Corrosion control

This paper presents an updated review of the external corrosion and failure mechanisms of buried natural gas and oil pipelines. Various forms of external corrosion and failure mechanisms such as hydrogen-induced cracking (HIC), hydrogen embrittlement (HE), corrosion fatigue (CF), stress corrosion cracking (SCC) and microbiologically influenced corrosion (MIC) for oil and gas pipelines are thoroughly reviewed. The factors influencing external corrosion and possible forms of environment-assisted cracking (EAC) of pipeline steels in the soil are also reviewed and analyzed in depth. In addition, the existing monitoring tools for the external corrosion assessment and the models for corrosion prevention and prediction, failure occurrence, and remaining life of oil and gas pipelines, are analyzed. Moreover, the articles on external corrosion management, reliability-based models, risk-based models, and integrity assessment including machine learning and fuzzy logic approaches, are also reviewed. The conclusions and recommendations for future research in the prevention and prediction of external corrosion are presented at the end.

Hydrogen evolution and permeation occur during electroplating, corrosion, and cathodic protection. Hydrogen accumulates in areas of high stress and may reach a critical concentration, potentially causing fractures and catastrophic damage. This chapter describes hydrogen permeation and hydrogen-induced damage in metals and alloys. It also discusses hydrogen evolution kinetics, theoretical diffusion solutions, and basic hydrogen permeation models. Models are used as a diagnostic tool to determine the effectiveness of various metals and alloys as hydrogen permeation inhibitors. It then explains experimental atomic hydrogen permeation transient determination and hydrogen absorption rate constants and diffusivity evaluation into metals using case studies. Hydrogen embrittlement, hydrogen-induced cracking, hydrogen blistering, and hydrogen stress cracking are also discussed to show the relationship to hydrogen permeation and hydrogen-induced cracking mechanisms. Finally, various techniques used to prevent and control hydrogen damage of metals and alloys are described.

A series of metal-phosphonate organic-inorganic polymeric hybrid materials are synthesized, structurally characterized, and evaluated for their anticorrosion properties for the protection of carbon steels. These materials are Zn-AMP (where AMP ) amino-tris(methylenephosphonate)), Zn-HDTMP (where HDTMP ) hexamethylenediamine-tetrakis(methylenephosphonate)), and Ca-PBTC (where PBTC ) 2-phosphonobutane-1,2,4-tricarboxylate)). Their structures are described and compared. Their corrosion inhibition performances are also compared, and some interesting conclusions are drawn that relate molecular structure to inhibitory activity.

The constant growth in the area of metal phosphonate materials is exemplified with rich chemistry and a variety of applications. From the multitude of subjects related to metal phosphonates, we have decided to focus on metal phosphonate coordination polymers as corrosion inhibitors in the present Comment. A plethora of metal phosphonate organic-inorganic polymeric hybrid materials have been synthesized, structurally characterized, and evaluated for their anticorrosion properties for the protection of carbon steels. These materials are composed of a metal ion (usually Zn 2þ , Ca 2þ , Sr 2þ , Ba 2þ , etc.) and polyphosphonate ligands such as AMP (amino-tris-(methylenephosphonate) and HDTMP (hexamethylenediaminetetrakis(methylenephosphonate), or carboxyphosphonate ligands, such as PBTC (2-phosphonobutane-1,2,4-tricarboxylate) and HPAA (hydroxyphosphonoacetate). Their corrosion inhibition performance has been evaluated and some interesting conclusions are drawn relating molecular structure to inhibitory activity.

Considering corrosion rate during the remaining life assessment of aging pipelines is fundamental to calculate the interval between two consecutive inspections. A total of 798 internal and external corrosion defects have been detected, using the Magnetic Flux Leakage intelligent inspection tool, over 48 km of a pipeline length located in the west region of Algeria. The statistical analysis has shown that there is a strong correlation between the corrosion defect length and the corrosion defect circumferential width, with a significant correlation coefficient equal to 82.87%. A probabilistic methodology is presented for the assessment of the remaining life of a corroded pipeline transporting gas, and a finite element method (FEM) was used to assess the pipeline failure pressure. The numerical FEM modeling results were compared with the commonly used codes-models for calculating limit pressure to establish a more realistic and accurate engineering model. The reliability analysis of an API 5L X60 steel made Algerian natural gas pipeline, in service for thirty years, and exposed to active corrosion attack, is presented. The sensitivity analysis of the basic random variables within the nonlinear limit state function was carried out to bring out the relative contribution of each variable affecting the remaining life of corroded pipelines. The reliability analysis is carried out by using Breitung's formula, based on the second-order reliability method (SORM). The reliability assessment of the corroded pipeline is based on the usage of the notched failure assessment diagram (NFAD), different codes for the calculation of the failure pressure, and the numerical results using the finite element analyses (FEA) software ANSYS.

