1.Why not recommended?
High risk of chemical corrosion:
Coating failure: Chemical waste gas often contains acid mist (such as SO₂, HCl, NOx), alkali mist (such as NH₃), organic solvent vapor (such as benzene, esters, ketones), etc. These chemicals will penetrate, swell, and decompose the organic coating of the color-coated board, causing the coating to bubble, fall off, and lose its protective effect.
Rapid corrosion of the substrate: Once the coating is damaged, the internal galvanized layer or aluminum layer will be directly exposed to corrosive gases or condensate. In a chemical environment, the corrosion resistance of the galvanized layer is far from enough, which will cause the substrate to quickly rust and perforate, causing equipment leakage.
Temperature and condensate issues:
The temperature may change during the waste gas treatment process, and condensation may easily occur. Condensate is a concentrated liquid of corrosive substances. It is extremely corrosive and will accumulate at the bottom or wall of the equipment, causing long-term and fatal immersion corrosion of materials. Color-coated boards are completely unbearable.
Poor mechanical and wear resistance:
The equipment may be bumped during installation, operation, and maintenance. Once the paint coating is scratched, corrosion will spread from the scratch.
2.What are the possible, extremely limited applicable scenarios?
High-quality color-coated rolls (such as thick coatings, PVDF topcoats) can only be considered if all of the following conditions are met:
The treated exhaust gas is absolutely clean: only normal temperature, non-corrosive, and chemical-free particulate matter is removed (such as simple wood processing dust, grain dust), and it is ensured that the exhaust gas does not contain any acidic gases, organic solvents, etc.
Absolutely dry: There is no possibility of condensation in the process, and the humidity of the exhaust gas is low.
The device is located indoors or in a well-shielded environment and is not affected by external rain or ultraviolet rays.
Used as an external protective panel for equipment: only as a non-load-bearing, non-sealed external decoration or protective cover, not in contact with exhaust gas. But even so, attention should be paid to the corrosive gases that may disperse in the workshop and corrode its exterior.
3.What are the recommended materials for chemical waste gas treatment equipment?
Fiberglass Reinforced Plastic (FRP): A very common and cost-effective option. Excellent acid and alkali corrosion resistance, light weight, easy to process and shape. Applicable to most acid and alkaline waste gas wet treatment equipment.
Stainless steel:
304 stainless steel: suitable for general weak corrosion environments.
316L stainless steel: Molybdenum element enhances the corrosion resistance of chloride ions and is suitable for exhaust gas containing chloride ions (such as HCl).
Duplex Stainless Steel: More corrosion resistant and stronger, used in more severe environments.
Carbon steel lined with anti-corrosion layer:
Rubber lining, plastic lining (PP/PE/PO): Provides excellent chemical corrosion resistance barrier.
Coating with heavy anti-corrosion coatings: such as epoxy resin, glass flake coating, etc., requires strict surface treatment and professional construction.
Plastic (PP/PVC/FRPP): Plastics such as polypropylene have good acid and alkali resistance and are often used in small equipment or as linings.
Special alloys: used in extreme working conditions such as high temperature and high corrosion, but the cost is extremely high.
4.What are the core principles?
"Chemical anti-corrosion, safety first." Material selection should be based on detailed exhaust gas composition analysis reports and operating conditions.
5.Any suggestions?
For the main structure of chemical waste gas treatment equipment (the part in direct contact with waste gas), the use of color-coated rolls should be avoided. Its initial cost savings are far from making up for the maintenance, production shutdown and safety risks caused by its premature failure.
The right thing to do: Consult a professional environmental equipment engineer or materials engineer to conduct a detailed corrosion assessment and choose among proven materials such as FRP, stainless steel, plastic-lined carbon steel, etc.