Showing papers in "Materials Performance in 1986"

Role of bacterial exopolymers in the deterioration of metallic copper surfaces

Abstract: Les polymeres microbiens qui accrochent des cellules aux surfaces presentent une liaison des ions cuivre en suspensions aqueuses, fortement influencee par le pH. Ils engendrent egalement la deterioration d'un film metallique de cuivre plonge dans l'eau

Diffusion of dissolved oxygen through concrete

Abstract: This article describes investigations of the rate of steel corrosion for concrete structures in the ocean. Experiments compared the diffusion of dissolved oxygen through submerged concrete of different qualities and thickness. For a given quality, the flux of oxygen was not proportional to thickness, and for a given thickness not directly related to quality. For the same W/C-ratio, diffusion was lower through mortar than through concrete. The flux was about 10 times lower through a specimen with two cast surfaces than through one with two cut surfaces. The most significant effect on the rate of oxygen diffusion resulted from a twin layer of cement paste on the concrete surface.

A laboratory evaluation technique for predicting the behavior of organic coatings in FGD systems

Abstract: Resultats d'essais d'exposition d'acier au carbone revetu de diverses resines, a de l'acide sulfurique dilue a 60°C, pendant 3000 h. Comparaison avec un essai sur le terrain de 18 mois

Study of biological corrosion in high temperature demineralized water

Abstract: Resultats d'essais de corrosion biologique localisee d'acier inoxydable AISI 304. A haute temperature, on a une seule espece microbiologique dans de l'eau mineralisee relativement pure

Soluble silicate corrosion inhibitors in water systems

Abstract: Utilisation de silicates de sodium dans les canalisations d'eau: conditions d'utilisation, duree et effets du vieillissement; dosages conseilles. C'est un produit peu couteux, non toxique et ne contribuant pas a l'eutrophisation

Mechanisms of organic inhibitors used in cooling water corrosion control

Abstract: Use of heavy metal-based corrosion inhibitors is being curtailed by environmental restrictions. In many parts of the world, high levels of inorganic phosphates are also restricted. In answer to these restrictions, more environmentally acceptable programs based on organic compounds have come into use. Some of these organic compounds have long been used as scale inhibitors. This paper details how these compounds can also function as corrosion inhibitors under proper conditions. Their mechanism of action is discussed and the surface analytical and electrochemical techniques used for these investigations are described.

Hot-dip coated sheet steels: a review

Abstract: Revue des principaux revetements: zinc, aluminium, et alliages fer-zinc, aluminium-zinc et plomb-etain. Methodes de production, proprietes, mecanismes de protection et applications industrielles

Effect of cathodic protection on the activity of microbial biofilms

Abstract: Impressed current or sacrificial anode systems are used to protect the subsea structures of offshore oil platforms and rigs. The steel is considered protected when a potential of -850 mV(Cu:CuSO/sub 4/) is achieved, in many cases, the potential is further reduced to -950 mV to protect the steel from corrosion caused by the activity of sulfate-reducing bacteria (SRB). Therefore, some operators have questioned the presence of sulfide-containing deposits under marine macrofouling, indicating that SRB are active on structures protected to -950 mV. The decreased potential, however, is not applied to prevent the activity of SRB, but is based on a theoretical level which will allow passivity of steel in sulfide environments. This study was performed to determine the effect of a -950 mV cathodic potential on the activity of the biofilm formed, and the production of sulfide within that biofilm. 50D mild steel (BS 4360 Grade5D)/sup (1)/ corrosion coupons, both unprotected and protected with a sacrificial anode, were exposed in the estuarine waters of Aberdeen Harbor. The activities of the bacterial biofilms were determined using radiorespirometric methods. Biofilms were shown to develop on both substrata. The activity of the aerobic and anaerobic bacteria and SRB populations, however, were significantly greatermore » on the unprotected coupons. Furthermore, sulfide could only be detected in the biofilm formed on the unprotected coupons. The results show that a potential of -950 mV does not prevent an active population of SRB developing on the metal surface. It is suggested that the lower activity of the biofilm on the protected coupon is not directly caused by any inhibitory effect of the cathodic potential; but that the greater activity on the unprotected coupon may be the result of the production of an extensive corrosion film that offers more favorable conditions for the activity of anaerobic bacteria.« less

Cathodic protection criteria ― a critical review of NACE standard RP-01-69

Abstract: Cette norme, sur le «controle de la corrosion externe des systemes de tuyauteries souterraines ou sous-marines», contient des criteres pour la protection cathodique des structures d'acier dans le sol et dans l'eau qui sont largement acceptes. Or, beaucoup de ces criteres sont en desaccord avec la science fondamentale et avec d'autres normes. Des etudes recentes confirment que ces criteres doivent etre revises

Alternating current corrosion

Abstract: On verifie que l'influence d'un courant alternatif de 60 Hz a une influence minime sur les pipelines proteges cathodiquement. Influence du courant alternatif sur les anodes galvaniques et sur les metaux associes aux systemes electriques

