In this study, failure pressure prediction was conducted in a pipeline with localized corrosion in base metal (BM), heat-affected zone (HAZ), and welding bead (WB) by finite element (FE) analysis. In the gas pipeline industry, there are methods (B31G, RESTRENGH, Shell, DNV, PCORR, and Fitnet FFS) and authors' approaches (Choi and Cronin) to determine the failure pressure. However, one disadvantage of these methods is that their equations do not consider damage corrosion at the HAZ or WB. They consider corrosion only in the BM. The corrosion shape is rectangular with a radius at the edges. In this study, the corrosion defect depth (d) was varied. The corrosion defect length (L) and the corrosion defect width (W) were equal. A type of rectangular corrosion defect with a radius at the edges in the longitudinal and circumferential directions was proposed. True stress–strain curves for BM, HAZ, and WB of an API 5 L X52 were introduced in the FE program. The results show that the pressure decreases as d, L, and W increase. This is because the damage corrosion is more severe as it grows, which causes the failure pressure to decrease.

This study presents K_IC data obtained from K_IC-CVN correlations from Charpy CVN values. For this study, T-welded connections were manufactured from ASTM A36 and E6013 electrodes in dry conditions. Then, a rectangular grinding at the weld toe was carried out and filled with wet welding. Charpy specimens were extracted to obtain CVN values. An exhaustive search through the literature of several authors was performed to collect experimental CVN data about wet welding being applied to A36 steel for comparison with CVN data obtained in this study. By using Charpy impact energy (CVN), K_IC values could be predicted by K_IC-CVN correlations. In addition, correlations were presented to obtain K_IC values in the lower shelf, transition temperature zones and different zones for the energy-temperature curve of A36 steel. Of these correlations, Barsom’s equation was adopted, because he applied the stress yield (σ_YS) of the material and it can be applied in all zones for the energy-temperature curve. The results revealed that CVN values are proportionate to K_IC, this data decreases as water depth increases. This took place because several discontinuities, such as, porosity, slag inclusion, non-metallic inclusion, cracking and microstructures are present in the wet welding.

It is well known that the mechanical properties of a steel plate depend on the anisotropy of the material and the rolling directions. This paper presents the results of the Charpy V-Notch (CVN) impact test for the ST, TL, TS, LS, LT, 45°, and SL directions in API 5L X52 pipelines with electric-resistance-welded (ERW) and seamless (SMLS) pipes. Charpy specimens were manufactured and tested according to the ASTM E23 standard in laboratory conditions. All possible directions in the pipe were tested. Three Charpy specimens were tested for each direction, for a total of 21 Charpy tests. Moreover, the microstructures, hardness, ductile and brittle areas, and fracture surfaces of the Charpy specimens are presented in this research. The results show that the Charpy energy values, hardness, and microstructures depend on the direction of the specimens. The Charpy values of the SMLS pipe are higher than those of the ERW pipe because of several metallurgical factors, such as grain size, non-metallic inclusions, delaminations, and microstructures.

This work shows the effect of artificial aging on the mechanical properties of an API 5L Gr. B steel that undergoes different artificial aging times (0, 500, 1250, and 1500 h). Among the mechanical properties studied are the stress–strain curve, yield stress, and ultimate tensile stress. In addition, the parameters from the Ludwik–Hollomon equation, which are the parameter (K) and the work-hardening coefficient (n), are obtained for the true stress–strain curve. Once the true stress–strain curve is plotted, a 3D model of a transverse crack in a pipeline is proposed. The crack defects are straight, and the finite element method (FEM) is used to determine its behavior at different sizes in order to estimate the failure pressure. It can be said that the mechanical properties (stress–strain curve) increase for an aging time of 500 h compared to the air condition because of the over-aging process, something that is well recognized in the literature. In general, past the over-aging condition, with an increase in the aging time, the mechanical properties tend to decrease. This behavior is similar for the failure pressure. The FEM is sensitive to the decrease in mechanical properties along with the true stress–strain curve.

Pt–Mo nanoparticles supported by MWCNT were synthesized by wet impregnation and applied to desulfurize extra-heavy crude oil. Structural, morphological, and chemical characterizations confirmed uniform dispersion of Pt and Mo on MWCNT surfaces. The Pt–Mo nanoparticles had crystallite sizes ranging from 1.7 to 28 nm. The catalysts were used in the aquathermolysis of UTSIL crude oil, showing good stability and activity. Sulfur was reduced by 50% at 50°C and 80% at 100°C. FT-IR spectroscopy revealed the formation of hydrogenated aromatic rings and a decrease in sulfonic groups during desulfurization. Graphical abstract