Corrosion Metal Loss Research Articles

Numerical analysis of the brittle strength of welded pipelines with corrosion metal loss in the transportation of blends of natural gas with hydrogen

Numerical analysis of the brittle strength of welded pipelines with corrosion metal loss in the transportation of blends of natural gas with hydrogen

ИССЛЕДОВАНИЕ КОРРОЗИОННОЙ СТОЙКОСТИ АУСТЕНИТНЫХ СТАЛЕЙ, НЕ ЛЕГИРОВАННЫХ И ЛЕГИРОВАННЫХ АЗОТОМ В ОКИСЛИТЕЛЬНОЙ И ХЛОРИДНОЙ СРЕДАХ

The corrosion resistance of the developed austenitic steel 03Cr20Ni9Mn3N0.30, alloyed with nitrogen in comparison with steel 03Cr18Ni11 (AISI 304L) was studied. The analysis of corrosion resistance to intergranular corrosion in 65 % boiling nitric acid was carried out according to the “DU method” of GOST 6032–2017. The studied steels resistance in 42% boiling MgCl2 solution was also evaluated. It has been established, that the corrosion rate in 65 % boiling nitric acid for steel AISI 304L and nitrogen-alloyed is comparable and amounts to about 0.2-0.4 mm / year. However, it was shown that the incubation period to achieve a sensitization state in steel 03Cr20Ni9Mn3N0.30 is about 4 times longer than of steel AISI 304L. Additionally, the conditions for the studied steels resistance to intergranular corrosion in boiling 65 % nitric acid after heating at temperatures from 500 to 850 °C and holdings from 1 hour to 100 hours are determined. Based on the test results, a Rollason diagram was constructed. The microalloying effect with boron and rare-earth metals on 03Cr20Ni9Mn3N0.30 corrosion resistance (according to the DU method of GOST 6032-2017) was also investigated. The permissible concentrations of microalloying elements (boron up to 0.0025 wt. %, and rare-earth metals up to 0.04 wt. %) are determined, which provide high technological plasticity without reducing its corrosion resistance. When tested by the DU method, the corrosion metal loss in both of these cases was not more than 0.35 mm/year. However, with the boron introduction in an amount of 0.01 wt. %, the corrosion rate increases sharply to 1.328 mm/year, while reducing technological plasticity. As a result of compared steels testing samples for stress corrosion in a 42 % boiling MgCl2 solution. The superiority of 03Cr20Ni9Mn3N0.30 steel over AISI 304L steel at a strain of 280 MPa was more than 8 times higher, and at a strain of 100 MPa almost 10 times higher. It should be noted that the failure nature of steel 03Cr20Ni9Mn3N0.30 and AISI 304L is identical, but the time required for cracks initiation by almost differs.

Relationship Between in-situ Measurement of Soil Parameters and Metal Loss Volume of X70 Carbon Steel Coupon

Corrosion in soil environments is a serious threat to underground metallic structures such as oil and gas pipelines, waste containers and pilings. This study investigates the relationship between in-situ soil parameters and metal loss of X70 carbon steel. A total of 207 carbon steel coupons of X70 were installed underground at five sites for 18 months and have been retrieved every 3 months to measure the metal loss as a function of time. This study focused on in-situ corrosion parameters, namely, soil resistivity (Res), pH, moisture content (Mc) and chloride content (CI). The results of corrosion metal loss and in-situ parameters were analyzed using statistical methods to obtain the relationship of the studied p arameters to metal loss. Extreme data were removed through proper outlier's detection technique: Box plot, Dixon test and t-test. Corrosion test were then carried out to examine the relationship between in-situ measurement of soil parameters and metal loss. The results indicated that Mc, CI and Res were found to be the most influential variables on the observed metal loss. An increase in Mc and CI is likely to promote corrosion growth whereas higher resistivity will reduce the corrosion risk. Nevertheless, pH was found to be relatively insignificant to the corrosion process.

