai akibat terbentuknya ikatan polar (O-H dan N-H) yang berikatan dengan permukaan logam melalui proses chemisorption.

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Corrosion caused by carbon dioxide (CO2) in carbon steel pipes and equipment in oil and gas processing is very common. Water soluble CO2 produces carbonic acid (H2CO3) which has more corrosive properties than hydrochloric acid (HCL) at the same pH. Electrochemical impedance spectroscopy and linear polarization resistance are used to determine the processes that occur during the adsorbs inhibitor process on the metal surface. Variation of concentration of the inhibitor is conducted to determine the ability of inhibitor inhibition and inhibition mechanism. This research was conducted on A106 gr. B carbon steel in an environment of 3% NaCl. The inhibitor concentration varies from 0,5,15, and 40 ppm at 40 0C. At temperatures of 400C the corrosion rate shows 213.9 MPY in the environment without the addition of inhibitors, and will drop dramatically to 22.4 MPY when 5 ppm inhibitors are added to the environment. Electrochemical Impedance Spectroscopy is used to study inhibition mechanism. Increasing the concentration of Imidazoline based inhibitors from 0 ppm to 5 ppm at 90 0C can produce a significant decrease in corrosion rate from 173.3 MPY to 31.67 MPY, with 82% inhibition efficiency. With the addition of inhibitor concentrations up to 40 ppm will increase inhibition efficiency to 99,99 %. The mechanism of inhibition of corrosion rate occurs as a result of the formation of polar bonds (O-H and N-H) that bind to the metal surface through a chemisorption process.

Abstrak :
Material baja karbon merupakan material yang umum dipakai sebagai pipa penyalur, baik flowline maupun pipeline proses produksi gas alam. Penggunaan material baja pada proses tersebut seringkali menghadapi masalah yang berkaitan dengan korosi yaitu terjadinya kebocoran akibat pengaruh adanya gas CO2 yang terlarut dalam media air dan bersifat korosif (asam). Dalam upaya mengatasi masalah tersebut di atas, perlu diketahui besaran laju korosi material baja akibat pengaruh gas CO2 terlarut. Penelitian ini bertujuan untuk melakukan studi laju korosi material baja yang digunakan pada proses produksi gas alam yang mengandung CO2 dalam berbagai kondisi yang mewakili kondisi sesungguhnya di dalam aplikasi seperti pengaruh tekanan parsial CO2, komposisi larutan, dan temperatur. Penelitian dilakukan dengan metoda uji polarisasi. Hasil dari penelitian ini akan merefleksikan besaran laju korosi yang terjadi pada pipa penyalur gas alam akibat pengaruh CO2 terlarut. Laju korosi baja karbon pada lingkungan yang mengandung CO2 berkisar antara 15 - 28 mpy. Laju korosi yang tinggi ini akan membahayakan flowline dan pipeline penyalur gas alam sehingga dibutuhkan suatu metode proteksi untuk mencegah terjadinya kegagalan akibat proses korosi yang terjadi. Hasil dari penelitian ini merupakan tahap awal, sebagai bahan masukan untuk melakukan upaya penanggulangan (proteksi) agar tidak terjadi kebocoran flowline dan pipeline akibat korosi CO2 sesuai dengan umur pakai (life time) yang telah dirancang. ......Carbon steel is commonly used as flowline and pipeline in natural gas production process. However, the use of this steel often face problems related to corrosion, such as leakage due to effect of dissolved CO2 in water that causes corrosive environment (acid). In order to overcome this problem, further study must be carried out about corrosion rate model of this steel in dissolved CO2 condition. The aim of this research is to study corrosion rate of steel as flowline and pipeline in natural gas production process with CO2 content and variety of conditions that represent the actual conditions in practice such as CO2 partial pressure, solution composition, and temperature. Research conducted by polarization test. The result of this study will illustrate the level of corrosion rate occurred in natural gas pipelines due to the effect of dissolved CO2. Corrosion rate of carbon steel in environments containing CO2 ranged between 15-28 mpy. The high corrosion rate observed would damage natural gas transmission flowline and pipeline. Consequently, a protection method is required to prevent flowline and pipeline failure due to such corrosion. The result of this study is the first step, as an input for prevention efforts, to prevent leakage of flowline and pipeline due to corrosion of CO2 appropriate with the lifetime that has been designed.

