Effects of Gathering and Transportation Condition on H2S-CO2 Corrosion Behavior of X65 Steel Pipeline
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Graphical Abstract
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Abstract
The indoor corrosion simulation experiment was used to study the influence of different gathering and transportation conditions (gathering temperature, pipeline operating pressure, , Ca2+, Mg2+, Cl- content and pH) on H2S-CO2 corrosion behavior of X65 steel pipeline in a sulfur-containing gas field during its daily production and transmission. The results show that with the increase of temperature and pressure, the corrosion rate gradually increased, and operating pressure had the most significant effect on it. As Ca2+, Mg2+, content and pH increased, the density of corrosion products increased, and the corrosion rate gradually decreased. As the Cl- content increased, the tendency of localized corrosion increased, uniform corrosion rate soared up at first and then droped, peaking when Cl- concentation was 10 g/L. In a certain range, pH could response to H2S-CO2 corrosion rate in gathering pipelines, but it was difficult to reasonably evaluate the corrosion severity by only considering the pH. Under experimental conditions, H2S-CO2 corrosion products were mainly composed of Maginot ore and magnetic pyrite. The surface of the sample formed a longitudinal multi-region electro couple. Furthermore, the effects of the micro-zone electro couple and the occlusion battery led to the occurrence and development of localized corrosion.
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