Guidelines for Repair Welding of Pressure Equipment in Refineries and Chemical Plants

This paper outlines the technical logic/steps that have been documented in JWES-CP-0902, “Guidelines for Repair Welding on Pressure Equipment”(hereinafter the Guidelines). The paper covers the work flow logic that can be followed by maintenance personnel as they address making a repair welding in pressure vessels/piping made of both ferrous and nonferrous materials after flaw detection during inspection during refinery operation. Material degradation factors that are considered include: strength loss, ductility loss, temper embrittlement, σ embrittlement, corrosion metal loss, stress corrosion cracking, fatigue, and creep.

The effect of the width to length ratios of corrosion defects on the burst pressures of transmission pipelines

This paper deals with the investigation of the load carrying capacity of transmission steel pipelines in case of occurrence of corrosion defects on the outer surface of the pipe wall. Different including dimensions of the corrosion metal loss (length, width, depth) influence the burst pressure of the corroded pipelines to a different extent. The effects of the width to length ratios of the corrosion defects were investigated with numerical simulations included in this article. The calculations were performed with FEA (Finite Element Analysis) method and the results were verified based on measurement data.

A novel capacitance sensor for fireside corrosion measurement

Fireside corrosion in coal-fired power plants is a leading mechanism for boiler tube failures. Online monitoring of fireside corrosion can provide timely data to plant operators for mitigation implementation. This paper presents a novel sensor concept for measuring metal loss based on electrical capacitance. Laboratory-scale experiments demonstrated the feasibility of design, fabrication, and operation of the sensor. The fabrication of the prototype sensor involved sputtering deposition of a thin metal coating with varying thickness on a ceramic substrate. Corrosion metal loss resulted in a proportional decrease in electrical capacitance of the sensor. Laboratory experiments using a muffle furnace with an oxidation environment demonstrated that low carbon steel coatings on ceramic substrate survived cyclic temperatures over 500 degrees C. Measured corrosion rates of sputtered coating in air had an Arrhenius exponential dependence on temperature, with metal thickness loss ranging from 2.0 nm/h at 200 degrees C to 2.0 microm/h at 400 degrees C. Uncertainty analysis indicated that the overall measurement uncertainty was within 4%. The experimental system showed high signal-to-noise ratio, and the sensor could measure submicrometer metal thickness changes. The laboratory experiments demonstrated that the sensor concept and measurement system are capable of short term, online monitoring of metal loss, indicating the potential for the sensor to be used for fireside corrosion monitoring and other metal loss measurement.

Failure behavior of carbon steel pipe with local wall thinning near orifice

Monotonic four-point bending tests were conducted using pipe specimens having an orifice undergoing local wall thinning. The effects of local wall thinning on the fracture behaviors of pipe were investigated. Local wall thinning was machined on the inside of pipes in order to simulate erosion corrosion metal loss. The configurations of the eroded area were l = 100 mm in axial length, d/ t = 0.5 and 0.8 in thickness ratio, and 2 θ = 180° in angle. The area undergoing local wall thinning was subjected to either tensile or compressive stress. Failure type could be classified into ovalization, local buckling, and crack initiation, depending on thickness ratio, and stress at the eroded area. Three-dimensional elasto-plastic analyses were also carried out using the finite element method, which is able to accurately simulate fracture behaviors. Failure analysis map was constructed for pipes with or without orifice based on the results of finite element analyses in order to investigate the effect of orifice on the failure behaviors.

Corrosion and Magnetite Growth on Carbon Steels in Water at 310 C – Effect of Dissolved Oxygen, pH, and EDTA Addition

Abstract The formation of magnetite at 310 C on carbon steels has been studied at pH 7.0 and 10.5 in presence of two oxygen levels (<0.05 and 3.5 ppm) by kinetics, scanning electron microscopy, and electrochemical measurements. An adherent and protective magnetite of thickness 1.8 μ was observed after 530 hours of exposure at pH 10.5 and oxygen <0.05 ppm. Higher oxygen and neutral pH conditions resulted in only a slight increase in the overall corrosion rates, but the magnetite was still adherent and protective. Two stages in the oxide formation were seen. During the first stage, the oxide growth was nearly parabolic and continued up to a thickness of about 4 microns followed by the second stage under steady state conditions, with a low corrosion rate of 0.015 mm/y or less. The addition of EDTA up to 300 ppm has resulted in improving the adherence of the oxide and decreasing the corrosion metal loss. Room temperature electrochemical measurements have shown that the passivity proceeds in two stages, Fe(OH)...