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Eds, Any specific public reference or failure report you have related to the local galvanic effect by Silicon carbide? (The reason why I am asking is due to that sometimes I review vendor documents and possibly find the use in future and need to recommend another one explaining the reason.) I...

Check with the chemical vendor whether they are compatible each other. There are some cases that oxygen scavenger can interfere biocide's activities. ( ex., oxidizing biocide requires oxygen to kill bacteria so it shall be applied before scavenger injection or non-oxidizing one is to be...

Eds, Is there any available reference that nitric acid can work for the case contaminated by embedded iron in "Nickel alloy"(Not stainless steel)? (Any published book??) (Please note that I am not attacking you but hope to confirm it by reference and find any other useful information. Actually...

Eds, note that my input is based on reliable reference like ASM. Regarding the formula 12, refer to the below link. You can check it whether true or not. ("Detection and Removal of Embedded Iron.")...

Generally, the best method for nickel alloy is just mechanical cleaning followed by flashing pickling. However, steel & brass brush must be avoided as small particles of steel & brass can discolor nickel alloy or induce rust. I believe your case is exactly same as the one described in ASM Metal...

Eds, Thanks for the input. Is the "simple passivation" common? I have never heard the actual case that there is kind of cleaning without removing rust but only for the limited usage. I appreciate if you share the case when only the "embedded" Fe is to be removed. SiHyoung Lee

Tapering, hydrotest...These would be the keywords... Check whether there is sufficient thickness kept after tapering. Generally, tapering, which is to reduce stress concentration by placing in elastic zone of stress & strain curve, could induce thickness reduction over threshold limit...

The main purpose of acid cleaning includes removal of rust and forming protective oxide film again. If the acid cleaning had been properly carried out, there shouldn't have been any rust present. While mechanical cleaning like brush is physically to remove impurities (such as weld spatter), acid...

FYI https://www.steeltank.com/Portals/0/Pressure%20Vessels/SSWseminarOct2012/Relative%20Cost%204%2015%202012.pdf SiHyoung Lee

Reference from Figure A8-2 "Material Selection for hydrocarbon and chemical plant, David Hansen" (Note that it is a guideline of Cl SCC.) 1. Time to failure at 2,200 ppm of chloride at 250 C - 20 hours 2. Time to failure at 2,200 ppm of chloride at 150 C - 15,000 hours 3. Time to failure at...

Generally, corrosion failure for the stripped water is not common. If you are confident that the oxygen has been controlled for sure, you need to carry out failure analysis to analyze the corrosion product. (By the way, I assume CO2 value is also negligible. If not, review it from CO2 corrosion...

Sour water corrosion occurs mostly at the overhead section, not most likely for the stripped water. Actually, reboiler located at the bottom of sour water stripper handles with "stripped" phase (corrosive component is off to the top). Also, regarding pH, the stripped water is not acidic for most...

Have you checked oxygen content or possibility of the ingress? SiHyoung Lee

The most important thing to prevent ethanol stress corrosion cracking is to keep it with "free of oxygen". It has not been reported for the environment under deaerated conditions. (Reference from API RP 571) Hence, corrosion monitoring like IOW should be established and design of purging system...

Try the below way. Calculate the volume of each coating and multiply it by density of the coating. Then, the outcome will be weight. The surface area that FBE coating(Outer surface) * the DFT of the FBE coating (Max DFT recommended) * the density of the FBE coating + The surface area that ARO...

Yes, it falls under acceptable range from Table A.24 of ISO-15156. Note that it shall be oxygen-free system. SiHyoung Lee

Note that NACE PAPER NO 34109 is not related to CDU charge heater. Referring to the title of the paper, it is NACE Publication 34109-2009, Crude Distillation Unit—Distillation "Tower Overhead" System Corrosion" Generally, temperature at CDU Tower overhead is not more than 500F. Hence, it is...

Yes, it is. You can also confirm QW-407 of ASME Sec IX as per the welding method that PWHT is "essential" factor. Hence, PWHT on actual WPS shall be aligned with simulation test of the PQR. Lee SiHyoung,

PWHT is not mandatory based on ISO-15156 although it is one of the best ways to comply with the hardness requirement. But in case PWHT is possibly applied due to any reasons(ex., fails to comply with hardness), PQR shall cover the property on the expected number of cycles by PWHT. Sihyoung Lee,

Forough64, Note that the surface protective film on steel does not always stay in stable film. The oxide film(ex., Cr2O3) can be decomposed in case it is exposed to specific environment like strong acid. The reason why corrosion resistance of nickel based alloy or titanium alloy is generally...