The effect of inhibitor concentration and temperature on the corrosion process of copper–nickel alloy in presence of naphthylamine (NA) and phenylenediamine (PDA) in 5% HCl has been investigated by weight loss technique. Maximum value of inhibitor efficiency was 85.6% for NA at 35 °C and 0.085 M inhibitor concentration, while the lower value was 1% at 55 °C and 0.01 M in the presence of PDA. Two mathematical models were used to represent the corrosion rate data: second order polynomial model and exponential model. Non-linear regression analysis shows that the first model was better than the second model with high correlation coefficient.

In this research, the effect of thiosulfate ion on pitting corrosion behavior of 316 stainless steel was studied. Part I of this work deals with the influence of thiosulfate on the critical pitting temperature of 316 SS in 0.1 M chloride solution and studies the effect of this ion on the pit chemistry. Electrochemical experiments performed in absence and presence of 0.01 M thiosulfate ion revealed that thiosulfate deteriorates the CPT. Pencil electrode studies showed that thiosulfate addition decreases both saturation concentration of metal cations necessary to metal salt precipitate at the pit bottom (CS) (the value of diffusion controlled limiting current density (iLim) was decreased) and the ratio of C*/CS (where C* is the critical concentration of metal cations in pit solution essential for a pit to remain stable) while it increases the anodic dissolution rate in a simulated pit solution. Furthermore, scanning electron microscopy showed that the lacy cover formed over the pits mouth has coarser pore structure in the presence of thiosulfate ion.

tThe inhibition of steel–copper couple galvanic corrosion in petroleum waste water solutionby Curcuma longa was studied at different temperature and different cathode to anode ratiosusing weight loss technique. Inhibition efficiency was increased with increase in inhibitorconcentration but decrease with rise in temperature. Adsorption followed the Temkinisotherm with negative values of G◦ads, suggesting a stable, and spontaneous inhibitionprocess. Mathematical equations were suggested to represent the corrosion rate data withhigh correlation coefficients. Quantum chemical parameters were calculated for inhibitor susing the AM1-SCF method to simulate the adsorption of the C. longa molecules on couple surface.

The electrochemistry of a 13% Cr stainless steel (API5CT L80-13Cr) in 3% NaCl containing acetate and either acetic acid or carbon dioxide at 333 K is explored using RDE voltammetry. The reduction of proton, carbonic acid and acetic acid occur simultaneously, immediately negative to the corrosion potential. Acetic acid gives a well formed reduction wave and the current densities increase with the equilibrium concentration of acetic acid in the medium; in the plateau region, the reduction is mass transport controlled. Despite this reduction process, the corrosion resistance and passivation current density are independent of the acetic acid concentration. It is confirmed that the 13% Cr stainless steel is much more resistant to corrosion that X65 carbon steel and, unlike the carbon steel, its rate of corrosion does not vary with acetic acid concentration. The properties of the passivating film appear to dominate the behaviour of the 13% Cr stainless steel.

The corrosion inhibition of copper–nickel alloy by benzotriazole (BTA) in 1.5 M HCl has been
investigated by weight loss and polarization techniques at different temperatures. Maximum value of inhibitor
efficiency was 99.8% at 35°C and 0.1 M inhibitor concentration, while the lower value was 86.3% at 65°C
and 0.02 M inhibitor concentration. The activation energy values were higher in presence of BTA which indi
cate that in presence of inhibitor, corrosion reaction requires more energy to occur. Two mathematical models
were used to represent the weight loss corrosion rate data with high correlation coefficients. Electrochemical
polarization measurements showed that BTA is a mixed type inhibitor.

Syntheses and structures of alkaline earth metal ions and EDTMP, ethylenediamine-tetrakis(methylenephosphonate), are reported. The isostructural Ca 2+ and Sr 2+ analogs have 1D topologies, with EDTMP acting as both chelating and bridging ligand. The M-EDTMP compounds act as Fe-oxide removers from corroded surfaces.

Present work studied the high temperature corrosion inhibition rate of steel in
different concentration ratios of MgO, to corrosive fuel ash in temperature range 600 – 900
o C and time range 10 – 40 h. Weight loss technique was used to evaluate the corrosion rate
values. Corrosive environment was collected locally from boilers of Northern Baghdad
Power Plant Station. Analysis focused on determining optimum mathematical equation and
ANN architecture in order to gain good prediction results. Three mathematical equations
and five ANN architectures were recommended. Computer aided program was used for
developing these models. Results show that polynomial mathematical equation and MPL
are able to perfectly forecast corrosion data with high correlation coefficients.

