What coating provides the best corrosion protection for gasoline cooler tubes?

For heat exchanger tube bundles, aluminum serves as an anti-corrosion coating that indeed prevents corrosion of the carbon steel surface on the oil and gas side. Thermal spraying of aluminum cannot be used for coating the surface of heat exchangers, but hot-dip aluminum coating is available.

Firstly, the tube bundle is made of carbon steel; stainless steel cannot be used for corrosion protection due to its very poor adhesion. If it is on the side involving circulating water, coating protection can be considered; SHY99 or TH847 are commonly used in the market. The key factor here is the manufacturer of the anti-corrosion coatings. There are many critical aspects that need to be taken into account when using such coatings. If the company performing the anti-corrosion treatment is unqualified, it can lead to issues such as incomplete surface treatment, residual acid not being removed properly, inadequate sandblasting, missed areas during coating application, pinholes, sagging, drooping, incomplete curing at high temperatures, and the use of coatings whose warranty period has expired. At the same time, the coating itself may contain oxides; for example, whether the primer contains iron oxide red. And whether the coating is resistant to steam purging, along with the specific data. Generally, the coating thickness should be no less than 120 microns; if it is on the side exposed to materials, the temperature and the main corrosive agents need to be taken into account. For low temperatures and environments free of oxidizing acids, SHY99 and TH901 can be considered; however, with TH901, it is necessary to use paint that is still within its warranty period, as the warranty duration is short. Generally, anti-corrosion companies use paint that has passed its expiration date. TH901 is quite brittle and not suitable for long-distance transportation, as even minor impacts can cause the coating to peel off. If the temperature on one side of the material is high but not above 200 degrees, and the corrosive environment is not complex nor are the operating conditions severe, then a Ni-P coating can be considered; however, the nickel-phosphorus coating must be applied to newly manufactured carbon steel tube bundles. The typical coating thickness is 50 microns; for higher requirements, it is 70–75 microns. However, this results in higher costs, but it does increase the service life significantly and makes the material more durable than ordinary stainless steel. For paint selection, SHY99 is recommended. If 304, 304L, or 316L stainless steel is chosen, consideration must be given to chloride corrosion and intergranular corrosion, as well as attention should be paid to welding at the pipe ends. Please forgive any shortcomings in the above answers.