STP ShaliUrethane TC
A single-component, moisture-cured aliphatic polyurethane finish coat that seals steel and pipeline protective systems with lasting UV and corrosion resistance.
What is it?
A single-component, moisture-cured aliphatic polyurethane topcoat from STP, loaded with anti-corrosive fillers and formulated for the exposed finish layer of steel and pipeline coating systems.
Where is it used?
External pipeline coatings, structural steelwork such as bridges, ballast and storage tanks, sluice gates, offshore platforms, and plant steelwork in ports, power, oil and gas, and effluent facilities.
Why use it?
It gives a glossy, colour-stable finish that survives UV, holds up in 5000-hour salt spray, tolerates flush rusting and needs no induction time, so a coating crew can top-coat without the wait a two-pack system demands.
How is it applied?
Blast-clean the steel to Sa 2½, prime with ShaliPrime MIO PU, then apply ShaliUrethane TC by airless spray, brush or roller at 50-60 microns DFT, overcoating after 10-12 hours.
About STP ShaliUrethane TC
ShaliUrethane TC sits at the top of an anti-corrosion coating stack, where it has to do two jobs at once: shrug off sunlight and weather while sealing the primer and intermediate coats beneath it against moisture and chemical attack. STP builds it as a single-component, moisture-cured aliphatic urethane, filled with a special grade of anti-corrosive pigment. Because it is aliphatic rather than aromatic, it keeps its colour and gloss under prolonged UV instead of chalking and yellowing, which is exactly what a specifier wants on a bridge, a jetty or an above-ground pipeline that will never see a repaint crew for years.
For an Indian contractor, the single-component chemistry is the practical draw. There is no base-and-hardener ratio to weigh out, no pot life ticking down on a hot afternoon, and no induction time before spraying can start; the film simply cures as it draws moisture from the air. That suits humid coastal and monsoon conditions where two-pack cures can be temperamental. It is tolerant of flush rusting on marginally prepared steel and is compatible with most existing coatings, so it also earns its place in maintenance and re-coat work, not just new fabrication. Space Arc Engineering supplies it as an authorised STP channel across Delhi NCR and Pan-India, with technical support on the full protective system.
The technical insight
The performance comes down to the resin backbone. An aliphatic urethane has no aromatic ring in the chain to absorb UV and break down, so the film resists the chalking, yellowing and gloss loss that plague cheaper aromatic PU topcoats outdoors. STP’s accelerated weathering data (ASTM D 4587) backs this up with minimal colour change and under 30 percent gloss loss at 60 degrees. Curing is driven by atmospheric moisture reacting with isocyanate groups, which is why the coat needs ambient humidity but no mixing or catalyst, and why substrate moisture must stay below 4 percent so the reaction happens in the film and not as trapped vapour under it. At 54 percent volume solids it lays down a dense barrier film; the anti-corrosive fillers plus that barrier are what carry it through 5000 hours of ASTM B 117 salt spray at 150 microns without failure, while a flexibility of over 35 percent lets the film move with steel that expands, contracts and vibrates in service.
