Research on the Influence of Insulation Layer Materials on the Corrosion Behavior of Q235 Steel in Heating Pipelines

The surface insulation layers of heating pipelines have an important effect on water vapor penetration and corrosive ion diffusion，ultimately affecting the corrosion behavior of heating pipelines.In this study， the corrosion behavior of Q235 steel thermal pipelines insulated with different materials， including polyurethane and two types of commercially available aerogels made from foam glass， was investigated.Results showed that the wetting angle of foam glass was about 43.8°，which was less than that of the polyurethane and aerogel insulation layers (180°)，making the surface easier to soak in water.Under periodic immersion conditions， the corrosion rate of Q235 steel covered by foam glass was the fastest [about 153.1 mg/(dm2·d)]， significantly higher than that of the samples covered by polyurethane [124.3 mg/(dm2·d)].The corrosion rate of the samples covered by two kinds of aerogel was the lowest [96.73，109.43 mg/(dm2·d)] after the periodic immersion test.There were more pits observed after rust removal in the samples covered by foam glass， indicating the most serious corrosion.The main corrosion product was Fe3O4， which contained a small amount of Fe(OH)(SO4)(H2O)5 and FeCl2(OH)4.