About STP ShaliProtek PU HG

ShaliProtek PU HG from STP Limited is a purpose-built lining system rather than a general-purpose paint. It is a two-component, solvent-free polyurethane that cures at 100% volume solids, meaning virtually the entire film you spray stays on the substrate with no shrinkage from evaporating solvent and no VOC release. The system is applied as a base coat followed by a high-gloss top coat, and it is engineered specifically for the internal faces of concrete and steel structures where abrasion, impact and aggressive chemistry would quickly destroy an ordinary coating. Its original design brief was the inside of mineral-powder storage silos, where free-flowing dry solids constantly scour the walls, so wear resistance and a low coefficient of friction were non-negotiable requirements.

That silo pedigree is why the same product has migrated into so many other punishing environments. Because it resists sea water, most acids and alkalis, and microbiologically induced corrosion, it is specified inside sewage treatment plant tanks, reservoirs, cooling tower basins, hydro-electric penstocks and dam gates, and on marine and offshore steelwork including ship decks and hulls. It is also used to line pipelines carrying potable and waste water, both in the factory and for on-site repair and re-coating of existing lines. In every case the value is the same: a monolithic, high-build, spray-applied film that seals the substrate, shrugs off mechanical punishment and buys the asset owner years of extra service life.

The technical insight

The performance comes from combining a 100% solid two-component chemistry with plural-component airless spray application. Because there is no solvent to flash off, the coating can be built to a heavy 1000 micron dry film thickness in a single pass without the pinholing, sagging or trapped-solvent blistering that plague thinner systems, and the coating shows no sag on vertical silo walls. The 3:1 base-to-hardener ratio is metered and mixed at the spray tip, so the very short 10 to 20 minute pot life never becomes a handling problem, and Part A is pre-heated to keep viscosity low enough for clean atomisation at 2500 to 4000 psi. Once cured, the polymer network reaches Shore D 60 hardness, which is what produces the sub-40 mg Taber abrasion loss (H-10 wheel, 1000 g, 1000 cycles) and 86 kg/cm impact resistance that let it survive scouring solids and dropped tools. The dense, cross-linked film also delivers adhesion above 10 MPa on blasted steel, so the coating fails cohesively in the substrate rather than peeling, and its low permeability blocks the moisture path that microbially induced and sea-water corrosion depend on.

Where it is used

• Internal lining of mineral-powder storage silos and hoppers where dry solids continuously abrade the walls
• Sewage treatment plant tanks, reservoirs and secondary containment where chemical and biological attack is severe
• Potable-water and waste-water pipeline linings, applied in-plant or for on-site re-coating and repair
• Cooling tower basins and internal surfaces in thermal power plants
• Hydro-electric penstocks, dam gates and other high-flow hydraulic steelwork
• Marine and offshore structures, marine piles, ship decks and ship hulls exposed to sea water
• Storage tanks, mounded bullets and process vessels needing an abrasion- and chemical-resistant lining
• Coatings for pipes used in bore or directional-drilling applications and concrete tunnels

Key advantages

• 100% solid, solvent-free and VOC-free, so almost the full wet film is retained and confined-space application is far safer
• Very high abrasion resistance with Taber loss under 40 mg, ideal for scouring dry-solids and high-flow water service
• Excellent adhesion, exceeding 10 MPa on steel and 3 MPa on concrete, so the film bonds tighter than the substrate’s own strength
• Excellent resistance to sea water and to most acids and alkalis, plus protection against microbiologically induced corrosion
• Fast curing, touch dry in under an hour and ready to overcoat in 4 to 6 hours, shortening plant downtime
• High-build in a single application, achieving 1000 micron DFT with no sag on vertical surfaces
• Hard, high-gloss (75 to 80 percent) finish that is easy to clean and inspect and resists scratching
• Certified suitable for potable-water pipeline and waste-water applications

Limitations & considerations

• Requires plural-component airless spray equipment with heated lines, so it is not a brush- or roller-applied product for small jobs
• Very short pot life of 10 to 20 minutes at 30 C means it must be machine-metered and cannot be hand-mixed in bulk
• Aromatic PU chemistry means it is optimised for internal and immersed surfaces; UV-exposed external surfaces need an aliphatic PU top coat for colour and gloss retention
• Application demands a properly prepared substrate, SA2.5 blast on steel and honeycomb repair with PMC mortar on concrete, with substrate moisture below 5 percent
• Ambient and substrate temperature and humidity windows are tight (5 to 50 C ambient, up to 65 percent RH), so site conditions must be controlled
• Supplied only in 200 L drum sets, which suits large industrial contracts rather than small patch repairs

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliProtek PU HG

ShaliProtek PU HG is Space Arc’s go-to STP lining for high-abrasion, immersed and internal steel or concrete service. Within the STP polyurethane family, pair it with ShaliProtek PU HA, a water-based, UV-resistant elastomeric PU top coat, where an external or sun-exposed surface needs weatherability; consider ShaliUrethane LHM Plus or LHM 2K when the requirement shifts from a hard lining to a flexible, crack-bridging waterproofing membrane; and use ShaliPrime 2PU or STP Thinner as the companion primer and flushing solvent for the system. For interiors of drinking-water tanks or where a hybrid chemistry is preferred, our Fosroc range offers a genuine alternative, and we also stock Sika and Dr. Fixit protective coatings when a project’s approved-vendor list calls for a specific brand.

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