Where it is used
- External protective topcoat on above-ground and cross-country pipelines
- Finish coat on structural steel such as bridges, gantries and walkways
- Ballast tanks, storage tanks and sluice gates in water-retaining structures
- Offshore platforms and marine steelwork exposed to salt-laden air
- Port and jetty steel infrastructure requiring long-term corrosion protection
- Plant and equipment steel in power, oil and gas installations
- Steelwork in chemical and fertiliser plants and effluent/waste-water treatment works
- Maintenance re-coating over most sound, fully cured existing coating systems
Key advantages
- Aliphatic backbone gives genuine UV and weathering stability, not the yellowing of aromatic PU
- Single component: no mixing ratios, no pot life and no induction time before spraying
- Moisture cures reliably in humid, coastal and monsoon conditions
- Passes 5000 hours of ASTM B 117 salt spray at 150 microns DFT
- High volume solids at 54 percent build a dense barrier film
- Tolerant to flush rusting and compatible with most old coatings, aiding maintenance work
- Strong abrasion and chemical resistance for industrial and marine service
- Applies by airless spray, brush or roller, so it fits both shop and site work
Limitations & considerations
- Needs ambient moisture to cure, so very dry conditions can slow film development
- A drum, once opened, must be used in full because moisture cure begins on air exposure
- Low 30°C flash point makes it flammable; keep away from ignition sources and ensure ventilation
- Substrate moisture must be under 4 percent or curing and adhesion suffer
- Best results depend on Sa 2½ blast preparation and a compatible primer such as ShaliPrime MIO PU
- Short 6-month shelf life demands disciplined stock rotation
Selection & best practice
Prepare steel by grit or shot blasting to Sa 2½ (Sa 2 minimum for general outdoor steel), removing all loose scale, oil and dirt, and confirm surface moisture is below 4 percent before any coating goes on. Prime with ShaliPrime MIO PU and let it dry, then stir the ShaliUrethane TC with a slow paddle at about 400 rpm and let entrapped air settle out before use. Apply by single-component airless spray, brush or roller to a recommended 50-60 microns dry film thickness; theoretical coverage is 10.8 m² per litre at 50 microns, so allow for spray and application losses when ordering. Respect the 10-12 hour overcoat window between coats. Touch-dry is reached in about 3 hours at 24°C and 60% RH, with full cure in around 4 days. Clean tools immediately with STP Thinner, and always finish an opened drum rather than resealing it.
Specifications
| Type | Single-component, moisture-cured aliphatic polyurethane topcoat |
| Colour / Finish | Pinkish Red or Dark Grey; glossy |
| Volume Solids (ASTM D 2369) | 54 ± 2 % |
| Density | 1.29 ± 0.02 g/cc |
| Recommended DFT | 50-60 microns |
| Theoretical Coverage | 10.8 m²/L at 50 microns DFT |
| Touch Dry / Overcoat / Full Cure | 3 hrs / 10-12 hrs / 4 days (24°C, 60% RH) |
| Salt Spray (ASTM B 117, 150µ DFT) | Pass at 5000 hours |
| Flexibility (ASTM D 522) | >35 % |
| Pack Size / Shelf Life | 20 L MS drum; 6 months unopened at 5-38°C |
Industry use cases
Pipelines & Oil and Gas
External finish coat over MIO-primed above-ground and cross-country pipelines, protecting the line from UV, corrosion and mechanical wear across long unattended runs.
Bridges & Structural Steel
Colour-stable topcoat on bridge girders, gantries and walkways where repainting access is costly and the film must hold gloss and protection for years.
Marine & Offshore
Salt-spray-proven finish for offshore platforms, jetties and port steelwork exposed to constant salt-laden air and splash.
Water & Effluent Infrastructure
Protective coat on ballast tanks, storage tanks, sluice gates and steel in waste-water and effluent treatment works.
Power, Chemical & Fertiliser Plants
Abrasion- and chemical-resistant topcoat for plant equipment and structural steel in aggressive industrial atmospheres.
Frequently asked questions
Is ShaliUrethane TC aromatic or aliphatic polyurethane?
What primer should be used under it?
What DFT and coverage should I plan for?
How long before I can overcoat or handle the work?
Can it be brush or roller applied, or is spray mandatory?
What pack size does it come in and how long does it store?
How we position STP ShaliUrethane TC
ShaliUrethane TC is the exposed finish layer of an STP protective system: pair it with ShaliPrime MIO PU as the specified primer, and in a full stack it follows a zinc-rich or epoxy primer with an MIO intermediate coat. Where a project needs an elastomeric PU waterproofing membrane rather than a rigid topcoat, look at STP’s ShaliUrethane BTD; for aggressive chemical immersion, STP’s epoxy protective coatings are the better call. Across our other brands, teams already standardised on Fosroc can achieve the same UV-stable finish with the Fosroc range, while high-chemical-resistance duties suit MC-Bauchemie or Sika protective coatings that we also supply.
Fosroc Nitocote PU Aliphatic — A specifier already standardised on Fosroc protective systems, or one needing Fosroc-approved documentation on the project, may prefer Nitocote PU Aliphatic — it is the closest like-for-like single-component aliphatic PU topcoat for steel and concrete.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.