Questions regarding the anti-corrosion primer for stainless steel equipment

316L doesn’t require an anti-corrosion primer, right? 100-degree epoxy zinc-rich coating should be fine. Is the customer considering painting to meet the aesthetic requirements of the site? In that case, just applying the topcoat will be sufficient.

It’s not about aesthetics; it’s mainly about acid resistance. I want to know whether organic zinc-rich primers are acid-resistant; someone please let me know, I’m waiting for a reply urgently

Oh, are you talking about coating the inner surface of the container with anti-corrosion paint?

Introduction to Epoxy Zinc-rich Primer I. Composition: A two-component primer made up of epoxy resin, zinc powder, solvents, and amine-based curing agents. II. Characteristics: Excellent corrosion resistance, strong adhesion, high zinc powder content in the paint film, and outstanding water resistance. 　　III. Applications: Used as a base coat to complement heavy-duty anti-corrosion coatings, for applications on ships, port facilities, bridges, steel structures, oil drilling platforms, and chemical processing equipment. 　　IV. Technical requirements: HG/T3668-2000 Item Specifications Color and appearance: Gray, with variable shade; paint film should be smooth Viscosity, S (Cast-4 cup): ≥ 20 Drying time, h: ≤ Surface dry time: 1 ； Practical performance: 24 Impact strength, kg·cm ≥ 50 Flexibility, mm: 1 Saltwater resistance: passes after 72 hours V. Construction guidelines 1. The surface of the object to be coated must be free of oxide scale, rust, oil stains, etc. 　　2. The substrate temperature must be at least 3°C above the dew point; when the substrate temperature is below 5°C, the paint film will not cure, so painting should not be carried out under such conditions. 　　3. After opening the container of Component A, it must be mixed thoroughly. Then, Component B should be added to Component A while stirring, in accordance with the specified ratio, and the mixture should be mixed well again. After allowing it to stand and mature for 30 minutes, an appropriate amount of diluent should be added to achieve the desired viscosity for application. 　　4. Use the paint mixture within 6 hours after mixing. 　　5. Brush coating, air spraying, and roller coating are all acceptable. 　　6. Continuous stirring is necessary during the coating process to prevent precipitation. 　　7. Painting interval: Base material temperature (°C): 5-10, 15-20, 25-30. Minimum interval (hours): 48, 24, 12. The maximum interval shall not exceed 7 days. 　　8. Recommended film thickness: 60–80 um. 　　VI. Transportation and Storage 　　1. During transportation, the product should be protected from rain and direct sunlight, as well as from collisions, and must comply with the relevant regulations set by transportation authorities. 　　2. The products should be stored in a cool and well-ventilated area, away from direct sunlight, and in a warehouse that is free from sources of fire and heat. 　　VII. Safety Protections 　　The construction site should have adequate ventilation. Painters should wear glasses, gloves, masks, etc., to prevent skin contact and inhalation of paint fumes. Fire and smoking are strictly prohibited at the construction site. 　　Performance: It is an electrochemical protective coating. This paint offers excellent corrosion resistance, good mechanical properties, strong adhesion, as well as electrical conductivity and cathodic protection capabilities. It can be used as a pre-coating primer in workshops; with a film thickness of 15–25 um, it does not affect welding performance. This product is also often used as an anti-rust primer. 　　Purpose: It is suitable as an anti-rust primer layer for the surfaces of steel structural equipment in industries such as oil storage tanks, bridges and ships, offshore oil drilling platforms, port facilities, smelting plants, and chemical processing equipment. It can also be used as a maintenance primer after steel plate polishing or sandblasting. 　　Key technical specifications: Surface dry time ≤1 hour, full dry time ≤24 hours; Workable time ≥5 hours. Impact resistance: 50 cm·kg. Salt spray resistance: capable of withstanding salt spray for 72 hours. Safety and hygiene regulations: This product contains flammable organic solvents and is somewhat toxic. It should be stored in a cool, well-ventilated, and dry place, away from sources of fire and heat. During transportation, it should be protected from rain and exposure to sunlight. When in use, the safety regulations for painting operations as well as the relevant procedural guidelines must be followed. At the construction site, proper ventilation must be ensured, and measures such as fire prevention, static electricity prevention, and poisoning prevention should be taken.

I’m a bit confused – why use austenitic stainless steel when hydrochloric acid is present, and why add a coating for protection? I don’t understand how this was considered during the design process

First of all, using 300-series stainless steel is definitely not an option, as it contains chloride ions; at a temperature of 100°C, other materials should be chosen, such as Monel and Inconel, or linings made of PTFE or acid-resistant brick.

Using epoxy paint for corrosion protection on the inner walls of reactors is problematic; in simple terms, it wears away after a certain period of time. Ordinary acids (other than hydrochloric acid) pose no problem with 300 series stainless steel; however, in the case of hydrochloric acid, even with epoxy coating, it is not very effective.