Corrosion evaluation testing

Two types of corrosion evaluation tests, SO2 and Prohesion salt spray tests, were employed for the evaluation of corrosion protection characteristics of painted plasma systems. The SO2 salt spray test was chosen to speed up differentiation of the corrosion protection properties of the different systems investigated. The Prohesion... 

Sensitized material that fails corrosion evaluation testing may perform perfectly well in service. The highly oxidizing... 

Specifying corrosion evaluation tests may lead to significant delay in delivery of material. Suppliers do not normally include such tests as a prerequisite to releasing materials because the majority of the market does not require this form of testing. Now that dual marked stainless steels predominate the market, the requirement for corrosion evaluation should be questioned, except for certain nickel-chromium alloys. 

VFO works well in gas turbines. In a nine-month test program, the combustion properties of VFO were studied in a combustion test module. A gas turbine was also operated on VFO. The tests were conducted to study the combustion characteristics of VFO, the erosive and corrosive effects of VFO, and the operation of a gas turbine on VFO. The combustion tests were conducted on a combustion test module built from a GE Frame 5 combustion can and liner. The gas turbine tests were conducted on a Ford model 707 industrial gas turbine. Both the combustion module and gas turbine were used in the erosion and corrosion evaluation. The combustion tests showed the VFO to match natural gas in flame patterns, temperature profile, and flame color. The operation of the gas turbine revealed that the gas turbine not only operated well on VFO, but its performance was improved. The turbine inlet temperature was lower at a given output with VFO than with either natural gas or diesel fuel. This phenomenon is due to the increase in exhaust mass flow provided by the addition of steam in the diesel for the vaporization process. Following the tests, a thorough inspection was made of materials in the combustion module and on the gas turbine, which came into contact with the vaporized fuel or with the combustion gas. The inspection revealed no harmful effects on any of the components due to the use of VFO. 

It should be noted that although ASTM A262 1986 provides details of test procedures no information is given on typical corrosion rates or acceptable limits for various heat-treated alloys, which are regarded as outside the province of a specification that describes test procedures. Table 19.4, taken from a paper by Brown, shows the maximum acceptable evaluation test rates specified by the Du Pont Company for various alloys tested by the acid... 

Skin irritation or corrosivity evaluation or in vitro tests... 

Computers and programs are also important in corrosion monitoring systems, such as an automated constant rate extension system (A Cert) shown schematically in Figure 5.5. This system may be used for conducting corrosion and cracking evaluation tests. The system is capable of initiation and conducting tests as well as data acquisition and analysis. There is very little human intervention and the system is capable of corrosion evaluation in environments which are difficult to simulate. This system is a... 

Table 2a Primary data (n) of salt spry test cabinet corrosivity evaluation in eight experiments as corrosion rate (v, mg/m2) of RS (average mass m=31225 mg) mass loss (Am, mg) from their geometric surface area (S, mm2) (first four experiments)...

Many types of nondestructive, leak, corrosion evaluation and mechanical tests may be used to establish and verify quality requirements of the materials specification. In addition, identification markings enable materials to be checked for specification conformance. Field identification methods must be used when all else has failed, but their limitations must be understood. 

Uniform surface corrosion is generally the result of chemical attack by the reaction medium. It can be facilitated by erosion of a passivating layer. A well-known example is scaling of iron surfaces due to oxide formation with hot air. Studies on uniform surface corrosion require test times of 1-2 months, since the attack is more intense in the early stages. The following ranges of corrosion rates can be used for general evaluation ... 

Materials evaluation in pilot plants covers all phases of the coal gasification process. Test specimens are installed in the coal pretreatment, gasification, gas quench systems, and methanation equipment in the plants. Three exposures, nominally 1, 3, and 6 months, at plant operating conditions are scheduled for each test location. Post-exposure corrosion evaluation employed in Phase II are the same as those used in other phases of the IITRI program, i.e., metallography combined with gravimetric analysis. 

Corrosivity indicator tests normally used to evaluate BA or BS are pH, electrical resistivity, soluble chloride content, and soluble sulfate content. Materials are judged to be noncorrosive if the pH exceeds 5.5, the electrical resistivity is... 

H.P. Hack, Evaluating Galvanic Corrosion, in Corrosion Fundamentak, Testing and Protection, ninth ed., in ASM Handbook, Vol. 13A, ASM, Metals Park OH, 1987, pp. 562—567. 

Friedersdorf FJ., Holcomb R. Pin-on-disk corrosion wear test. Journal of Testing and Evaluation JTEVA, 26(4) 1998 352-357. 

Due to the wide range of condition for corrosion occurring, there are many tests to evaluate corrosion. These tests include the study of atmospheric corrosion, corrosion during episodic wet/dry conditions, corrosion under fully immersed conditions, corrosion in soil, corrosion in aqueous solutions and corrosion in non-aqueous solutions and in molten salts. Moreover, it is important to consider the in-service environment and the objectives of the tests being performed. 

The dissolution of material into an aqueous solution and so on, has a merit as well as a demerit to the enviroimient. Consider coated materials for an example. One of the objectives of a surface treatment such as plating is to improve corrosion resistance. In this case, it is preferable that the materials do not dissolve in water. This improvement of corrosion resistance enables the long-term use of materials, and will contribute to the reduction of resources and energy required for materials production. In Japan, JIS (Japanese Industrial Standards) H8502 (1999) regulates the methods of corrosion resistance tests for metallic coatings so as to evaluate the corrosion of a material. This standard includes the ISO 4540 (1980), ISO 4541 (1978) and others. 

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