Corrosion Behavior of Carbon Steel and 321 Stainless Steel in Naphthenic Acid at High Temperature

Naphthenic acid corrosion is a main corrosion problem in processing of crude oil with high acid values,and the temperature and concentration of naphthenic acid may have great effect on the corrosion.A dynamic high pressure reactor was used to investigate the corrosion behavior of 20＃ carbon steel and 321stainless steel(SS) under the condition of different temperatures and different concentrations of naphthenic acid.The results showed that the corrosion rate of the two materials had a maximum at a certain temperature.When concentration of the naphthenic acid was 5%,the corrosion rate of carbon steel reached the maximum at 280 ℃,and the corrosion rate of 321SS reached the maximum at the range of 260~280 ℃.At 280 ℃,the corrosion rate of the two materials increased sharply with increasing the concentration of naphthenic acid,but the speedup factors were different.The corrosion rate of the two materials in naphthenic acid had a leap range at certain concentration,for carbon steel,the concentration range was between 1.5% to 2%,for 321SS,it was between 3% to 5%.