Material selection must be done in the actual usage environment; otherwise, the results will vary significantly
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The selection of materials must be done in the actual operating environment; otherwise, the results will vary significantly. Problem: The hydrogen chloride gas scrubbers and mist eliminators in a certain factory were originally made of reinforced phenolic plastic, and they could only last for 2 to 3 years. To select more corrosion-resistant materials, coupon testing was conducted on washers and demisters, showing that Hastelloy C-276 (with a composition of 00Cr16Ni57Mo16Fe6W4) can be used for washers, while alloy 20 (chromium-nickel stainless steel) can be used for demisters. However, the equipment manufactured from these high-grade corrosion-resistant alloys was corroded and damaged within two weeks and four weeks respectively. Analysis: The reason why the actual corrosion behavior of the material differs significantly from the results of the coupon test is that the coupon was not placed in the correct location – it was exposed to the gas phase rather than to the washing solution – as a result of which the experimental conditions differ greatly from the actual environmental conditions. Note: Conducting coupon tests inside the production equipment has a great advantage for evaluating the corrosion resistance of materials under the environmental conditions present in that equipment, namely the authenticity of those environmental conditions. Whether true environmental conditions can be achieved depends on the design of the experiment, with the most important factor being the correct selection of the location for the test samples. The sampling location should be representative and able to reflect the main characteristics of the corrosion conditions of the equipment.
Yes, during the hanging test, it is necessary to ensure that the environment in which the sample is hung is identical to the actual operating environment of the equipment. If the test pieces are located in the gas phase rather than in the washing solution, the corrosion resistance values obtained cannot accurately reflect the performance of the material under actual operating conditions. Choosing the correct position for the hanging slice is key in experimental design. .
What you said makes sense; thanks, President Wang, for sharing this information!
I fully agree with your suggestion; knowing how to hang the slices is also a skill in itself