Corrosion testing continued applications

Deflagration Arrester Testing For end-of-line and tank vent flame arresters, approval agencies may require manufacturers to provide users with data for flow capacity at operating pressures, proof of success during an endurance burn or continuous flame test, evidence of flashback test results (for end-of-hne arresters) or explosion test results (for in-line or tank vent arrester applications), hydrauhc pressure test results, and results of a corrosion test. 

A dense and electronically insulating layer of LiA102 is not suitable for providing corrosion resistance to the cell current collectors because these components must remain electrically conductive. The typical materials used for this application are 316 stainless steel and chromium plated stainless steels. However, materials with better corrosion resistance are required for longterm operation of MCFCs. Research is continuing to understand the corrosion processes of chromium in molten carbonate salts under both fuel gas and oxidizing gas environments (23,25) and to identify improved alloys (29) for MCFCs. Stainless steels such as Type 310 and 446 have demonstrated better corrosion resistance than Type 316 in corrosion tests (29). 

The use of surface tools need not be limited only to thin layers or small dimension corrosion. Creative application of surface methods to larger scale corrosion products, more characteristic of industrial problems, has provided useful information not previously available. More sophisticated uses of surface methods that are being developed and tested continually will provide even more information for corrosion research. 

Second precondition. Dissolution of iron will take place only when the current circulates for sufficiently long periods and in high enough intensity to produce acidity that can destroy the conditions of passivity. For instance, Figure 9.6 show the results obtained with laboratory tests on specimens of cement paste subjected to the circulation of current densities of 1 and 10 A/m [5]. Corrosion initiated on steel embedded in cement paste without chloride ordy after more than 200 h of ap-pHcation of an anodic current density of 10 A/m. A current density of 1 A/m could not initiate corrosion even after 14 months (i. e. more than 10000 hours) of continuous application, although the charge that circulated (> 10000 A -h/m )... 

The corrosion test methods may be any method that can provide corrosion data in the low water environments. This is generally coupon testing, but may include electrochemical tests that are applicable to the high resistivity crude oil continuous environments at low water levels, e.g., electrochemical impedance spectroscopy and electrochemical noise. 

This type of work is not an exact science. Consequently, other inspection and measurement methods are employed as an aid in identifying corrosion, deposition buildup, structural integrity flaws, and other types of problems. Methods employed generally are various types of NDT, and the protocols are widely used in preventive or predictive PV maintenance programs, especially for boiler plants used in continuous process applications, where a shutdown may be several years hence. Nevertheless, there is a drawback to the use of some types of NDT programs in that lengthy downtimes may be necessary to complete the testing work. Clearly, these can be cost-prohibitive. 

Panels were prepared using an airless spray in accordance with the manufacturer s instructions. The manufacturer s specification recommended the product for applications involving immersion in well fluids up to 150 C. The product was tested at 150 °C in well fluids supplied by Amerada Hess from the Scott Field (North Sea). Permeation and corrosion occurred both in the gas and water phases of the test panel after only 3 days continuous service. Further testing in water only confirmed rapid breakdown at 100 C after 1 week s immersion. 

It has been shown [74] that this condenser results in lower corrosion rates than the Allihn condenser. The lowest rates are obtained with (glass) apparatus in which there is continuous flushing of (chromium) corrosion products [6,74]. A design for such conditions has also been provided by Corbett [38]. In this apparatus, up to 100 specimens can be tested simultaneously with corrosion products kept so low that the test simulates a once through industrial application. 

Constant deflection tests usually have the attraction of employing simple, and therefore frequently cheap, specimens and straining frames and of simulating the fabrication stresses that are most frequently associated with stress-corrosion failure. Constant load tests may simulate more closely failure from applied or working stresses. Tests involving the application of a constant deflection rate have become fashionable in recent times but their relevance to service failures continues to be debated. 

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