Investigating the influence of temperature on the selection of criteria for evaluating the propensity of tube steels to corrosion cracking at low loading speeds

The paper studies how temperature within the range of 20-80°C influences the destruction of tube steels in environments containing hydrogen sulfide and carbon dioxide. The tensile tests diagrams of tube steels with increasing temperature in hydrogen sulfide and carbon dioxide are analyzed. It is shown that increasing temperature affects the tendency of tube steels towards corrosion cracking. The criterion for evaluating the tendency towards corrosion cracking at increasing temperature does not change qualitatively and represents stress and relative deformation observed when a specimen is destroyed.

Oxidation Behaviour of Welded ASTM-SA210 GrA1 Boiler Tube Steels under Cyclic Conditions at 900°C in Air

ASTM-SA210-Grade A1 boiler tube steels were welded by shielded metal arc welding (SMAW) and tungsten inert gas processes. The oxidation behaviour of the welded steels was evaluated under cyclic conditions at 900°C. Visual observations and thermogravimetric data were measured at the end of each cycle. Finally, the scale was analysed using X-ray Diffraction, Scanning-Electron Microscopy/Energy-Dispersive X-Ray studies. A SEM Back scattered image analysis of the cross-section of the oxide scale thickness has been made to measure the oxide scales formed over the welded steels. SMAW welded steel showed the more oxidation rate (in terms of weight gain) as compared to TIG welded at the test temperature of 900°C and it was due to the formation of more cracks in oxide scale, and a thick oxide scale was found on HAZ and weld region.

Structural heterogeneities of tube steels taken into account in the development of contactless magnetometry of pipeline systems

One of the problems facing gas and oil pumping companies is the aging of pipelines, whose service life is rapidly approaching, or even exceeding, the resource planned during design. The only possible way to evaluate the possibility of further safe operation and residual life of pipelines is to conduct studies of the actual state of the parent metal and welded pipe joints. However, the direct investigation of metal pipes is practically impossible due to the linear dimensions of objects and their position. The analysis of the state of the pipeline system can only be made with the help of contactless, most often magnetic methods. Interpretation of magnetograms and detection of defects that are dangerous for the operation of pipes is one of the most difficult problems facing defectoscopists, which can be solved only by creating a library of structures and defects. This paper presents the results of a structural analysis of the metal of pipes, which must be taken into account when interpreting the results of magnetograms. These results constitute a part of the library of defects in pipeline systems developed in SPbPU.

Effect of CO2 Partial Pressure on CO2/H2S Corrosion of Oil Tube Steels

The CO2/H2S corrosion behaviors of oil tube steels N80 and P110 at different CO2 partial pressure (45psi, 135psi, 225psi, 315psi) were investigated by corrosion tests, corrosion rate calculation and corrosion morphology observation. The results show that at different CO2 partial pressure, super-serious CO2/H2S corrosion occurs on steel N80 and steel P110. With the increase of CO2 partial pressure, the CO2/H2S corrosion rates of both steels increase gradually.

Effect of Temperature on CO2/H2S Corrosion of Oil Tube Steels

The CO2/H2S corrosion behaviors of oil tube steels N80 and P110 at different temperature were investigated by corrosion rate calculation and corrosion morphology observation. The results show that with the increase of temperature, the CO2/H2S corrosion rates of both steels increase at first and then decrease, and reach the peak at 90°C. The corrosion rate of steel P110 is higher than that of steel N80.