The cheapest corrosion coating quote is rarely the cheapest way to protect steel. To compare quotes properly, add up surface preparation, access, number of coats, downtime and how many times you will repaint over the life of the asset, then divide by the years of protection you get. A single coat, surface tolerant system that lasts more than 20 years can cost more per litre and still work out far cheaper per year.
This article is written for the person who has to choose between two or three coating quotes: the procurement officer, the maintenance planner, or the engineer who signs off the job. It sets out what to look at, what to ask, and where a silicone corrosion maintenance coating changes the sums.
Why price per litre is the wrong place to start
Most coating quotes land on a procurement desk as a few lines. Product, litres, rand per litre, labour. The natural move is to line them up and pick the lowest.
That works for consumables. It does not work for corrosion protection. On a maintenance job the paint is usually a small part of the bill. On retrofit work, surface preparation often costs more than the coating itself. Access and downtime can cost more again.
The bigger factor is time. A system that needs repainting every five to seven years must be bought, prepared, scaffolded and applied again. Over the life of a structure, that can happen two or three times.
So the useful question is not what the job costs. It is what the protection costs per year.
What actually goes into the cost of a corrosion coating job
When we work through a maintenance job with a client, the same cost lines come up every time. Most of them never appear in the price per litre.
Surface preparation. Conventional epoxy systems are normally specified over abrasive blasted steel, usually to Sa2.5. Blasting brings compressors, abrasive, containment, cleanup and disposal of spent grit and old paint. On a running plant it also means stopping other work around the area.
Access. Scaffolding and rope access are hired by time. Every extra day spent waiting for a coat to cure is another day of hire.
Number of coats. A typical three coat system means three application passes. Each coat needs its own cure time before the next one goes on, and each coat needs checking.
Downtime. If an area has to be isolated or shut down, the cost of lost production can be larger than every other line on the quote combined. Your production team will know this number. The coating contractor will not.
Rework and inspection. More coats means more film build checks and more chances for a defect between layers.
Repaint frequency. This is the line that multiplies all the others. Every maintenance cycle repeats the preparation, access, labour and downtime costs.
How often will you repaint? The number that decides total cost of ownership
In aggressive coastal, chemical and mining environments, conventional epoxy and polyurethane systems typically need recoating every five to seven years. On a 20 year view, that is two or three full maintenance cycles on top of the original job.
SI-COAT 579 CM has a documented service life of more than 20 years in those same environments. In practical terms, one job replaces three or four.
Think about what that means on a Durban or Richards Bay site. Salt laden air, high humidity and heat break conventional systems down fast. The structure keeps needing attention, and every visit brings back the scaffolding, the shutdown planning and the permits. A longer interval between maintenance cycles is where most of the saving sits.
How to compare two corrosion coating quotes side by side
Put each quote on one sheet and answer the same questions for both. If a contractor cannot answer them, that tells you something too.
| What to check | Conventional three coat epoxy system | SI-COAT 579 CM |
|---|---|---|
| Surface preparation | Abrasive blast, usually Sa2.5 | Hand or power tool cleaning to St2 or St3 |
| Coats | Primer, intermediate and topcoat | One coat, no primer in C3 and C4 environments |
| Film build | Varies by system | 9 to 14 mils DFT in a single coat |
| Application time | Baseline | 70 to 80% less than a three coat epoxy system |
| Typical interval to recoat in harsh conditions | Five to seven years | More than 20 years documented |
Then work out the cost per year. Take the cost of the first job, add the cost of every repaint you expect within your planning period, and divide by the number of years. Include access, preparation and downtime in every cycle, not only the first.
Use the same planning period for both quotes. Twenty years is a sensible figure for most plant structures. If the asset will be in service longer, use the longer number. It only widens the gap.
Where a silicone corrosion maintenance coating changes the numbers
SI-COAT 579 CM is a single component, moisture cure RTV silicone made by CSL Silicones. It was designed for maintenance work on steel that is already corroding, in conditions where full blasting is impractical.
Three things change the cost picture.
