Have you ever encountered corrosion of carbon steel heat exchanger tubes caused by circulating water?
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Have you ever encountered corrosion of carbon steel heat exchanger tubes caused by circulating water? (Used for 3 years; often found leaks in the pipes, with water seeping out of the casing)
It shouldn’t be; what’s moving inside the shell?
Under normal circumstances, corrosion of circulating water is inevitable, especially general corrosion; as long as the corrosion rate remains within a controllable range, that is sufficient. The corrosion rate can be calculated. For the calculation method, refer to GB/T 18175-2004 \"Testing of corrosion inhibition performance of water treatment chemicals – Rotating disk method\"; this standard provides a method for calculating the corrosion rate. Carbon steel: Corrosion rate less than 0.075 mm/year. Stainless steel: Corrosion rate less than 0.005 mm/year
Water can also cause corrosion in carbon steel (up to 0.15 MM/Y—according to the data at hand). It is necessary to take into account corrosion caused by cooling water, as well as factors such as water flow rate, sedimentation, and microorganisms...
There will be a major overhaul in a while, and the answer will be revealed soon
1. Using circulating water in the shell side is not the optimal process choice. Generally, water is used in the tube side of the system; corrosion by circulating water is inevitable. Therefore, when selecting the process layout, priority is given to minimizing the likelihood and rate of corrosion ； 2. Carbon steel pipe bundles in circulating water systems require anti-corrosion treatment (there are various methods) ； 3. The circulating water must be treated with chemicals to keep parameters such as turbidity, conductivity, and biological sludge under control.
This applies to all of them: refining, coal-to-oil, and coal-to-hydrocarbons. As long as it is not a fixed-tube-plate type water cooler, applying EFT anti-corrosion coating to the shell side is sufficient. Sinopec, CNPC, Sinochem, CNOOC (Huizhou) are all engaged in this activity. Meanwhile, the large-type casing (with floating heads that serve as sacrificial anodes, along with AL-Zn-In-Cd cathodic protection) offers good toughness at room temperature, lacks brittleness, and features an anti-corrosion coating that provides a longer service life.