Abstrak :
[ABSTRAK
Korosi memiliki dampak yang sangat besar terhadap ekonomi dan lingkungan pada berbagai infrastruktur, terkait dengan kegagalan operasi dan aset. Masalah yang umum terjadi pada jaringan pipa minyak dan gas saat ini adalah korosi internal yang disebabkan oleh media korosif yang umumnya mengandung karbon dioksida (CO2) dalam larutan aqueous. Karenanya, diperlukan cara untuk mengevaluasi korosi CO2 pada baja karbon terkait laju korosi agar dapat memenuhi umur operasi. Dalam penelitian ini, model Norsok yang telah dimodifikasi digunakan untuk memprediksi laju korosi pada lingkungan CO2, dan mempertimbangkan data parameter seperti suhu, tekanan parsial CO2, dan laju aliran untuk menghitung shear stress dan laju korosi. Software ini dibuat dengan menggunakan bahasa pemrograman visual basic (Microsoft Visual Studio ? VB), kemudian dengan menggabungkan basis pengetahuan mekanisme korosi CO2 dan aturan tertentu maka akan dihasilkan suatu sistem pakar. Berdasarkan perhitungan shear stress dan laju koros, kemudian rekomendasi dapat diajukan untuk mempertimbangkan, apakah baja karbon masih dapat digunakan atau penggunaan baja karbon dengan memberikan inhibitor atau penggantian baja karbon dengan Corrosion Resistance Alloys. Hasil perhitungan modifikasi model Norsok menunjukkan bahwa hasil perhitungan laju korosi tampak lebih realistis dibandingkan dengan model Norsok asli, dan dapat digunakan untuk mengevaluasi baja karbon yang mengalami korosi CO2 dengan tingkat kepercayaan lebih tinggi.

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ABSTRACT
Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident.;Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident., Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident.]

Abstrak :
ABSTRAK
Proses produksi Gas Alam yang umum dipakai sebagai pipa penyalur, baik flowline maupun pipeline biasanya menggunakan material baja karbon. Ada 3 faktor masalah besar dalam penggunaan material tersebut yang berkaitan dengan korosi yang biasanya terjadi pada proses tersebut. 3 faktor tersebut antara lain terjadinya kebocoran akibat pengaruh adanya gas CO2 yang terlarut dalam media air , adanya laju aliran fluida dalam pipa dan lingkungan bersifat korosif (asam). Dalam upaya mengatasi masalah tersebut di atas, perlu diketahui besaran laju korosi material baja akibat pengaruh gas CO2 terlarut. Penelitian ini bertujuan untuk melakukan studi laju korosi material baja yang digunakan pada proses produksi gas alam yang mengandung CO2 dalam berbagai kondisi yang mewakili kondisi sesungguhnya di dalam aplikasi seperti pengaruh tekanan parsial CO2, komposisi larutan, dan temperatur. Penelitian dilakukan dengan metoda uji polarisasi. Hasil dari penelitian ini akan merefleksikan besaran laju korosi yang terjadi pada pipa penyalur gas alam akibat pengaruh CO2 terlarut, variasi kecepatan putaran, dan pengaruh perubahan pH. Pada pH 5, laju korosi baja karbon pada lingkungan yang mengandung CO2 akan naik seiring dengan kenaikan laju aliran, tetapi begitu pH dinaikkan menjadi 6 laju korosi cenderung turun, suasana yang lebih basa dapat menurunkan laju korosi. Laju korosi yang tinggi ini akan membahayakan pipeline dan flowline penyalur gas alam. Hasil dari penelitian ini merupakan tahap awal, sebagai bahan simulasi yang terjadi pada pipa baja karbon pada proses produksi gas alam dan agar di kemudian hari dapat dicari upaya penanggulangannya dalam melawan 3faktor masalah besar tersebut sehingga dapat digunakan sesuai dengan umur pakai (life time) yang telah dirancang.

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ABSTRACT
Carbon steel is commonly used as flowline and pipeline in natural gas production process. There are 3 big causes on using that material which related to corrosion problem. The 3 factors such as leakage due to effect of dissolved CO2 in water that causes corrosive environment (acid),fluid's flow rate inside the pipeline, and acid environment. In order to overcome this problem, further study must be carried out about corrosion rate model of this steel in dissolved CO2 condition. The aim of this research is to study corrosion rate of steel as flowline and pipeline in natural gas production process with CO2 content and variety of conditions that represent the actual conditions in practice such as CO2 partial pressure, solution composition, and temperature. Research conducted by polarization test. The result of this study will illustrate the level of corrosion rate occurred in natural gas pipelines due to the effect of dissolved CO2, variation of rotation rate, and effect of pH. On PH 5, Corrosion rate of carbon steel in environments containing CO2 will increase along with the increase of flow rate, but when pH is increasing to 6, flow rate suddenly decrease, alkali(base) environment decreasing flow rate. The high corrosion rate observed would damage natural gas transmission pipeline and flowline. The result of this study is the first step, as a simulation things that happen in actual carbon steel, and hope in the future there are good protection method which can fight with these 3 big causes, so it can appropriate with the lifetime that has been designed.