Pengaruh Variasi Konsentrasi Asam Sulfat dalam Air terhadap Laju Penipisan Pipa Stainless Steel 316L pada Proses Regenerasi Air Demin di PT Pertamina EP Cepu

Abstract

This study aims to analyze the corrosion rate (wall thinning) in stainless steel 316L pipes due to exposure to diluted sulfuric acid across various concentrations: 3%, 7%, 11%, and 15%. The testing was conducted using the weight loss method (ASTM G31-72), with samples immersed for 38 days at room temperature.

The results indicate that increasing the concentration of sulfuric acid significantly escalates the corrosion rate of SS 316L. This increase in acid concentration raises the amount of hydrogen ions H⁺ which accelerates the metal's oxidation reaction and damages the passive chromium oxide Cr₂O₃ layer on the surface.The measured corrosion rates for 3%, 7%, 11%, and 15% concentrations were 0.0238 mm/year, 0.0397 mm/year, 0.0477 mm/year, and 0.0874 mm/year, respectively. Based on these findings, the SS 316L material still demonstrates good corrosion resistance (low corrosion rate) at sulfuric acid concentrations 7%. However, at concentrations 11%, a rapid increase in the corrosion rate occurred, indicating degradation of the passive layer and increasing the long-term risk of pipe thinning and leakage. Therefore, strict concentration control is highly recommended to prolong the service life of pipes in the demin water regeneration operational environment.