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Go to Editorial ManagerThe enormous volume of crude oil that needs to be transported results from the growing demand for petroleum. One of the most practical ways to move crude oil is via pipelines. This paper's primary objective is to examine the effects of sulphur, one of the components of crude oil, on welded pipes (API 5L X60, X46, and X42 pipes as well as ASTM A106 pipes). It also aims to show how sulphur content influences different kinds of pipes separately from the other important components of crude oil. The sulphur content of crude oil is determined using the TR-TCXRF equipment. The corrosion rates of welded pipes in four immersion solutions (Different percentages of sulphur content) were computed using weight loss. The samples' corrosion characteristics were assessed morphologically using an optical microscope (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Petroleum welded pipelines' mechanical qualities and resistance to corrosion are significantly impacted by sulphur; an increase in sulphur concentration resulted in a higher rate of corrosion and a decrease in mechanical properties. Among all the welded pipes utilized in the paper, the API 5L X60 welded pipe had the highest corrosion rate, whereas X46 welded pipe was more corrosion-resistant than X46 and X42 in API 5L-type pipes and ASTM A106 pipe.
This study is focused on the assessment of the effects of Sulphur percentage in submerged arc welded API 5L X60 steel under conditions simulated to crude oil environments on its mechanical properties and microstructure. This involved immersing welded specimens in distilled water containing high (0.3250 ml/4L distilled water) and low (0.25 ml/4L distilled water) Sulphur concentrations for four weeks, while unimmersed samples were used as controls for comparison between the two groups of samples. The related experiments were tensile test, hardness measurements, SEM and EDS analyses and XRD analysis. The most mechanically degraded was the high- Sulphur group (H-group); yield strength of 441 MPa (17% loss) and ultimate tensile strength of 506 MPa (11% loss). For the low-sulfur group (L-group), reductions were more moderate: 467 MPa and 523 MPa, respectively. Weld metal (WM) and HAZ hardness values in the H-group were 203 HB and 208 HB, respectively, while those of the L-group were 208 HB and 214 HB. The H-group created a non-protective mixed layer of acicular iron oxides and iron sulfides (FeS) with respect to the microstructural aspects, whereas the L-group developed a thin protective film of iron oxide free from sulfides. Welding parameters were investigated for their effect on the corrosion rate and mechanical properties.
Pipelines are one of the most convenient and effective ways of transporting petrol over a long distance. The environment applies, beyond extremely high external pressures, low temperatures and intensive corrosive process, the occurrence of defects on the pipe body, which compromises the structural integrity of pipelines leading to catastrophic failures. The main modifications concern the mechanical resistance, toughness at low temperatures weld ability and resistance to embrittlement related to hydrogen. Among mechanical characteristics, the fracture toughness is very important for pipeline steels in design and safe assessment. Aiming to enhance the reliability and operation of complex pipelines system, a study based on the mechanics of the elastoplastic fracture in order to determine better prediction of the fatigue life. The materials tested here are API 5L X42 and X52 micro alloyed steels, as well as to evidence the toughness resistance of these materials. Results indicated that both X42 and X52 steel behave in a similar way and in all cases a slight increase of the transition temperature was found. The characteristic toughness value shows an evident loss in mechanical performances if compared to the uncharged one.