Corrosion of mild Steel and inhibition of Two Field-used Inhibitors in the presence of Elemental Sulfur

摘要

Elemental sulfur deposition is a major concern in sour gas production fields. The direct contact of wet elemental sulfur with mild steel can cause catastrophic corrosion problems. The objective of this project is to study elemental sulfur corrosion and the mitigation of two field used inhibitors to elemental sulfur corrosion. Corrosion, galvanic corrosion and inhibition of two field-used inhibitors for L360MCS mild steel in 3.5 wt% NaCl solution in the presence of elemental sulfur was studied in the laboratory to simulate the condition of a natural gas gathering line. The results indicate that elemental sulfur can cause severe general corrosion and pitting corrosion in 3.5 wt% NaCl solution, and the general corrosion was increased by about 50 times. The corrosion behavior between the metal surface totally covered with elemental sulfur and the metal surface not directly contacted with elemental sulfur was different, a corrosion potential difference of 60-150 mV was observed, which indicates that the deposition of elemental sulfur in the gathering line can cause galvanic corrosion. The corrosion of L360MCS mild steel in the presence of elemental sulfur was inhibited by the batch inhibitor alone, and possibly controlled to an acceptable level with the right concentration and combination of batch and continuous inhibition.