CORROSION MAINTENANCE

SI-COAT 579 CM Corrosion Maintenance Coating for Structural Steel and Industrial Infrastructure

SI-COAT 579 CM is a single component moisture cure RTV silicone corrosion maintenance coating manufactured by CSL Silicones and distributed exclusively across Sub-Saharan Africa by Technical Solutions Supplies. It protects structural steel, storage tanks, bridges, mining infrastructure, industrial equipment and pipelines from corrosion in the harshest outdoor environments across Southern Africa and beyond.

It was specifically formulated as a surface tolerant coating for maintenance projects where abrasive blast cleaning to Sa2.5 is not achievable. It bonds directly to steel prepared by hand tool or power tool cleaning to St2 or St3 standard under ISO 8501-1, applies in a single coat without primer, and delivers a service life exceeding 20 years in environments that destroy conventional epoxy and polyurethane coatings within five to seven years.

The Surface Preparation Problem That Conventional Coatings Cannot Solve

Most high performance corrosion protection systems specify abrasive blast cleaning to Sa2.5 near white metal as their minimum surface preparation requirement. On new build projects in a fabrication workshop this is achievable. On in-service maintenance projects it frequently is not.

Access to bridge steelwork is constrained and expensive. Traffic management during bridge maintenance carries significant operational and financial burden. Abrasive blasting on an active road structure generates dust and debris that creates safety, environmental and regulatory complications. Storage tanks on operational mining sites cannot be taken offline for full blast and recoat programmes. Industrial structures in chemical plants cannot accommodate blast cleaning containment without production shutdowns.

The result is that conventional corrosion maintenance on these structures gets deferred repeatedly until failure is visible and urgent. By that point the steel has corroded significantly and the consequential cost of repair far exceeds what a proactive maintenance programme would have cost.

SI-COAT 579 CM was designed specifically for this reality. Standard maintenance crews with standard equipment can achieve St2 or St3 preparation in operational maintenance windows. That is what makes effective corrosion protection achievable on the structures that matter most.

Key Performance Properties

Surface tolerant performance is the defining property of SI-COAT 579 CM. It bonds to steel prepared to St2 or St3 standard under ISO 8501-1 without abrasive blasting. Wire brushes, angle grinders, disc sanders and needle guns meet the surface preparation requirement. Maintenance that was previously deferred because blast cleaning was impractical becomes achievable with normal maintenance resources.

Single coat system means one application provides both corrosion protection and a UV stable finished surface. No zinc rich primer, no epoxy intermediate coat, no polyurethane topcoat. The difference between one coat and three is often the difference between a maintenance project that gets done and one that gets deferred indefinitely.

Permanent flexibility as a silicone elastomer means 579 CM accommodates the micro-movement, vibration and thermal cycling that characterise in-service steel structures. Rigid coatings develop hairline cracks under this movement, allowing moisture to penetrate beneath the film where corrosion proceeds hidden from view. SI-COAT 579 CM does not crack.

Permanent UV stability means the silicon oxygen polymer backbone does not degrade under UV radiation. SI-COAT 579 CM does not chalk, yellow, crack or lose flexibility under any UV exposure level. This matters greatly in Southern Africa where UV radiation levels accelerate the degradation of conventional coatings significantly beyond temperate climate data sheet predictions.

Chemical resistance covers sulphuric acid, alkalis, chlorides and the full range of industrial contaminants encountered in mining, chemical processing, petrochemical and coastal environments.

Service life exceeds 20 years on correctly prepared steel in harsh outdoor conditions. Epoxy systems in the same environments require recoating every five to seven years. Over a 20 year asset life, silicone delivers total lifecycle costs 40 to 60% lower than conventional systems when all recoating, labour, access and downtime costs are included.

Where SI-COAT 579 CM Is Used

Bridges and overpasses across South Africa’s road network face a growing maintenance backlog. SI-COAT 579 CM applies to bridge steelwork during planned maintenance shutdowns without blast cleaning, making proactive corrosion maintenance financially and operationally viable rather than repeatedly deferred.

Mining infrastructure across the Copperbelt in Zambia and the DRC, South African gold and platinum operations, and Namibian coastal mining facilities all face extreme corrosion conditions from sulphuric acid, chloride attack and industrial contamination. SI-COAT 579 CM resists these environments and applies to in-service equipment without blast cleaning logistics that operational mining cannot accommodate.

Storage tanks on mining sites, petrochemical facilities and chemical plants face chemical splash, UV exposure and thermal cycling that accelerate conventional coating failure. 579 CM applies during operational maintenance windows without production shutdown requirements.

Coastal industrial structures in KwaZulu-Natal, the Western Cape, coastal Namibia and Mozambique face aggressive chloride attack combined with high UV radiation. Silicone chemistry is not subject to chloride induced degradation or UV driven photodegradation.

Corrosivity Classification Under ISO 12944

Applied directly to St2 or St3 prepared steel without primer, SI-COAT 579 CM provides corrosion resistance suitable for C3 and C4 corrosivity categories per ISO 12944. Applied over a zinc phosphate epoxy primer to correctly prepared steel, it achieves C5-M marine and C5-I industrial corrosion protection per ISO 12944-6, the most stringent international standard for aggressive marine and industrial environments.

Application Summary

Substrate: structural steel, carbon steel, weathering steel, galvanised steel, concrete, previously coated surfaces where existing coating is sound. Surface preparation: hand tool or power tool clean to St2 or St3 under ISO 8501-1, no abrasive blasting required. Application method: brush, roller or airless spray. System: single coat, no primer or topcoat required for C3 and C4 environments. Cure: moisture cure RTV at ambient temperature and humidity. Temperature range: below zero to above 200 degrees Celsius. Service life: 20 or more years in harsh outdoor environments. ISO 12944 classification: C3 and C4 direct to St2 and St3 steel, C5-M and C5-I over zinc phosphate epoxy primer.

SI-COAT 579 CM vs Conventional Corrosion Coatings

Epoxy systems require Sa2.5 blast cleaning, carry a service life of 5 to 7 years outdoors, degrade under UV exposure, crack under thermal cycling and require a primer and topcoat system.

Polyurethane systems require Sa2.5 blast cleaning, carry a service life of 5 to 8 years outdoors, yellow and degrade under UV, require primer and are moisture sensitive during application.

SI-COAT 579 CM bonds to St2 and St3 prepared steel, delivers a service life exceeding 20 years, provides permanent UV stability and flexibility, applies in a single coat without primer and achieves C5 classification over zinc phosphate primer.

For full technical specifications and application guidelines, download the Technical Data Sheet below or contact Technical Solutions Supplies directly.

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Phone: 031 002 7376 Email: sales@tssupplies.co.za

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