Field corrosion

D. Hawke, J. Davis, and R. Eekete, Field Corrosion Peformance of Magnesium Powertrain Components in Eight Truck, Technical Paper 890206, Society of Automotive Engineers, Detroit, Mich., 1989. 

A considerable catalyst to the corrosion monitoring market has been expansion in the production of oil and gas, not only in the usual oil areas (US and the Middle East), but also the offshore developments in Europe. In addition to the usual uncertainty of the onset or progress of internal corrosion in the operation of plant, the oil industry has to face the considerable problem concerning prediction of field corrosivity and the possibility of the producing field becoming corrosive or more corrosive as depletion progresses. These factors have considerable influence on the installation of corrosion monitoring as oil and gas production is the major user of such equipment. 

Britton, C. F., The Selection, Evaluation and Testing of Oil Field Corrosion Inhibitors , Seminar The Development and Use of Corrosion Inhibitors , Oyez Scientific and Technical Services Ltd., London (1983)... 

Comeau, B. D., and Marsden, C. J., Unexpected Field Corrosion Leads To New Monitoring with Revised Predictive Model , Oil and Gas J., 45-48, 1 June (1987)... 

J. A. Alford, P. G. Boyd, and E. R. Fischer. Acid-anhydride esters as oil field corrosion inhibitors (ester acide anhidride comme inhib-iteur de corrosion dans le domaine des huiles). Patent FR 2692283, 1993. 

Fig. 8. Schematic diagram showing the first step in field corrosion of a two-electron bond. I — X = heat of binding x = work function n = Fermi level a/2 = expectation value of eleetron-to-surface distance.

It is common in corrosion laboratories and in field corrosion monitoring probes to immerse two vertical rods parallel to one another in an electrolyte. In the lab, one of the rods consists of a high-density graphite counterelectrode while the other is a working electrode. A reference electrode may be placed in between the two rods. In the field, polarization resistance or electrochemical noise measurements are often made between two nominally identical rods that both consist of the material of interest. The primary current distribution is nonuniform with respect to circumferential position about each electrode when the distance between the two rods is small in comparison to the radius of the rod, Fig. 10a (16). Again, the value of Ra varies from where the rods face each other to where they... 

The geometries discussed above are relevant to laboratory scale experimental cells. The geometries discussed below are more appropriate for situations encountered in industry or practical application involving galvanic corrosion, cathodic protection, or field corrosion probes. 

The high levels of calcium sulfate in Montreal are indicative of the heavy use of road salts, especially calcium chloride, and of the acid deposition that affects that area. Field corrosion tests showed how aggressive this environment can be even when the solution can quickly run off and evaporate lab tests indicate that after dying out and reacting with calcium chloride, the acid deposition may no longer be important to the corrosion process unless it is renewed. 

For the next 90 minutes or so let us explore this field - CORROSION. We shall travel in two distinct ways. One is to bring your attention to arrays of key words and concepts. The other is to formulate a pattern of solid state surface structural chemistry which may be useful as a framework for remembering complex options and for exploring new options. The latter will be within two areas (1) exchange current descriptions of corrosion potentials and (2) the nature of corroding surfaces. 

Corrosion inhibition is used internally with carbon steel pipes and vessels as an economic corrosion control alternative to stainless steels and alloys, coatings, or non-metallic composites. A particular advantage of corrosion inhibition is that it can be implemented or changed in situ without disruption of the process. For example, in processes that produce environments of increasing corrosivity with time, such as souring oil fields, corrosion can be effectively controlled with a suitable inhibitor. 

Corrosion is the effect of unwanted chemical reactions on the structures and properties of metals and alloys. For engineers out in the field, corrosion means delays and production problems. Corrosion can be further defined as the deterioration of any material in contact with its surroundings. Therefore, engineers will not only have to deal with corrosion of metals but also to corrosion of plastics, wood, concrete, protective coatings, and roofing. 

Ramniceanu, A., Weyers, R.E., Anderson-Cook, C. and Brown, M.C. (2006). Measuring the Field Corrosion Activity of Bridge Decks Built with Bare and Epoxy Coated Steel. Journal of ASTM International. 

Kruse, C.-L., Friehe, W., Schulze, M., and Schwenk, W. (1987). Field corrosion tests on hot dip galvanized steel pipes. Assessment of long-term data. Werkst. Korros., 38, 229-233 (in German). 

Sample tests in the field, corrosion test specimens, electrical resistance (ER) probes, or stressed samples exposed to the process environment. 

Severed nonelectrochemical techniques for field corrosion assessment are the measurement of spalled eind delaminated concrete from visual and chain drag operations. A measurement of the chloride contents at the reinforcing level also gives some idea as to the potential corrosion activity with chloride contents of 0.9 kg/m (1.5 Ib/yd ) typically being considered to be the threshold value for corrosion initiation. 

FIG. 12—The logic diagram for new field corrosion testing to determine the Corrosion Rate Break produced water level for carbon or low alloy steel corrosion, corrosion Inhibitor application, and corrosion resistant ailoy selection. 

The buildup of soluble corrosion products can be used to monitor corrosion kinetics. This method has been used extensively in oil field corrosion inhibitor testing, particularly in sweet (CO2) systems with only small amounts of HjS present [29]. Iron analysis in the laboratory is most rapidly done on the bench with the Hach method (Phenantridine) [.30], although a host of other wet chemical methods are applicable. Instrumental methods include Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Argon Plasma Spectroscopy (ICAP). While both these methods are well suited for high volume routine analysis, care must be taken that the samples are not contaminated by even traces of hydrocarbons. This includes soluble hydrocarbons such as methanol, chelating compounds such as EDTA, or scale inhibition products. Also used in the laboratory is Ion Chromatography (IC). This latter method is even more sensitive to sample composition and not recommended on a routine basis. 

Haynes, G. and Baboian. R., "Field Corrosion Testing and Performance of Cable Shielding Materials in Soils," MP, September 1989, pp. 68-74. 

Field corrosion testing consists of coupon testing and probe testing. Coupon exposure times typically rtinge from one to three months. Probes are exposed for as long as a specific condition is under investigation, sometimes for the life of the process. 

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