The resistance of high frequency inductive welded pipe to grooving corrosion in salt water

Abstract: When exposed to neutral, salt-containing waters, electric resistant welded pipe in carbon and low alloy steels with increased sulfur contents may suffer preferential corrosion attack in the weld area. Because of its appearance, this type of corrosion is called grooving corrosion. The susceptibility to grooving corrosion may be determined and quantitatively described by means of an accelerated potentiostatic exposure test. The importance of type, concentration, and temperature of the electrolytic solution; potential; test duration; and the sulfur content of the steel in the accelerated corrosion test and the susceptibility of steels to grooving corrosion are described. Line pipe in high frequency inductive (HFI) welded carbon and low alloy steels are resistant to grooving corrosion particularly because of their low sulfur content.

The chimical control of cobalt leaching from cemented carbide tooling

Abstract: Toxicite des ions cobalt dissous par les fluides de coupe agissant sur les outils d'usinage de composition WC-Co. Proposition d'emploi d'agents de refroidissement, agissant comme inhibiteurs de la dissolution du cobalt

Effect of silicon on the corrosion resistance of iron in sulfuric acid

Abstract: In certain cases, additions of silicon to iron-base alloys have produced significant improvements in general corrosion resistance in a variety of acids, to chloride pitting resistance, and to chloride stress corrosion cracking (SCC). The largest effect is produced by addition of 14.5% Si to iron, which make this alloy more resistant in a number of very corrosive environments than alloys with large concentrations of Cr, Ni, and Mo. This investigation was to determine the factors governing the effect of silicon (1.5 to 14.5%) in iron on corrosion in sulfuric acid solutions. The acid concentrations ranged from 5 to 70%. Measurements were made at three temperatures, 30 and 50 C and boiling. Detailed measurements of weight-losses as a function of time have been correlated with electrochemical measurements of corrosion potentials and potentiodynamic polarization. Attempts have been made to correlate these measurements with observations on the formation of solid corrosion products and protective films and with some properties of sulfuric acid solutions, pH, electrical conductivity, and redox potentials.

Standard test procedure for stress corrosion cracking threshold stress determination

Abstract: Resultats experimentaux obtenus avec trois aciers de canalisation (deux X-52 et un X-60), sur un certain domaine d'amplitude et de frequence de contrainte et pendant divers temps d'essai; afin d'identifier les valeurs optimales de ces parametres

Control of microbiologically induced corrosion and accumulation of solids in a seawater flood system

Abstract: Control of sessile bacteria (mainly sulfate reducers) is important for controlling microbiologically-induced corrosion (MIC) and suspended solids in a large seawater flood system. Bactericide treatments and mechanical cleaning are the major bacteria control methods; when combined with oxygen removal, pH control, and flow maintenance, they permit relatively troublefree operation in terms of corrosion and water quality. Coupon corrosion rates decreased from monthly averages as high as 0.5 mm/y down to <0.05 mm/y when the sessile sulfate reducing bacteria counts decreased from about 4 x 10/sup 5/ cells/cm/sup 2/ down to 6 x 10/sup 2/. A suitable monitoring program is required for a timely detection of potential problems and for treatment evaluations. Sessile bacteria counts and bactericide demand are two of the techniques found useful.

A review of stress corrosion cracking of steel in liquefied ammonia service

Abstract: Stress corrosion cracking (SCC) of steel in liquefied ammonia is traced from its early recognition in the 1950's, through agricultural and industrial experiences, to the NACE recommended Department of Transportation (DOT) regulations to prevent damage, and to extensive laboratory studies of many detrimental and beneficial factors. Based on the studies and various practical experiences, several palliative and control measures are discussed, such as control of air contamination, inhibition by water addition, postweld heat treatments, the influence of the strength of the steels used and the applied stress, and periodic inspection techniques.

Low cost, low volume, continuous inhibition of gas production tubulars

Abstract: A low cost, low volume, continuous inhibitor injection technique for gas producing conduits was developed and qualified through field studies for superficial gas velocities up to 40 ft/s (12 m/s); maximum steady-state corrosion rates downhole are below 0.2 mpy (0.005 mm/y) and on the surface below 3 mpy (0.075 mm/y). The results of this new technique collected from seven wells over several years are compared with the effectiveness of the so-called partial batch treatment, practiced on 12 wells of similar nature. The new technique results in corrosion rates that are from 2 to 6 times lower. The effectiveness of batch treatments depends on the inhibitor solution being partially squeezed into the formation, and the amount of total liquid fluids available downhole to move the inhibitor back out during normal production. The new technique is not only more effective than batch treatments but it is also less costly, and it protects at temperatures up to 400/sup 0/F (204.4/sup 0/C).

