STP ShaliModulate LS
Hot-pour, low-smell coal tar modulate from STP Limited for long-life corrosion protection of buried pipelines, structural steel and concrete — supplied and applied by Space Arc Engineering across Delhi NCR and Pan-India.
What is it?
A single-component, hot-applied coal tar modulate made by digesting bituminous coal in a solution of pitch and high-boiling coal tar distillate. The LS grade is formulated for markedly lower odour than conventional coal tar enamels.
Where is it used?
External corrosion coating on buried steel pipelines carrying crude, product liquids or gas, and protective duty on structural steel and concrete exposed to aggressive soil, water or petroleum contact.
Why use it?
It bonds strongly to both steel and concrete, carries high electrical resistivity valued on cathodically protected lines, and resists water, petroleum products, bacteria, marine organisms, root growth and backfill damage.
How is it applied?
Cut into 1–5 kg pieces, melted in a kettle to application temperature — never beyond 260°C — and poured or brush-applied over a cleaned, primed, completely dry surface. Heated material must be consumed within 3 hours.
About STP ShaliModulate LS
ShaliModulate LS is a hot-pour coal tar modulate manufactured by STP Limited, formerly Shalimar Tar Products and one of India’s longest-running coal tar and bitumen processors. It is produced by digesting bituminous coal in a solution of pitch and high-boiling coal tar distillate, giving a dense protective compound — 1.30 to 1.40 g/cm³ at 25°C — with a Ring & Ball softening point of 95 to 110°C. Delivered as solid material in 250 kg drums, it is melted on site and applied hot to steel and concrete.
The LS suffix stands for Low Smell. Standard hot coal tar work generates fumes strong enough to trigger complaints in occupied plants and built-up corridors; this grade cuts that odour substantially while keeping the water-tightness, dielectric strength and biological resistance that have kept coal tar systems on buried pipelines for decades. For pipeline contractors, refinery maintenance teams and consultants specifying soil-side protection, it remains one of the most economical long-service coatings available, and Space Arc Engineering supports it with genuine STP supply and trained hot-application crews.
The technical insight
The chemistry does two jobs at once. Digesting bituminous coal into pitch and high-boiling distillate produces a modulate whose softening point of 95–110°C sits far above any buried-service temperature — so the film stays firm under soil load — yet melts to a pourable fluid in an ordinary site kettle. The two penetration values tell the flexibility story: 8–18 (0.1 mm) at 25°C under 100 g, opening to 15–40 at 45°C under 50 g, meaning the coating is hard enough to shrug off backfill pressure but retains enough give to follow pipe movement without cracking. The aromatic coal tar structure itself is what buyers are really paying for: it is intrinsically hostile to bacteria, marine organisms and roots, barely absorbs water or petroleum products, and exhibits high electrical resistivity — so on a cathodically protected line the coating leaks very little current and CP demand stays low for years.
