[Weekly Topic] Corrosion and Protection: Talking about Things at Work (2011.9.19-2011.9.25)
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Dear colleagues: Corrosion is a common issue in our chemical enterprises, and it is essential to carry out proper protection measures. Please share what work was done regarding corrosion and protection in your respective companies over the past week. We also welcome suggestions for effective practices so that we can learn from one another and improve our efforts in preventing corrosion. Notes: 1. It is preferable to provide examples that occurred this week; a single incident can be described, such as: gasket damage at xxx location, with details on the replacement carried out ； It is also possible to conduct a deeper analysis of the reasons: such as aging over time, or the presence of organic solvents mixed in the medium ； 2. It must be related to corrosion and protection ； 3. I hope everyone will participate actively.
Years of leakage from underground circulating water pipes have caused seepage on the ground surface. During the excavation of the pipeline for maintenance, it was found that the underground pipes were not protected against corrosion using the proper \"three oils and two fabrics\" method, which led to corrosion of the pipes. Learning from the lessons, cutting corners has harmed the company.
The expansion joint of the sulfur trioxide gas pipeline, which has been in use for ten years, is leaking frequently recently; this is likely related to its service life, with corrosion being another important factor
Today, 4 meters of pipe were replaced. The pipe branches from a straight section and then leads into the regulation tank; a leak was detected at the elbow just before it enters the tank, and welding was not possible, so the pipe had to be replaced. After removal, it was found that the bottom of the pipe was severely corroded, especially in areas where water tended to accumulate at the elbows. Reset the settings and adjust the slope from high to low to ensure no water remains in the pipeline.
The inlet pipe in the pump room was replaced; after removing the pipe, it appeared to be quite thick. After rust removal and cleaning of the sludge using steel plates, its thickness was reduced to only 1-2 MM. The pipe is a DN200 seamless steel pipe. The corrosion is very severe. What was replaced again is that there weren’t enough 304 tubes, so it will be replaced once more tomorrow.
The two reboilers in the benzene extraction system leak frequently, and they need to be replaced entirely every seven or eight months. The solution involves reducing the gas phase temperature to as low as 180 degrees, as well as redesigning the reboilers to provide more expansion space.
The anti-corrosion treatment for the outdoor pipes has finally been completed. To enhance corrosion resistance, some pipes are to be coated with an additional layer of impregnated glass cloth, with work set to begin next month.
For atmospheric pressure storage tanks, cathodic protection technology involving aluminum spraying on the outer surface is used.
The sewage pipelines in our plant have been in use for 20 years, and there are leakage issues at certain points. A macroscopic inspection of the leaking pipelines revealed numerous corrosion pits on their surfaces, which is a typical sign of pitting corrosion. Thickness measurements of these leaking pipelines showed that their thickness had significantly decreased, with the thinnest areas being only about 2 mm thick. As a result, the pipelines were replaced on site.
The existing pool was inspected; the glass cloth protective layer of the pool was mostly intact, but the anti-corrosion coating on the top of the pool was severely damaged. The entire pool is set to have its anti-corrosion protection renewed using glass cloth.
Yesterday, the biogas bypass pipe was replaced, mainly due to minor leaks caused by corrosion. After the pipeline was removed and inspected, it was found that the lower half of the pipeline was severely corroded. This was attributed to the presence of H2S gas and moisture in the biogas, which created a corrosive environment; the pipeline had been in use for 5 years. Based on the above conclusions, preparations are being made to proceed with replacing the remaining pipe sections