STP ShaliPoxy CTE 103 I
Two-pack coal tar epoxy tested to IS 14948:2001 — a flexible, direct-to-metal barrier for buried pipelines, penstocks, sewage structures and marine splash zones that stay wet for decades.
What is it?
A black, two-component epoxy resin coating modified with coal tar, mixed 3:1 by volume and tested to IS 14948:2001. Supplied in 20 L packs by STP Limited.
Where is it used?
Buried and immersed steel or concrete — underground pipelines, penstocks, barrage gates, sewage treatment structures, crude-oil tank protection and dock splash zones. Not for potable water contact.
Why use it?
It goes direct to blast-cleaned metal without a primer, builds 108–145 microns DFT per coat, stays flexible under structural movement and works alongside cathodic protection.
How is it applied?
Brush, roller or airless spray in two or more coats on Sa 2½ blasted steel or 28-day-old concrete, with a 5–8 hour recoat interval at 30°C.
About STP ShaliPoxy CTE 103 I
ShaliPoxy CTE 103 I is the IS 14948:2001 grade in STP Limited’s coal tar epoxy range — a two-pack system in which epoxy resin is modified with coal tar to produce a tough, black protective film for steel and concrete that live underground or underwater. Mixed 3:1 by volume, the coating carries 73 ± 2% volume solids and lays down 108–145 microns of dry film per coat at a theoretical covering capacity of 5.0–6.50 m² per litre; applied wet-on-wet it can deliver 120–140 microns in a single pass. Because it bonds direct to metal, freshly blasted steel can be coated without a separate primer — a genuine time saver on pipeline yards and fabrication shops.
Space Arc Engineering supplies ShaliPoxy CTE 103 I as an authorised STP distributor and applicator, with stock movement across Delhi NCR and Pan-India project delivery. We back every supply with the current TDS and MSDS, help contractors reconcile theoretical coverage against site wastage, and can quote applied rates where blast-cleaning and coating are needed as a single package.
The technical insight
Coal tar epoxies work because the two ingredients cover each other’s weaknesses. The epoxy component cross-links into a hard matrix with strong adhesion — 6.25 mm mandrel flexibility and a 2 m impact pass in this grade show the film keeps that adhesion even when the substrate flexes. The coal tar fraction is intensely hydrophobic; dispersed through the cured matrix, it slashes water and vapour transmission, which is why the film survives permanent immersion where plain epoxies slowly saturate and blister. The same tar-rich film has high electrical resistance, so on cathodically protected pipelines it resists the alkaline conditions generated at coating defects — CTE 103 I passes the IS 14948 Annex G seawater-under-cathodic-protection test, making it a legitimate companion to impressed-current or sacrificial-anode systems.
Where it is used
- Underground and buried steel pipelines, including cathodically protected lines
- Penstocks, barrage gates and dam appurtenances in hydro and irrigation schemes
- Sewage treatment plant structures and effluent-handling concrete (non-potable service)
- External protection of crude-oil storage tanks and underground steel structures
- Foundation walls, basement retaining faces and sump pits in contact with ground water
- Splash zones on jetties, docks and harbour structures
- Mild steel and concrete elements under continuous immersion or permanently damp service
Key advantages
- Tested to IS 14948:2001 — drops straight into Indian government and PSU tender specifications
- Direct-to-metal application on Sa 2½ blasted steel; no primer required
- High 73 ± 2% volume solids builds 108–145 micron DFT per coat, reducing coat count
- Flexible cured film passes a 6.25 mm mandrel bend and 2 m impact test, tolerating substrate movement
- Long 8-hour pot life at 21°C gives crews a full shift from one mix
- Resists sea and salt water, crude oil, dilute acids, alkalis and abrasion in immersed service
- Compatible with cathodic protection — passes IS 14948 Annex G seawater/CP testing
- Low-viscosity formulation applies cleanly by brush, roller or airless spray
Limitations & considerations
- Not recommended for surfaces in contact with potable water or foodstuffs — specify a potable-grade epoxy lining for drinking-water assets
- Contains coal tar and is flammable: full PPE, forced ventilation in confined spaces and ignition control are mandatory
- Available in black only, and like all epoxies it chalks under prolonged sunlight — a cosmetic, not protective, loss
- Needs a 10–40°C application window with RH below 80% and substrate moisture under 5%; cold, damp or rain-threatened conditions stall the cure
- Recoat discipline matters: beyond 16 hours the previous coat must be solvent-wiped to regain intercoat adhesion
- Steel must be blast-cleaned to ISO Sa 2½ — budget for abrasive blasting, not just wire brushing
Selection & best practice
Blast steel to ISO Sa 2½ and coat immediately, before gingering sets in; on concrete, wait 28 days and blow surfaces clean with compressed air. Confirm the substrate is at least 3°C above dew point with ambient RH no higher than 80%. Stir each component separately, then combine A and B at 3:1 by volume and power-mix for 3–5 minutes with a slow-speed stirrer, paddle kept below the surface — never mix by hand. Apply the material as supplied; if flow demands it, thin only 1–5% with STP Thinner, accepting slightly lower film build. Lay the first coat at 150–200 microns WFT, recoat after 5–8 hours at 30°C, and solvent-wipe if the window stretches past 16 hours. For airless spray use a 70:1 pump, 0.88–0.98 mm tip at 250–280 kg/cm². Clean tools promptly with STP Thinner. Where a primer is preferred, ShaliPrime CT or ShaliPrime Zn Ph 60 are the recommended matches.
