CORROSION BEHAVIOR OF API X52 STEEL IN 1% HCL, H2SO4, AND H3PO4 AFTER DIFFERENT IMMERSION PERIODS OF TIME

ABSTRACT: API X52 steel is a low-carbon microalloyed steel widely used in oil and gas pipelines due to its good mechanical properties, weldability, and moderate corrosion resistance. During maintenance operations such as acid cleaning or pickling, the steel may be exposed to aggressive acidic media including HCl, H₂SO₄, and H₃PO₄. This study investigates the corrosion behavior of API X52 steel in 1 wt.% solutions of these acids at different immersion times (24, 48, 120, 144, and 168 h) using weight loss measurements. The results show that corrosion strongly depends on both the acid type and exposure time. After 168 h, the corrosion rates reached 10.07 mm.year⁻¹ in HCl, 7.30 mm.year⁻¹ in H₂SO₄, and 1.78 mm.year⁻¹ in H₃PO₄. The most severe surface degradation occurred in HCl, followed by H₂SO₄, while H₃PO₄ exhibited the lowest corrosion rate due to the formation of a partially protective phosphate layer.