Corrosion factors

Techniques for controlling the corrosion factor can be categorized into... 

The choice of the metal (Section 22.4) for the grounding electrode will depend upon the corrosion factor of the soil. Btit all metals are equally good and possess a life span of 12 years and more. For a longer working life, the thickness of the electrode may be increased as discussed in Section 22.4.1. Gl being a more... 

For a power station, assuming a corrosion factor for a lifespan ot 40 years as 0.12 mm/year then... 

Corrosion Probiems in Service. The wide variety of corrosive factors that are present in refining and petrochemical processing (e.g., acids, caustics, chlorides, sulfides, sulfates) give rise to a wide variety of corrosive attacks, some of which act ... 

Naphthenic acid is a collective name for organic acids present in some but not all crude oils. In addition to true naphthenic acids (naphthenic carboxylic acids represented by the formula X-COOH in which X is a cycloparaffin radical), the total acidity of a crude may include various amounts of other organic acids and sometimes mineral acids. Thus the total neutralization number of a stock, which is a measure of its total acidity, includes (but does not necessaiily represent) the level of naphthenic acids present. The neutralization number is the number of milligrams of potassium hydroxide required to neutralize one gram of stock as determined by titration using phenolphthalein as an indicator, or as determined by potentiometric titration. It may be as high as 10 mg KOH/gr. for some crudes. The neutralization number does not usually become important as a corrosion factor, however, unless it is at least 0.5 mg KOH/gm. 

Obrecht, Malvern F. PhD. Steam and Condensate Return Line Corrosion. Factors That Accelerate It, Retard Tt, with Emphasis on Oxygen. Heating, Piping Air Conditioning, USA, August 1964. 

For economy in construction and operation of plants for handling saline water, particular attention must be paid to corrosion factors. Steel can be used in many applications, if it is protected by the use of coatings or is given cathodic protection. Allowance also can be made in the design for the corrosion of steel. If it does not conflict with other design factors, incoming sea water should be deaerated to control steel corrosion. Corrosion inhibitors and chemical treatment may be employed to reduce the attack, but frequently this method is too costly. 

Nair, M.P.S., Control Corrosion Factors in Ammonia and Urea Plants , Hydrocarbon Processing, 80 (1), pp. 85-93, January 2001. 

Corrosive Factors in Service Intergranular Corrosion (attends carbide precipitation if electrolyte present)... 

A common approach to preventing or limiting corrosion is to eliminate contact with the corrosive factors. The simple act of washing off road salt removes the ionic solution from auto bodies. Iron objects are frequently painted to keep out O2 and moisture, but if the paint layer chips, rusting proceeds. More permanent coatings include chromium plated on plumbing fixtures. 

The corroding metal potential is inconstant since it is affected by corrosion factors var3ung in time. As soon as the electrochemical corrosion becomes stationary, the electrode potential acquires a constant value Ecorr- Once the stationary potential or the corrosion potential has stabilized, velocities of the anodic (1.2) and cathodic (1.3) reactions on the electrode equalize. Ecorr measured in standard conditions relative to some standard reference electrode... 

The analysis of corrosion factors during polymer-metal pair wear has proved that the main path is electrochemical protection of the metal counterbody neutralization of corrosion agents formed in the friction zone and suppression of corrosion processes in the polymer-metal contact. These directions are realized by the means illustrated in Fig. 4.6 [37]. They are subdivided into two groups according to the use of special substances or physical fields and power effects. 

L. Pinchuk. Corrosion factor in metal-polymer wear. Proc. 5th Intern. Sympos Intertribo-93 , Bratislava, 1993, Vol. 3, pp. 52-56. 

Obviously when we deliberately add sulfuric acid to cooling water, we reduce alkalinity and also depress pH. This increases corrosivity of the circulating water, which is saturated with dissolved oxygen, contacts many dissimilar metals, and is elevated in temperature. In the process of acidification to prevent scale deposition so heat transfer equipment will function efficiently, we knowingly build in added corrosion factors and increase corrosion control difficulty. Now we need to find corrosion inhibitor combinations which will be practical for use in industrial systems can be tolerated from the viewpoints of toxicity and pollution controls and will effectively protect these multimetal circuits during their normal service life of 20 to 30 years. 

The surface of a material or component is subject to various environmental influences when in use. The mechanical, thermal, and chanical corrosive parameters may act individually or two or even three factors can combine, the significance of each differing according to the type of stress. The corrosive factor, as shown in Figure 20.19, can be divided into chemical and electrochemical components. 

Conditions in which corrosion occurs Need to consider corrosion in design A definition of corrosion Factors which limit corrosion Effects of rust... 

Shape, orientation, and mass of the zinc-coated steel have an effect, mainly because of the effect of time of wetness but also because of a differing facility to receive deposition from the atmosphere (as already discussed in relation to sulfur dioxide). The effect of diameter of wire was shown by Richards (1938) in 5-year tests in 15 U.K. sites of widely varying corrosivity (factor of > 5), where 2 mm wire corroded 15-20% more than 4 mm wire. The results were generally similar to those of Reinhart (1961) at 11 U.S. locations on wire, wire strand, barbed wire, and fencing. The specific weight... 

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