Specifications
| Form / colour / mixing ratio | Two-component coal tar epoxy, black; Comp A : Comp B = 3:1 (v/v) |
| Volume solids (IS 101-8-6) | 73 ± 2% |
| Film build per coat | WFT 150–200 µm; DFT 108–145 µm at 5.0–6.50 m²/L theoretical coverage |
| Drying time at 30°C, 55% RH (IS 101-3-1) | Surface dry 2–3 hours; hard dry 14–16 hours |
| Pot life (Annex E, IS 14948) | 8 hours at 21°C (100 g mix) |
| Density of mix (ASTM D 1475) | 1.40 ± 0.03 g/cc |
| Flexibility and adhesion (IS 101-5-2) | Passes on 6.25 mm diameter mandrel after 7 days curing |
| Standard compliance | IS 14948:2001; sea water resistance under cathodic protection passes Annex G |
| Packaging / shelf life | 20 L unit (15 L Comp A + 5 L Comp B); 12 months sealed at 5–38°C |
Industry use cases
Water & Wastewater Infrastructure
Protects STP clarifiers, effluent channels and sump structures where concrete faces continuous sewage and dilute chemical attack — strictly non-potable service.
Hydropower & Irrigation
The specified duty for penstocks, barrage gates and dam steelwork under Indian irrigation department tenders that call up IS 14948 coal tar epoxy paint.
Oil & Gas / Tank Farms
Shields crude-oil storage tank exteriors and buried plant steel against soil-side corrosion, with resistance to crude, oils and salt-laden ground water.
Buried Pipelines & Utilities
Direct-to-metal coating for underground pipelines, proven compatible with cathodic protection systems on cross-country and in-plant lines.
Marine & Ports
Handles the splash-zone cycle of wetting, drying, abrasion and salt at jetties, docks and harbour structures where coating access is rare.
Frequently asked questions
Can I use ShaliPoxy CTE 103 I inside a drinking-water tank?
What coverage should I budget per coat?
What is the difference between ShaliPoxy CTE 103 and CTE 103 I?
Do I need a primer before applying it on steel?
How many coats are needed and what is the recoat window?
Is it compatible with cathodic protection on pipelines?
How we position STP ShaliPoxy CTE 103 I
Within the STP family, keep the grades straight: specify ShaliPoxy CTE 103 where tenders cite AWWA C-210 or SSPC Paint 16, and CTE 103 I where IS 14948:2001 is the governing standard; pair either with ShaliPrime CT or ShaliPrime Zn Ph 60 when a primed system is required. Where the specification demands a solvent-free, 100%-solids epoxy-tar film for permanently immersed sewage or seawater structures, Fosroc Nitocote ET402 from our range is the natural step up. And if the asset holds drinking water, move away from coal tar chemistry altogether — talk to us about potable-grade epoxy linings before you specify.
Fosroc Nitocote ET402 — Specifiers choose Nitocote ET402 when the job calls for a solvent-free, 100%-solids coal-tar-extended epoxy for permanently immersed sewage, effluent or seawater structures rather than a solvented coal tar epoxy.
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