Perpustakaan Digital ITB

This study evaluated the corrosion of API 5L X80 steel under stratified smooth and slug flow in chemically mimicked CO?-saturated brine. The test electrolyte was 1 mol/kg NaCl solution at pH 3.99. Static immersion for 3 days was used as a baseline condition, while dynamic exposures of 1 to 2 hours were performed in a horizontal gas-liquid flow loop. Flow mapping identified six major horizontal flow patterns, from which stratified smooth and slug flow were selected for corrosion testing. The corrosion rates were calculated by coupon weight loss and total-iron concentrations measured with Hanna HI97721 Photometer based on the 1,10-phenanthroline method. The weight-loss corrosion rate under static conditions ranged from 0.033 to 0.041 mm/y and was classified as moderate. Under dynamic conditions, the corrosion rate increased to 4.7–5.0 mm/y under stratified smooth flow and 6.2–8.3 mm/y under slug flow, both classified as severe. The higher corrosion rate under slug flow indicates that stronger hydrodynamic conditions were associated with increased corrosion in the tested system. Photometric results agreed with weight-loss results within ±10% for 80% of static, 57% of stratified smooth, and 64% of slug-flow measurements. Applying weight-loss and photometric methods side by side across three flow conditions offers a practical framework for evaluating total dissolved iron as a complementary corrosion monitoring approach.