Sulfide Corrosion Cracking of Linepipe for Sour Gas Service

Abstract

pipe flow; determined indirectly by Well inger and Vetz for particles suspended in air.Assuming a value of 10° for a and K 1 m/s, the value of V at which erosion would commence is 5.8 m/s. At 20° and 30°, erosion would commence at 3 m/s and 2 m/s, respectively. Given these values, it is reasonable to suggest that a small amount of surface roughening produced by corrosion would substantially increase the angle of impact and increase the rate of metal loss by erosion. Conversely, the elimination or reduction of the corrosion component could greatly reduce the erosion losses. These suggestions are borne out by the results of the present study. Conclusions1. Surface roughening due to corrosion increases the local angle of impact of use slurry particles and hence greatly increases the erosion rate; in slurry pipelines carrying sand slurries. Hence, an inhibitor-induced reduction in the corrosion rate also reduces the erosion due to the resulting smoother surfaces.2. The bulk of the metal loss in the absence of inhibitors is due to the straight mechanical erosion of the corrosion roughened surfaces. AbstractSulfide corrosion cracking of linepipe steel was studied from metallurgical and environmental standpoints using laboratory and full size tests. Sulfide corrosion cracking can be classified into hydrogen induced cracking (HIC) and sulfide stress cracking (SSC). HIC initiates at an elongated inclusion and tends to propagate along microstructural inhomogeneity. The addition of copper was effective in preventing HIC in a relatively mild BP solution, due to the formation of a protective film, but was ineffective in a NACE solution. Calcium treatment of desulfurized steel was effective in preventing HIC initiation. Optimization of the manganese content for controlled rolled plate, and the quenching and tempering process were effective in controlling HIC propagation in a NACE solution.SSC in linepipe steel was closely related with HIC. Measures for HIC were also effective in increasing SSC resistance. Girth welded joints were the most susceptible since SSC occurred at the hardest point in the heat affected zone of the final welding pass. Critical hardness for SSC under the stress level of 1.3 times the yield deflection was Hy 250 and 280 for 1.0 and 0.1 atm partial pressure of H 2 S gas, respectively. In a full size HIC test simulating an actual pipeline, HIC developed only in the inner side of the steel, resulting in a decrease of the average crack length by one half as compared with laboratory test results. The residual tensile stress of 50 kg/mm 2 due to girth welding did not introduce any SSC by itself. addition of copper (Cu) prevents HIC because of the formation of protective film." The chemical compositions of the recent steel Abstract Corrosion behavior of for steel has been studied in both stagnant and deaerated solutions containing NaCI concentrations of 200, 1000, and 5000 ppm and sodium nitrite concentrations of 10 -3 N, 10 -1 N, and 1N, respectively. The samples did not show corrosion in the presence of 10 -1 ...

Investigation of hydrogen sulfide stress corrosion cracking of PH 13-8 Mo stainless steel

“…Consequently, the more reverted austenite in the over-aged specimen the less susceptible to hydrogen embrittlement would be the result. Alternatively, the accumulation of hydrogen at the interfaces between matrix and inclusions led to interfacial separations, resulting in an increased susceptibility of the alloy [23][24][25].…”

The effect of hydrogen induced cracking on the integrity of steel components

“…Very few studies have been conducted to investigate the effect of welding residual stresses on the occurrence of SWC. The study of Taira et al (1979) seems to suggest that there is no effect of residual stresses.…”

Sulphide stress corrosion cracking of multiple welding repairs of girth welds in line pipe

“…1,2,10-15 The ICHAZ is characterised by heating between Ac 1 -Ac 3 transformation temperature (azc region) by the thermal cycles of welding, enhancing the formation of martensite-austenite microconstituents and for the minimum hardness (low yield strength). According to the results of Taira, 5 Endo, 10 Kobayashi 11 and Nippon Kokan, 15 the yield strength of the ICHAZ decreases 10% of the original yield strength, and in addition, the s th /s y ratios for the welds are usually smaller by y10% of the yield strength of the BM. That is, this decrease in strength allows microscopically the ICHAZ to be deformed plastically to the larger extent, which may lead to a high possibility of developing SSC in the ICHAZ.…”