Corrosion behavior of titanium and other alloys in laboratory FGD scrubber environments

Abstract: Immersion and crevice corrosion testing of various high performance alloys in actual and representative flue gas desulfurization (FGD) scrubber liquors was performed to characterize relative alloy corrosion behavior. Correlation with previous field data identified crevice corrosion as the limiting mode of attack in hot, low pH, aerated scrubber liquors. Also, pitting limited performance of stainless steel alloys was tested. Titanium alloys exhibited superior resistance to all forms of localized attack and are shown to be resistant to smeared surface iron pitting, and hydrogen uptake when galvanically coupled to carbon steel under simulated aggressive scrubber conditions.

Corrosion of Electrical Connectors

Abstract: : Partial contents: Environmental effects on connector systems; Corrosion Mechanisms--Corrosion at Class I, II, III, and IV conditions, and Galvanic corrosion in severe marine or polluted environments; Mitigation of connector corrosion--Materials selection for connector contacts-(Gold, palladium and palladium alloys, and reactive or base metals), Minimizing fretting corrosion in connector contacts, Minimizing galvanic corrosion, Design of enclosures to minimize moisture effects, Maintenance procedures.

Case histories of deaerator failure analysis

Abstract: Presentation de 5 cas de fissuration et corrosion de soudures, zones thermiquement affectees et metal de base dans des recipients de desaeration de diverses industries. Similitude des caracteristiques de la fissuration, associees a un mecanisme de corrosion sous tension et fatigue avec corrosion

The use of AC impedance to determine the corrosion rate of electrogalvanized steel

Abstract: Les resultats experimentaux montrent que la vitesse reelle de corrosion de l'acier electrogalvanise est reliee a la valeur de l'impedance en courant alternatif de la resistance de polarisation dans le sulfate d'ammonium molaire desaere, sous des conditions voisines de la neutralite. La valeur de la capacite electrique de la double couche obtenue a partir des donnees a haute frequence est egalement reliee a la vitesse de corrosion et a la condition de la surface du revetement metallique. La variation au cours du temps de la vitesse de corrosion peut egalement etre controlee en utilisant un domaine choisi de frequence du spectre d'impedance

Performance of high nickel alloys in refinery and petrochemical environments

Abstract: In certain intermediate temperature refinery and petrochemical applications, both resistance to polythionic acid and chloride stress corrosion cracking (SCC) and high temperature strength and stability are required. The effect of simulated operating temperatures in the 900 to 1500/sup 0/F (482 to 816/sup 0/C) range on the corrosion and mechanical properties of several nickel alloys is examined.

Corrosion and economics of electroless nickel coatings in chemical process environments

Abstract: Etude experimentale de la corrosion de trois revetements chimiques de nickel contenant respectivement 1-2, 6-8 et 10-12% en poids de phosphore, sur de l'acier au carbone 1010

Temporary rust-preventive compounds for steel sheet

Abstract: Application de produits huileux, dont l'efficacite depend de la composition chimique des inhibiteurs de rouille utilises et de la quantite d'inhibiteur deposee a la surface du metal

Zirconium in sulfuric acid applications

Abstract: Zirconium is one of the few metals that resists attack by sulfuric acid at concentrations up to 75% and temperatures to boiling and above. This capability makes zirconium a good structural metal for use in 40 to 65% H/sub 2/SO/sub 4/ up to boiling temperatures and for weak acid concentrations at elevated temperatures. Zirconium's corrosion properties in sulfuric acid solutions are compared with nickel base alloys. Examples of applications and limitations in the use of zirconium are presented.

Stress corrosion cracking of c-mn steels in environments containing carbon dioxide

Abstract: Instances of stress corrosion cracking in low strength ferritic steels by environments containing carbon dioxide are discussed as they relate to the gas, chemical, and petrochemical industries. These instances are examples of cracking by carbonate-bicarbonate solutions and occur within similar ranges of potential and pH, though other species are present and themselves exert some influence on cracking. Possible reactions involved in defining the potential and pH ranges for cracking are considered and form the basis for suggesting that, for existing plants, potential control probably affords the most appropriate way of controlling the problem.

Stress corrosion cracking of carbon steel welds in amine service

Abstract: Leaks were discovered at refinery piping welds in lean amine service at temperatures that, in the past, had been considered to be below the threshold temperature for stress corrosion cracking These welds had not received post weld heat treatment Leaks were caused by intergrannular stress corrosion cracking The nature of the cracking, the extensive inspection program that was carried out to identify cracked welds, and the corrective measures that were implemented are described The cracking mechanism and possible effects of certain process variables, including the use of corrosion inhibitor containing a sequestering agent, are discussed

Alternatives to copper grounding in sites requiring cathodic protection

Abstract: Problemes poses par la protection cathodique des structures ferreuses souterraines connectees a des grilles de mise a la terre en cuivre. On discute des alternatives aux electrodes classiques de mise a la terre en cuivre. On presente des exemples d'autres electrodes et systemes de mise a la terre employes depuis 25 ans

Microcomputer corrosion analysis for structures in inhomogeneous electrolytes

Abstract: Application d'un systeme integre de programmes pour microordinateur a des problemes reels dans lesquels interviennent des conductivites d'electrolyte variables