Analisis Laju Korosi dan Lifetime pada Pipa API 5L Grade B dengan Perbandingan Inhibitor NaNO₂ dan NaNO₃ Menggunakan Metode Immersion Test
The oil and gas company in Gresik experienced internal corrosion in one of its pipes, the crust clumping inside the pipe which resulted in a decrease in oil production that had to be distributed. The pipe used is API 5L Grade B with a diameter of 4 inch Sch 40. This study uses the Immersion Test method to determine the corrosion rate and lifetime by calculating weight loss and comparing NaNO₂ and NaNO₃ inhibitors. This test has three variations of HNO₃ concentration of 700 ppm, 800 ppm and 900 ppm. The variation of inhibitor concentration is 0 ppm, 150 ppm and 300 ppm. And using 2 temperature variations of 30°C and 40°C. The test results showed that the lowest corrosion rate using NaNO₂ inhibitors was 0.0697 mm/y. While NaNO₃ inhibitors have the lowest corrosion rate of 0.0712 mm/y. The highest value of inhibitor efficiency is NaNO₂ inhibitor of 0.243%. And the lifetime calculation for NaNO₂ inhibitors is 65.79 years and 64.41 years for NaNO₃ inhibitors. So the best corrosion protection method for API 5L Grade B is to use NaNO₂ inhibitors because it has the lowest corrosion rate and a longer service life.