First, preparation. It bonds to steel cleaned with hand or power tools to St2 or St3. On most maintenance jobs that removes abrasive blasting, containment and grit disposal from the quote.
Second, application. It goes on in one coat, by brush, roller or airless spray. CSL’s figures show a 70 to 80% saving in application time against a three coat epoxy system. Fewer days on site means fewer days of scaffold hire and a shorter shutdown window.
Third, life. A service life of more than 20 years means far fewer maintenance cycles over the life of the asset.
The product is not always the cheapest per litre. That is not the number to judge it on.
What the field results show
The strongest evidence on cost comes from utilities that tracked their projects closely.
Florida Power and Light ran a three year coastal fence test at Melbourne Beach, Florida, using a NASA test methodology. SI-COAT 579 outperformed 28 other coatings. The utility then used it on a 279 ft (about 85 m) fuel oil storage tank. The project cost about half of a conventional coating system, with an expected service life of more than 30 years against 15 years for the conventional option.
Reliant Energy used it on 8,000 transmission towers around Galveston Bay in Texas, in tidal saltwater conditions. Project timelines dropped from four months to six weeks. Worker health complaints linked to epoxy mastics stopped, and the towers were still in like new condition after more than 36 months.
In Morocco, the applicator Net Elec reported five years of protection on national grid pylons and concrete posts, with cost and time savings compared with the conventional sandblast, primer and finish system it replaced.
Closer to home, TSS has applied the coating at a fertiliser plant in Hoopstad, a chlorine plant in Johannesburg and on a hopper in Durban Harbour. You can read more projects on our case studies page.
Where SI-COAT 579 CM is the wrong choice
A total cost comparison only works if the coating suits the job. There are places where 579 CM will raise your cost, not lower it.
It is not suitable for continuous liquid immersion. Tank internals, submerged pipework and similar areas need an immersion rated system to ISO 12944 part 9.
It is a flexible silicone, so it is soft compared with an epoxy. It is not the right choice for walkways, chutes, impact zones or anywhere that sees abrasion and wear.
In the most severe C5 environments, it goes over a zinc phosphate epoxy primer. That adds a step, so price it into the comparison.
If a supplier tells you one coating suits every surface on your plant, be cautious. Good specifications mix systems according to exposure.
Questions to ask before you approve a corrosion coating quote
What surface preparation standard does this system need, and can we actually achieve it on site? How many coats, and how long between them? How many days on site in total, and how many of those need a shutdown or isolation? What service life should we expect in our environment, not in a brochure? Has this system been used in conditions like ours, and can we see the results?
If you want help putting two quotes side by side for a specific structure, send us the details and we will work through it with you.
Frequently asked questions
How much does corrosion protection coating cost in South Africa?
It depends on the area, access, surface condition and environment. We do not quote a single rand per square metre figure, because preparation, access and downtime often outweigh the product cost. Ask for a quote that breaks out each of these lines, then compare cost per year of protection.
Is a more expensive coating worth it if it lasts longer?
Often, yes. If a coating costs more upfront but removes two or three repaint cycles over 20 years, the total cost of ownership is usually lower. Run the cost per year calculation with your own access and downtime figures to check.
Do I need to sandblast before applying SI-COAT 579 CM?
No, not in most cases. It bonds to steel cleaned by hand or power tools to St2 or St3. In the most severe C5 environments it is applied over a zinc phosphate epoxy primer. More detail is in the SI-COAT 579 CM FAQ.
How long does SI-COAT 579 CM last?
It has a documented service life of more than 20 years in environments where conventional epoxy and polyurethane systems typically fail in five to seven years. On the Florida Power and Light tank project, the expected service life was more than 30 years.
Can SI-COAT 579 CM be used inside tanks or under water?
No. It is not suitable for continuous liquid immersion. Use an immersion rated system for tank internals and submerged steel.
How do I calculate total cost of ownership for a coating system?
Add the cost of the first application to the cost of every repaint you expect over your planning period. Include preparation, access, labour and downtime each time. Divide the total by the number of years in the period.
Proud exclusive distributor of CSL Silicones in Southern Africa.