Selection reference
Choose a corrosion protection coating by substrate and exposure
Corrosion protection is a system: surface preparation, a primer or inhibitor, the barrier or galvanic coating and a proper cure. Start with the substrate and the exposure, then confirm the specified standard, dry film thickness, recoat window and return to service.
| Application or product type | What to confirm | Standards and approvals commonly specified |
|---|---|---|
| Galvanizing repair and zinc-rich protection for steel | Damaged hot-dip galvanizing, weld seams, cut edges, fasteners and bare structural steel. Confirm ASTM A780 or the specified repair method, surface cleanliness, dry film thickness and whether the zinc stays exposed or takes a topcoat. Zinc-rich films protect galvanically, so performance depends on zinc loading and metal-to-metal contact. | ASTM A780 galvanizing repair; SSPC-Paint 20 zinc-rich primer; ASTM D520 zinc dust type; ASTM B117 salt-spray exposure; UL recognition where the specification requires it. |
| Weather- and chemical-resistant finishes for metal | Equipment, railings, frames, food-plant and washdown areas, exterior steel. Confirm primer compatibility, UV and immersion exposure, incidental food-contact or sanitary requirements and the recoat window. A single-component polyurethane simplifies field touch-up; a two-component epoxy system adds film build for harsher service. | SSPC-SP surface preparation grades; specified dry film thickness; ASTM D4541 pull-off adhesion; ASTM B117 salt spray or QUV weathering data; USDA or FDA incidental food-contact acceptance where required. |
| Corrosion inhibition for reinforced concrete | Parking structures, bridges, marine and coastal concrete, chloride- or carbonation-affected slabs. Confirm the condition survey, cover depth, application rate and number of coats, and compatibility with the repair mortar or protective coating that follows. Penetrating inhibitors treat embedded steel through the concrete; bonding-agent coatings protect exposed bars inside a patch repair. | ACI 562 repair code and ICRI guidelines; ASTM C876 half-cell survey and chloride or carbonation testing from the condition assessment; manufacturer application rate and compatibility statement for the following repair system. |
| Chemical-resistant epoxy and novolac coatings and linings | Secondary containment, trenches, sumps, tank and silo linings, process floors and steel in chemical service. Confirm the chemical, concentration, temperature and duration of exposure against the manufacturer’s resistance chart, plus substrate moisture, primer and minimum concrete age. Novolac epoxies extend resistance to concentrated acids and solvents; standard epoxies suit general chemical and abrasion service. | ICRI 310.2R concrete surface profile; ASTM D7234 or ASTM C1583 bond strength; manufacturer chemical resistance chart for the listed reagents and concentrations; NSF/ANSI 61 where the lining contacts potable water. |
| Pipe and metal repair | Leaking or corroded pipe, cast-iron drain lines, tanks and worn metal parts. Confirm pipe diameter and material, whether the leak is live, operating pressure and temperature, and any potable-water requirement. Epoxy putty seals an isolated leak; self-fusing tape seals a live leak; the water-activated bandage reinforces either into a permanent repair. | ASME PCC-2 Article 4.1 or ISO 24817 for engineered composite pipe repairs; rated pressure and temperature of the repair method; NSF/ANSI 61 or WRAS listing for potable water; owner permit and documentation requirements. |
Published resistance, film build and cure values apply only at the stated dry film thickness, temperature and surface preparation. Use the current product datasheet and chemical resistance chart before approving a substitution. This category also lists concrete curing, sealing and densifying products; see Concrete Curing and Sealing for their selection notes.
Field planning
Plan the corrosion protection application
Most coating failures trace to preparation, film build or cure rather than to the product. Use the manufacturer instructions with the project specification and record the conditions at each stage.
Surface preparation controls the result
Steel needs the cleanliness and anchor profile the datasheet calls for, whether that is hand-tool cleaning for a zinc-rich touch-up or abrasive blasting for an epoxy lining. Remove oil, salts and loose rust, then coat before the surface re-rusts.
Concrete needs laitance removed, an open textured profile, adequate pull-off strength and moisture within the product limit. Verify minimum concrete age before applying epoxy or novolac systems.
Film build, recoat window and cure
Specify and measure dry film thickness; check wet film during application so each coat lands within range. Note the recoat window for every product, because a missed window usually means additional preparation before the next coat.
Temperature, humidity and substrate temperature change pot life, cure and return to service. Immersion and chemical service normally require a longer cure than foot traffic.
