Corrosion Prevention Measures

To select required materials for a given process, functionally and economically, feasible protective measures should also be considered. 

Basically, protection comprises those measures providing separation of metal surfaces from corrosive environments, or those that allow adjustment or altering of the environment. The following sections give an outline of corrosion prevention measures. 

Corrosion prevention aims at removing or reducing the effect of one or more of the conditions leading to corrosion using the following measures.  

1 Seleeting a material that does not corrode in the actual environment. 

2 Changing the environment, e.g. removing the oxygen or adding antieorrosion chemicals (inhibitors). 

3 Using a design that will avoid corrosion, e.g. preventing the colleetion of water so that the metal surfaee can be kept dry. 

4 Changing the potential, most often by making the metal more negative and thus eounteraeting the natural tendency of the positive metal ions to be transferred from the metal to the enviromnent 

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In such cases, the third parties in question have little or no control over the use of suitable corrosion control measures. Thus, in such cases where the savings from corrosion prevention measures accrue to different persons or bodies from those who would have to bear the costs of the corrosion prevention measures, then the government alone can tax such beneficiaries for the overall benefit of the community. 

The costs incurred unnecessarily either by an industrial organization or by the community could be probably reduced by an improvement in the available information dissemination process for corrosion prevention measures. 

The purchase of corrosion prevention measures in consumer goods is similar to the purchase of safety features in automobiles such as seat belts in cars. The purchaser may not pay for this feature although the long-term benefits in saving lives and money are present. In the case of automobile safety measures, the dilemma for the community is resolved by the government regulation of mandatory use of seat belts in automobiles. In the case of corrosion prevention measures, government intervention could lead to improved corrosion prevention awareness and practice. 

At this point the author would consider any use of the proven corrosion inhibiting admixtures for new construction to be an effective corrosion prevention measure if backed up with proper assessment and whole life costing. However, any application of inhibitors for repair of existing structures should be done on a trial basis with proper long-term monitoring of the treatment. 

Batteries and capacitors Corrosion prevention Measuring and controlling devices... 

Corrosion prevention measures described in detail in Chapter 4, such as cathodic protection and inhibition treatment, are applied to aluminum. Cathodic protection is to be apphed with care, as over-protection results in developing an... 

Corrosion prevention measures have included even more stringent water treatment and removal of problematic corrosion product deposits. Chemical cleaning guidelines have been established for critical areas, and a robotic device for inspection and high-water-pressure cleaning of crevice geometries has been developed. 

Co-operate with prodnction control on adjnstment of corrosion-prevention measures to suit both parties and amend working drawings and schednles accordingly. 

In cases where the salt concentration is between 1 and 10 ptb, corrosion prevention measures should he provided. 

If the salt concentration is over 10 ptb, a desalter must be provided to reduce it to under 1 ptb, or it should he reduced to around 1 ptb and corrosion preventive measures provided. 

For the third step, if the determined total wall thickness (mechanical + CA) is not acceptable, great effort should be exercised to select and evaluate a suitable corrosion prevention measure to lower the required corrosion allowance. Some of these measures cannot withstand the process conditions, e.g. temperatures too high for polymer lining, no facilities for chemical injection, no continuous electrolyte for cathodic protection, and so on. 

In discussing various corrosion preventive measures, it is useful to consider that corrosion of the type described here, that is, attack by an aqueous liquid on a metal, has three prerequisites ... 

These expenses are not deducted directly from operating income and hence bear a less favourable tax position. Such generalizations, of course, may vary with individual companies and their accounting systems. Economic evaluation should be performed before selecting the type of corrosion preventive measure, because the success or failure of a corrosion prevention program depends on economic feasibility as well as on technical performance. A plant engineer who recommends a preventive treatment to his management should be conversant with economic evaluation and justification (see also Clause 13 Part 1 and NACE Standard RP-02-72,1972). 

One of the maj or ways of protecting oil and gas production and operating systems against corrosion is by applying corrosion inhibitors. The corrosion inhibitors are evaluated in order to determine if the corrosion preventive measures applied are necessary, and if the required lifetime can be achieved with a particular inhibitor, as the effective life of corrosion inhibitors varies with the quantity of water intrusion. The purpose of this chapter is to evaluate the on-line monitoring of corrosion and corrosion inhibitor effectiveness under different conditions. 

Those geometric forms should be chosen that can assist in securement of optimal results from the selected corrosion preventive measures, at their initial application, and at any future repetitive application. 

D2 Suggest an appropriate material for each of the following apphcations, and, if necessary, recommend corrosion prevention measures that should be taken. Justify yom suggestions. 

Not only is there a direct and indirect financial burden, but corrosion also has a considerable societal impact. Crucial industries such as energy, aerospace, transportation, food, agriculture, electronics, marine, and petrochemical rely on the safety and availability of their infrastructures. In many instances, these requirements have been compromised by corrosion events that have led to loss of life, enviroiunental pollution, and loss of jxrwer to industry. However, between 25 and 50% of the economic impact (depending on the specific industry) could have been prevented by the use of well-accepted materials selection and corrosion prevention measures. 

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