Where it is used
- External anti-corrosion coating of buried steel pipelines carrying crude oil, refined products, other liquids or gas
- Protective coating of structural steel in contact with soil, groundwater or aggressive industrial exposure
- Protection of concrete substructures — foundations, pedestals, plinths and pile caps in aggressive soils
- Yard coating and recoating of pipe sections, bends and specials before lowering and burial
- Buried services threatened by root growth, backfill abrasion and soil bacteria
- Steel and concrete in marine-influenced ground where organism attack degrades ordinary coatings
- Plants and ventilation-restricted work fronts where the odour of conventional hot coal tar is unacceptable
Key advantages
- Excellent adhesion to both metal and concrete from a single product
- High electrical resistivity — the property specifiers look for on cathodically protected pipelines
- Good flexibility with controlled temperature susceptibility across Indian service conditions
- Resistant to continuous contact with water and petroleum products
- Withstands bacteria, marine organisms, root growth and backfill damage
- Noticeably lower fume odour than standard hot-applied coal tar
- Single-component hot melt — no mixing ratios and no chemical pot life to misjudge
- Chemically stable film built for long buried-service life
Limitations & considerations
- Hot-applied only — needs a melting kettle, fuel, trained applicators and hot-work clearance; there is no cold-applied version of this grade
- Strict kettle discipline applies: material held at application temperature beyond 3 hours, or heated past 260°C, must be rejected — batch sizes must match the day’s output
- Low smell is not no smell — goggles, mask, nose cover and gloves are mandatory, and confined areas still need ventilation
- Demands a clean, primed, completely dry substrate; it will not tolerate damp, oily or dusty surfaces
- A black protective finish for buried or covered service — not a decorative or trafficable coating
- No published coverage figure — consumption must be established from specified thickness and a site trial
Selection & best practice
Cut the drum contents into pieces of roughly 1–5 kg to suit the kettle. Charge the kettle to about 40% of capacity, begin heating, and feed in the balance gradually as the melt turns fluid. Stir occasionally so material does not carbonise and coke at the kettle bottom — this also saves meaningful fuel. Hold the kettle below 260°C at all times and reject any batch that crosses it. Once application temperature is reached, consume the melt within 3 hours; if a plant breakdown interrupts work, shut the burner and hold the material at 180°C or lower with the agitator running, for no more than 8 hours. On reheating, old material left in the kettle should not exceed 10% of the fresh charge. Apply only onto external pipe, steel or concrete that has been cleaned, primed and verified free of dust, dirt, oil and moisture. Work in full PPE and wash up with warm soapy water afterwards.
Specifications
| Form | Hot-pour, low-smell coal tar modulate (solid, kettle-melted) |
| Density at 25°C | 1.30 – 1.40 g/cm³ |
| Softening point (Ring & Ball) | 95 – 110°C |
| Penetration at 25°C, 100 g | 8 – 18 (10⁻¹ mm) |
| Penetration at 45°C, 50 g | 15 – 40 (10⁻¹ mm) |
| Ash content by ignition | 5 – 10% by mass |
| Maximum kettle temperature | 260°C — reject material heated beyond this |
| Working time at application temperature | Within 3 hours |
| Packing | 250 kg drum |
Industry use cases
Oil & Gas Pipelines
External coating of buried cross-country and in-plant lines carrying crude, products or gas, where high dielectric resistance keeps cathodic protection current demand low over the asset’s life.
Refineries & Petrochemicals
Tank-farm interconnecting piping, buried utility lines and structural steel bases exposed to petroleum spillage and contaminated soils — service the coating is inherently resistant to.
Water & Utility Infrastructure
Soil-side protection of buried steel mains, casing pipes and utility crossings where backfill abrasion and root ingress destroy lighter coatings.
Ports & Marine Facilities
Steel and concrete in saline ground and marine-influenced zones, using coal tar’s natural resistance to marine organisms and bacteria.
Industrial Plants
Concrete foundations, pedestals and embedded steel in aggressive plant soils — with the low-smell grade easing application inside operating facilities.
Frequently asked questions
What does the LS in ShaliModulate LS actually mean — is it odour-free?
Do I need a primer before applying it?
How long can the melted material sit in the kettle?
How do I estimate the quantity needed for my pipeline job?
Can it be applied during the monsoon?
Is there a cold-applied alternative if hot work is not permitted on site?
How we position STP ShaliModulate LS
ShaliModulate LS anchors the hot-applied end of STP’s coal tar protection family. For cold-applied, solvent-free anti-corrosive duty on steel and concrete, the ShaliDCT 101–104 processed dehydrated coal tars cover most maintenance work, while ShaliDCT 105 adds polyurethane compatibility where a PU topcoat or membrane follows. ShaliPitch serves specialised industrial pitch requirements. Outside the STP range, specifiers who cannot get hot-work clearance often move to Fosroc Nitocote ET550, a two-pack coal tar epoxy we also stock. Space Arc Engineering supplies all of these ex-stock with TDS support and applicator crews across Delhi NCR and Pan-India.
Fosroc Nitocote ET550 — Specifiers choose this cold-applied, two-component coal tar epoxy when hot-work permits or kettle logistics rule out hot-pour application on live plant sites.
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