What is the best method for preventing corrosion in a 50-meter-high carbon steel distillation tower?
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Our company is constructing a methanol project that includes three tall towers. Due to their great height, it is difficult to provide effective corrosion protection; therefore, we want to make a larger investment up front to ensure proper corrosion protection. What is the best method for protecting 50-meter-high carbon steel distillation towers from corrosion? How long does it take for the first anti-corrosion treatment, and how long before a second treatment is needed? What is the difference in investment costs compared to conventional anti-corrosion methods?
Is it the inner wall or the outer wall? I don’t know about the inner wall. For the exterior wall, if the temperature does not exceed 120 degrees, the following approach can be adopted: 1. Use sandblasting to achieve a surface finish of Sa 2.5 level; it would be better to reach Sa 3 level ； 2 Apply 1–2 coats of water-based inorganic zinc-rich paint or epoxy zinc-rich primer, with a dry film thickness of 60–80 microns ； 3 Apply 2-3 coats of epoxy limonite intermediate coat, with a dry film thickness of 150 microns to 200 microns ； 4 Apply 2 coats of acrylic polyurethane topcoat, with a dry film thickness of 80 microns. The total thickness of the coating is not less than 300 microns, ensuring a service life of over 10 years in industrial atmospheric corrosion environments. Moreover, during maintenance, it is sufficient to grind off the weathered layer on the surface, roughen it, and then apply two coats of 80-micron acrylic polyurethane topcoat, which can still extend its lifespan by 8-10 years. The specific price depends on your requirements as well as the size of the project; it is calculated based on area, and it ranges from 80 to 150 yuan per square meter.
Going up to the top – it’s already difficult to achieve a sandblasting level of 2.5 on the outside of the tower; trying to reach 3.0 is even more challenging. After all, the tower is 50 meters high, which means the cost of sandblasting will be extremely high
I’ve never heard of a new project where anti-corrosion measures are not taken first; instead, the installation is carried out first and then anti-corrosion treatment is applied. If that’s the case, it becomes quite troublesome; even if it’s made well, its lifespan is only 6-8 years.
Sandblasting for rust removal and applying the primer should be completed before installation.
Has it been lifted yet? If lifting is not used, it is recommended to carry out anti-corrosion treatment first. If lifting is used and the installation scaffolding has not been removed, things are simpler; even if it has been removed, that’s fine as well – a straight ladder can be used to reach the top of the tower. If lifting is not used, the surface needs to be sandblasted to a Sa 2.5 standard. Once lifting has been used, grinding the base surface can only be done using toothless grinding wheels. Now let’s discuss the procedures: 1. The base surface should be treated as described above. But one thing must be kept in mind: generally, purchased equipment undergoes some basic anti-corrosion treatment at the manufacturer’s facility, as a precaution against corrosion before installation. We refer to this as workshop-level anti-corrosion treatment. Usually, this kind of anti-corrosion treatment is not very effective, and in some cases no such treatment is even applied. For ordinary iron-red anti-corrosion paint, it is essential to remove this layer completely during the anti-corrosion process – remember that! Remember! Otherwise, no matter what high-quality paint you use, it won’t work! 2. The outer wall of the tower is coated with two layers of epoxy-zinc red primer and two layers of chlorinated rubber topcoat (medium gray)