Analysis of Oxide Scales Formed in the Naphthenic Acid Corrosion of Carbon Steel

Abstract Corrosion rate data are presented for low carbon steel in (1) a combination of sulfur dioxide, water vapor and air, and (2) aqueous solutions of sulfurous acid in the absence of air, at ordinary temperature. Information as to the nature of the corrosion products is presented and it is shown that this depends on the place in which the corrosion takes place to an important extent.

Download Full-text

Predicting Sulfidic and Naphthenic Acid Corrosion

CORROSION ◽

10.5006/1.3319109 ◽

2009 ◽

Vol 65 (12) ◽

pp. 831-844 ◽

Cited By ~ 12

Author(s):

J. Hau

Keyword(s):

Shear Stress ◽

Exposure Time ◽

Acid Corrosion ◽

Naphthenic Acid ◽

Naphthenic Acids ◽

Sulfur Compounds ◽

Velocity Shear ◽

Threshold Behavior ◽

Temperature Range ◽

Si Content

Abstract This paper reviews the factors that are hindering the development of models to predict corrosion due to sulfur compounds, naphthenic acids, or both, acting simultaneously on steels within the temperature range typically from 230°C to 400°C. These factors are identified as data scattering that do not distribute normally, variables or factors that do not exert their influence in a gradual manner but as a threshold behavior, and the interactions between the factors of sulfidic and naphthenic acid corrosion; exposure time, temperature, and velocity (shear stress); and the chromium and molybdenum content of the steels (Si content is not discussed). Not dealing with the interactions is probably the largest obstacle, followed by data scattering.

Download Full-text

The effect of volatile organic acids and CO2 on the corrosion rate of carbon steel from a Top-of-Line-Corrosion (TLC) perspective

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1201/1/012079 ◽

2021 ◽

Vol 1201 (1) ◽

pp. 012079

Author(s):

S B Gjertsen ◽

A Palencsar ◽

M Seiersten ◽

T H Hemmingsen

Keyword(s):

Carbon Steel ◽

Corrosion Rate ◽

Organic Acid ◽

Carbonic Acid ◽

Acid Corrosion ◽

Iron Concentration ◽

Critical Factor ◽

Steel Corrosion ◽

Carbon Steels ◽

Corrosion Rates

Abstract Models for predicting top-of-line corrosion (TLC) rates on carbon steels are important tools for cost-effectively designing and operating natural gas transportation pipelines. The work presented in this paper is aimed to investigate how the corrosion rates on carbon steel is affected by acids typically present in the transported pipeline fluids. This investigation may contribute to the development of improved models. In a series of experiments, the corrosion rate differences for pure CO2 (carbonic acid) corrosion and pure organic acid corrosion (acetic acid and formic acid) on X65 carbon steel were investigated at starting pH values; 4.5, 5.3, or 6.3. The experiments were conducted in deaerated low-salinity aqueous solutions at atmospheric pressure and temperature of 65 °C. The corrosion rates were evaluated from linear polarization resistance data as well as mass loss and released iron concentration. A correlation between lower pH values and increased corrosion rates was found for the organic acid experiments. However, the pH was not the most critical factor for the rates of carbon steel corrosion in these experiments. The experimental results showed that the type of acid species involved and the concentration of the undissociated acid in the solution influenced the corrosion rates considerably.

Download Full-text

Corrosion inhibition of some azole derivatives on carbon steel in hydrochloric acid solution

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-05-2013-1266 ◽

2014 ◽

Vol 61 (5) ◽

pp. 300-306 ◽

Cited By ~ 6

Author(s):

B.P. Markhali ◽

R. Naderi ◽

M. Sayebani ◽

M. Mahdavian

Keyword(s):

Carbon Steel ◽

Hydrochloric Acid ◽

Organic Compounds ◽

Corrosion Inhibitors ◽

Inhibition Efficiency ◽

Electrochemical Impedance ◽

Acid Corrosion ◽

Molecular Structures ◽

Inhibition Mechanism ◽

Content Type

Purpose – The purpose of this paper is investigate the inhibition efficiency of three similar bi-cyclic organic compounds, namely, benzimidazole (BI), benzotriazole (BTAH) and benzothiazole (BTH) on carbon steel in 1 M hydrochloric acid (HCl) solution. Organic inhibitors are widely used to protect metals in acidic media. Among abundant suggestions for acid corrosion inhibitors, azole compounds have gained attention. Design/methodology/approach – The inhibition efficiency of the three organic compounds was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Findings – Superiorities of BTH and BTAH corrosion inhibitors were shown by EIS data and polarization curves. Moreover, the results revealed that BTAH and BTH can function as effective mixed-type adsorptive inhibitors, whereas no inhibition behavior was observed for BI. Both BTAH and BTH obeyed Longmuir adsorption isotherm. The results obtained from this isotherm showed that both inhibitors adsorbed on the specimen surface physically and chemically. The difference in inhibition efficiencies of BTAH, BTH and BI was related to the presence of nitrogen and sulfur hetero atoms on their molecular structures. Originality/value – This study evaluated inhibition efficiency of BI, BTAH and BTH using electrochemical methods. In addition, the study attempted to find inhibition mechanism of the inhibitors and to find modes of adsorption of the inhibitors, correlating effects of heteroatoms and inhibition efficiency.

Download Full-text