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Hydrogen-induced cracking (HIC) tests were performed on fourteen types of X65 line pipe steels in various environments in which the hydrogen sulfide (H2S) partial pressures (PH2S) were in the range from 1 × 10/5 MPa to 0.1 MPa and pH was in the range from 2 to 5. The conditions governing HIC occurrence were investigated and the following results were obtained: —Hydrogen permeability in steel ([PerFe]) was formulated as a function of PH2S and pH ([PerFe]) = 7.1 + 0.96 × (1.4logPH2S − 0.51 pH), where 0.1 MPa ≥ PH2S ≥ 1 × 10−3 MPa and 5 ≥ pH; [PerFe] = 3.3 + 0.75 × (0.3logPH2S − 0.51 pH), where 1 × 10−3 MPa > PH2S ≥ 1 × 10−5 MPa and 5 ≥ pH. —Critical hydrogen permeability in steel ([Percrit]) was expressed as a function of the critical length of inclusions (acrit) and the maximum hardness of the center-segregation zone (Hvmax) for the investigated thermomechanical-controlled process (TMCP) steels and the controlled rolled and air-cooled (CR) steels (log [Percrit] = [1.7 − 0.0030 Hv] − 1/4log[acrit])...

Passivity of corrosion-resistant alloys (CRA) in chloride (Cl−) + hydrogen sulfide (H2S) environments was investigated electrochemically to clarify the role of alloying elements. Pitting potential (V′c) was correlated with alloying elements of Ni, Cr, and Mo. Ni was shown ineffective in improving pitting resistance in Cl− environments. Passivity in Cl− + H2S environments was discussed based upon Auger electron spectroscopy (AES) analysis, and the roles of each alloying element were clarified.

The critical stress for initiation of stress corrosion cracking (SCC) of a duplex stainless steel (DSS) in a sour environment was investigated using three stress application techniques: co...

The corrosion behavior of corrosion-resistant alloys (CRA) in sour environments was investigated using a duplex stainless steel as a representative CRA. Changes in corrosion morphologies r...

Effects of fluid flow on the corrosion resistance of oil well materials in environments containing CO2 were studied using two experimental techniques. One method utilized weight loss measurements and a large flow loop that could attain a maximum liquid flow rate of 20 m/s. The other utilized electrochemical measurements with rotating electrodes. The corrosion rate of carbon steel measured in the flow loop increased with the flow rate. But, the corrosion rate of 13Cr martensitic stainless steel (UNS S42000) increased to 0.5 mm/y to become constant at the flow rate of 3 m/s. Corrosion rates were obtained from the electrochemical data using the Stern-Geary method, as a function of the speed of rotation. The results obtained by the two experimental methods were compared by hydrodynamic analysis. Using the similarity solutions obtained for mass transfer with pipe flow and the rotating electrode, the rotating velocity was converted to the equivalent velocity in the pipe. On that basis, the corrosion ra...

Crevice corrosion of corrosion-resistant alloys (CRAs) was studied. The crevice pH effect on initiation was investigated with the results of the linear relation between electric charge and...

The initiation and propagation of stress corrosion cracking (SCC) of high alloys in sour gas environments were investigated mainly from the viewpoint of cathodic reactions. The most probab...

This investigation is concerned with the effect of chromium and molybdenum on the formation of the passive film of stainless steels, and its corrosion resistance to the chloride ion. The corrosion resistance to the chloride ion was estimated by the potential decay method and the measurement of the anodic polarization curve. The composition analysis of the passive film was performed by Auger Electron Spectroscopic Analysis. The following conclusions were obtained from the test results: (1) The passive film was more resistant in the environment containing chloride ions as the chromium content in the passive film increased, and (2) molybdenum was observed on AES analysis to have an effect on the increment of the chromium content in the passive film and to promote the passive film formation of stainless steels, probably adsorbing on the active metal surface in the form of molybdate.