Galvanic protection versus barrier protection
Zinc-rich compounds protect steel sacrificially and tolerate small breaks in the film. Epoxy and polyurethane coatings protect as a barrier, so continuity, thickness and edge coverage decide their service life. Many systems combine a zinc-rich or epoxy primer with a topcoat.
Penetrating corrosion inhibitors work differently again: they migrate through hardened concrete to the reinforcing steel and are usually followed by a repair mortar or protective coating.
Live leaks and emergency repair
Isolate the line where possible and clean and roughen the pipe. Choose the kit by pipe diameter and material, and confirm the rated pressure and temperature for the sealing method used. Where flow cannot be stopped, a self-fusing tape seals the live leak before the bandage reinforces it.
Repairs to potable-water lines need a product approved for that service. Document the repair for the maintenance record and schedule replacement where the specification requires it.
Before you order
Corrosion protection coating specifications & quantity planning
Use the project specification and the selected manufacturer data to confirm performance, coverage and the documents required for the installation.
Compare the specified performance
Read the specified standard, dry film thickness, chemical resistance, service temperature and adhesion values together with their test methods. Confirm VOC limits for the jurisdiction and any potable-water, food-contact or UL requirement before selecting a product.
Calculate coverage and kits
Start with the theoretical spreading rate at the specified dry film thickness, add a loss factor for spray, surface profile and porosity, and multiply by the number of coats. Two-component products are sold in fixed kits with fixed mix ratios, so round up to whole kits and plan pot life around crew size.
Assemble the submittal
Identify the manufacturer, product, color, package size and SKU. Gather the current product datasheet, SDS, chemical resistance chart, application guide and any certification requested, such as NSF/ANSI 61, UL recognition or USDA acceptance. Ask for technical help when a document or limit is unclear.
Project orders
Request corrosion protection project pricing
Send the specified coating, primer or repair kits and quantities for your project, shutdown or maintenance program. If the product is still under review, include the specification, substrate and exposure details.
Include with your request
- Manufacturer, product, color and package size
- Square footage and coats, or pipe diameters and number of repairs
- Substrate, exposure and planned surface preparation
- Delivery ZIP and required-on-site date
Corrosion protection coating questions
What is a corrosion protection coating?
It is a coating system applied to steel, concrete or other substrates to slow corrosion by isolating the surface from moisture, oxygen, chlorides and chemicals, by protecting the metal galvanically with zinc, or by inhibiting the corrosion reaction at embedded reinforcing steel. The product type, surface preparation and film thickness together determine how long the protection lasts.
Does cold galvanizing compound replace hot-dip galvanizing?
Zinc-rich cold galvanizing compounds are the recognized method for repairing damaged hot-dip galvanizing under ASTM A780 and are widely used on weld seams, cut edges and field-erected steel. Whether a compound may stand in for hot-dip galvanizing on a given project depends on the specification and the exposure, so confirm with the specifier and the product datasheet.
Can I coat rusted steel without abrasive blasting?
Some products are published for hand- or power-tool cleaned steel, while epoxy linings and immersion service usually require abrasive blasting to a specified cleanliness and profile. Follow the surface preparation in the datasheet for the product and the service; loose rust, mill scale, oil and salts must be removed in every case.
How do I protect reinforcing steel in existing concrete?
Surface-applied penetrating corrosion inhibitors migrate through hardened concrete to the reinforcing steel and are used on structures affected by chlorides or carbonation without removing sound concrete. In a patch repair, exposed bars are cleaned and coated with a bonding-agent corrosion protection product before the repair mortar is placed. Both are normally part of a larger repair and protection system.
What is the difference between an epoxy coating and a novolac epoxy?
Standard epoxy coatings provide a hard, chemical- and abrasion-resistant barrier for floors, walls, tanks and steel in general service. Novolac epoxies use a modified resin that extends resistance to concentrated acids, solvents and higher temperatures, which is why they are specified for secondary containment, sumps and aggressive process areas. Always check the specific chemical against the manufacturer’s resistance chart.
Can I repair a leaking pipe without shutting it off?
Yes, within the rated limits of the products. Live-leak kits use a self-fusing tape that seals under flow, followed by a water-activated fiberglass bandage that sets to a rigid, impact-resistant shell. Where the line can be isolated, an epoxy putty seals the hole or crack before the bandage is applied. Confirm the pipe diameter, material, pressure, temperature and any potable-water requirement before ordering.
How much coating do I need?
Divide the surface area by the product’s theoretical coverage at the specified dry film thickness, add a loss factor for spray, profile and porosity, then multiply by the number of coats and round up to whole units or kits. Two-component products cannot be split from the kit ratio, and aerosols are priced for touch-up rather than large areas.
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