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This paper aims to investigate the influence of temperature (25-65°C) on the adsorption and the inhibition efficiency of gum arabic (GA) for the corrosion of API 5L X42 pipeline steel in 1M HCl.

Inhibition behaviour on steel in HCl has been studied in relation to the concentration of the inhibitor and the temperature using potentiodynamic polarization curves and electrochemical impedance spectroscopy. Thermodynamic parameters of adsorption were calculated from the viewpoint of adsorption theory.

The results show that at a temperature range from 25 to 65°C, GA was a good inhibitor for API 5L X42 pipeline steel, and its inhibition efficiency was significantly stable. The maximum inhibition efficiency (93 per cent) is obtained at 4 g L⁻¹. In absence and presence of GA, there is almost no change in the corrosion mechanism regardless of the temperature. The adsorption of GA on steel surface is an exothermic process. The adsorption of GA involves physical adsorption.

The use of GA as an eco-friendly corrosion inhibitor is practical for carbon steel in HCl.

The stability of inhibition efficiency of GA at a temperature range from 25 to 65°C could find possible applications in acid pickling, industrial acid cleaning and acid descaling.

The purpose of this paper is to investigate the fracture of grade X42 microalloyed steel used as pipe material after tensile test at room temperature and impact tests at 0, −20 and −40°C, respectively.

In the first stage of the study, X42 steels in the form of sheet and pipe materials were selected and etched samples were characterized using light microscope. In the second stage, mechanical properties of steels were obtained by microhardness measurements, static tensile and impact tests and all the broken surfaces were examined by scanning electron microscope to determine the fracture type as a function of both microstructure and loading.

The examinations revealed that: first, the sheet material had a typical ferritic-pearlitic matrix, second, the transverse section of the sheet steel exhibited a matrix consisting of polygonal ferrite-aligned pearlite colonies and the longitudinal one had elongated ferrite phase and pearlite colonies in the direction of rolling, third, ferrite and pearlite distribution was different from the sheet material due to multiaxial deformation in the pipe material, fourth, tensile fracture surfaces of the steels had typical dimple fracture induced by microvoid coalescence, fifth, impact fracture surfaces of the steels changed as a function of the test temperature and cleavage fracture mode of ferritic-pearlitic matrix became more dominant as the temperature decreased, and sixth, grain morphology had an effect on the fracture behavior of the steels.

The paper explains the fracture behaviour of X42 microalloyed pipeline steel and its fractographical analysis.

The key purpose of conducting this review is to identify the issues that affect the structural integrity of pipeline structures. Heat affected zone (HAZ) has been identified as the weak zone in pipeline welds which is prone to have immature failures

In the present work, literature review is conducted on key issues related to the structural integrity of pipeline steel welds. Mechanical and microstructural transformations that take place during welding have been systematically reviewed in the present review paper.

Key findings of the present review underline the role of brittle microstructure phases, and hard secondary particles present in the matrix are responsible for intergranular and intragranular cracks.

The research limitations of the present review are new material characterization techniques that are not available in developing countries.

The practical limitations are new test methodologies and associated cost.

The fracture of pipelines significantly affects the surrounding ecology. The continuous spillage of oil pollutes the land and water of the surroundings.

The present review contains recent and past studies conducted on welded pipeline steel structures. The systematic analysis of studies conducted so far highlights various bottlenecks of the welding methods.

The aim of this study is to assess the opportunity for the development of hydrocarbon transportation using high-strength steel (HSS) in pipeline construction in terms of cost savings and reliability.

Several optimizations of pipeline design and operations were performed to estimate the total life-cycle cost variation associated with different grades of high-strength steel. The generalized reduced gradient (GRG) method was used in an Excel table to determine optimal total life cycle each pipeline. Variables used in this optimization with respect to each steel grade were as follows: pipeline external diameter, wall thickness, number of compression stations and installed power in each compression station. The reliability of a pipeline with optimal cost was assessed to highlight the impact of steel grade on pipeline reliability.

The study showed that the cost reduction is strongly dependent on the adopted gas pipeline configuration. The number of compression stations and external diameter are the main factors influencing the pipeline total life cycle cost, while the steel price seems to have a minor effect, the reduction of the gas pipeline total life cycle does not exceed 5% even with a 50% difference in pipe steel prices between X70 and X100 steels. On the other side, for the same external diameter, X100 steel presents better pipeline reliability against carbonic corrosion compared to X70 steel.

The main contribution of this study is to provide a decision-support tool to help pipeline constructors enhance the profitability of natural gas transmission pipelines. The optimization method used is simple to use for design engineers during a feasibility study.

The present study presents one step to fill the gap concerning the question of balancing the trade-off between cost savings and structural reliability in high-strength steel pipelines during the early stages of feasibility studies. The optimal design and operations parameters ensuring cost savings on total life cycle costs are identified via an optimization method. The impact of selected optimal parameters on the long-term pipeline service life was estimated via a structural reliability analysis.

This paper aims to investigate the reason for natural gas leakage from transmission pipelines between Linyi and Shouguang in China during sealing tests, explore the failure mechanism and provide a reference for taking reasonable measures to prevent such accidents.

Failure analysis for the steel pipe has been addressed with different methods, such as microstructure analysis, inclusion analysis, corrosion product analysis, macro- and micro-morphology analyses and bacterially catalyzed experiments.

Several bulges were observed, especially at the bottom of the steel pipe sample, with the distribution and positioning not related to the weld. The inner surface of the steel pipe was severely corroded, and the oxide scale was flaking in many places. The greatest corrosion area was identified at the bottom of the steel pipe near the gas leakage point. Severe pitting and perforation corrosion in the pipeline were observed, and the main corrosion reaction products were Fe3O4, FeO and FeS. The grain orientation distribution near the crack (coarse grains <101> and fine grains <111> at the microcrack tip) indicates that fine grains may be beneficial in hindering crack propagation.

The principal mechanism for the corrosion failure is supposed to be due to the interaction of chloride ions with the sulfate-reducing microorganisms present and the stress corrosion cracking by chloride and sulfide formed by the sulfate-reducing microorganisms.