Corrosion prevention performance testing

The total quantity of sulfur in a gear oil due to the base oil and the additives present can be determined by a bomb method (ASTM D-129, IP 61) in which the sulfur is assessed gravimetrically as barium sulfate. The copper strip test (ASTM D-130, ASTM D-849, ASTM D-2649, IP 154) is used to simulate the tendency of the oil to attack copper, brass, or bronze. Because active sulfur is desirable for some extreme-pressure applications, a positive copper strip result can indicate that the formulation is satisfactory, but care is necessary in the interpretation of copper strip results because formulations of different chemical compositions may give different results and yet have similar performance in the intended application. Corrosion preventative properties are also measurable (ASTM D-4636). 

In the meantime, parallel product development toward commercially useful and competitive anticorrosion coating systems has led to various products finding their place in the market, having been successfully tested under practical and various laboratory conditions [74]. It also became evident that the conclusions that were drawn from the basic research on dispersion and the corrosion prevention mechanism of polyaniline have led to superior performance compared to other systems, which have been proposed as alternative techniques [75,114a,114b,l 14c]. This is probably due to the fact that the alternative methods do not fulfill all chemical, physical, and technical requirements that a corrosion prevention technology based on polyaniline on a technical scale has to. 

Davidson, D., Thompson, L., Lutze, F., Tiburdo, B., Smith, K., Meade, C., et al., "Perforation Corrosion Performance of Autobody Steel Sheet in On-Vehicle and Accelerated Tests, Advances in Coatings and Corrosion Prevention, SP-1770, Society of Automotive Engineers, Warrendale, PA, 2003. 

Evidence of localized corrosion can be obtained from polarization methods such as potentiodynamic polarization, EIS, and electrochemical noise measurements, which are particularly well suited to providing data on localized corrosion. When evidence of localized attack is obtained, the engineer needs to perform a careful analysis of the conditions that may lead to such attack. Correlation with process conditions can provide additional data about the susceptibility of the equipment to locaHzed attack and can potentially help prevent failures due to pitting or crevice corrosion. Since pitting may have a delayed initiation phase, careful consideration of the cause of the localized attack is critical. Laboratory testing and involvement of an... 

By performing weight loss tests, technical personnel can estimate the corrosiveness of an environment over a period of time. If the corrosion rate is determined to be high, preventive measures can be taken to prolong the remaining life of the equipment. The preventive measures can include the addition of a corrosion inhibitor, a change in the process, an application of anticorrosion coatings, or the addition of a CP system. 

The evaluation of corrosion inhibitor effectiveness is significantly different in many respects from corrosion testing for the purpose of evaluating material performance. The addition of a chemical to a corroding system requires compatibility, chemical and thermal stability, and in some cases physical stability as well. Transport properties become important where localized or gasphase corrosion (dew point) are an issue. Finally, no corrosion inhibitor, no matter how effective in preventing corrosion, can be considered successful if it causes process upsets. This latter aspect is usually summarized under secondary properties testing [7] (cf. also Chapter 1 in this book). 

Transport of gasoline and other refined products in steel pipelines may result in corrosion products that can create a product contamination problem. Internal corrosion of the pipeline can also have an adverse effect on pipeline capacity. Corrosion results from condensation of a water film on the pipe wall plus dissolved air or SRB in the product. Corrosion control is commonly achieved by adding a corrosion inhibitor. Evaluation of inhibitor performance can be done using NACE Test Method for Antirust Properties of Cargoes in Petroleum Product Pipeline (TM0172). This test method is a modification of ASTM D 665, Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water. 

Rust problems during usage of certain refined products, such as steam turbine oils, are controlled by addition of corrosion inhibitors. Evaluation of the performance of these inhibitors is done using ASTM D 665 or ASTM D 3603, Test Method for Rust-Preventing Characteristics of Steam Turbine Oil in the Presence of Water (Horizontal Disk Method). 

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