The corrosion behavior of A106 carbon steel in 30 wt.% piperazine (PZ, a cycling amine) solutions was investigated by potentiodynamic polarization, EIS, LPR, SEM/EDS, and XRD. For comparison, the corrosion was also conducted in the benchmark solvent of monoethanolamine (MEA) solution. Similar to MEA, initial corrosion testing results in PZ solvent showed that the corrosion rate increases with increases either in CO2 loading from 0.23 to 0.43 mol CO2/mol alkalinity (C/N) or in temperature from 20 to 80 oC. Short term corrosion investigations showed an approximately two orders of magnitude lower corrosion rate for A106 in 0.43 C/N CO2 loaded 30 wt.% PZ at 80 oC than in the same conditions but with 30 wt.% MEA. The difference was due to the ability to form a dense and protective FeCO3 layer on the metal surface in PZ as opposed to in MEA solutions. Possible mechanisms are discussed.

Fossil fuels are not renewable energy in addition they create massive pollution in the environment. This pollution affects air, water and the food. Because of global fossil fuel shortage and environmental pollution, solar energy utilization has developed rapidly. Solar energy is considered the energy supplied by the sun that is a renewable and clean energy. This review investigates corrosion of silver, corrosion of solar cells and ways of control corrosion process of solar cell.

Corrosion combined with fouling growth can interfere with the operation of submerged equipment, impose increased loading stresses and accelerate deterioration of marine structures, and adversely affect the performance of ships by increasing hydrodynamic drag, which necessitates the use of more power and fuel to move the ship through the water. The protection of the submerged portions of a ship's hull seems to have been long acknowledged and practiced but corrosion related failure of ship components continue to occur giving economical loss to ship owners. An enlightened approach to materials selection, protection and corrosion control is needed to minimize the risk of failures or major renewals of hull structures during the ship's expected life span. Further, Proper and cost effective corrosion protection measures are necessary to maintain the asset value of the vessel with a special emphasis on the means and methods now being adopted in international regulatory regimes to contain it. This paper addresses the causes of corrosion in ship and the way in which corrosion can be reduced or entirely eliminated in a ship by integrating both technical and non technical methods of corrosion control.

Brine purification process of GHCL did not meet the specification of electrolyzer in the context of excess hydroxide ion (OH-). The electrolyzer, anolyte tank and dechlorination tower tank faced serious corrosion. This paper describes an innovative method adopted to meet the electrolyzer's specification of excess OH-. This method consists of an innovative HCl dosing system added to purified brine tank. After adopting this method corrosion of electrolyzer, anolyte tank and dechlorination tower tank has been decreased in a noticeable rate. Also some chemical dosings have been reduced.

The purpose of this paper is to evaluate the electrochemical kinetics parameters of galvanic corrosion inhibition of the
copper alloy- steel alloy couple, exposed to cooling tower water. Polyvinyl alcohol was utilized to evaluate the inhibition
behaviour under galvanic couple conditions. Polarization technique was used to evaluate the corrosion rate data. Barnartt`s
three point method and McLaughlin method were used to evaluate the kinetics parameters. The results were compared with
the results of conventional Tafel extrapolation method.

An Inconel 601 crucible containing a ternary eutectic mixture of lithium carbonate (Li 2 CO 3), potassium carbonate (K 2 CO 3) and sodium carbonate (Na 2 CO 3) was placed into a 450˚C preheated furnace to check their compatibility as storage and containment materials for Thermal Energy Storage (TES) applications. Failure was observed after around 22 hours and proved to be assisted by the diffusion of oxygen and carbide forming elements through grain boundaries. Microstructural studies showed cracks of an intergranular type resulted from the high amount of residual stress and microstructural evolution during the thermal exposure; EBSD investigations confirmed the occurrence of partial recovery leading to stress reduction in the matrix. The failure of this nickel-based superalloy crucible was concluded to be a combination of stress induced by sensitization, exposure to hot corrosive media, and cold work manufacturing besides thermal instability of the microstructure.

In this work we have developed a decision support system that can determine corrosion and project the time for corrosion growth maintenance using probabilistic modelling approach. Historical data of the atmospheric industrial environment conditions for five years on three metals- zinc, iron and steel with known thicknesses were used. The environmental conditions included precipitation, wind speed, sulphur dioxide, relative humidity and temperature. For the five-year period, the percentiles of corrosion in the environment were determined to be from 63.1% to 69%. The corrosion rates of Zinc, iron and steel were 0.92µm/year,0.9µm/year and 0.51µm/year respectively. At the end of the first year the expected time to initiate corrosion growth maintenance actions for zinc, iron and steel were 9 years, 10 years and 14 years in that order. The probable contributions of each of the environmental factors to the corrosiveness of the environment were determined.