About STP ShaliProtek HR BT 300

ShaliProtek HR BT 300, formerly catalogued by STP as HR BT 260, is a specialist heat-resistant coating built for one of the harder corners of industrial asset protection: the hidden steel that sits behind insulation and inside hot equipment. It is an asphalt-based emulsion that goes on cold, without solvents, and cures into a thick, matt, rubber-like film. Because it is water-carried rather than solvent-borne, it is non-toxic and low-odour on site, which matters when crews are working inside furnace casings or in the tight annular space around insulated pipework. Applied correctly, it builds a coating up to 6 mm thick in just two coats without slumping off vertical steel.

What sets this product apart from an ordinary bituminous paint is its combination of heat tolerance and permanent flexibility. It is rated for service up to 300C, so it holds up on furnace and boiler casings and on chimney interiors where an unmodified bitumen would soften and run. At the same time it never fully hardens into a brittle shell; it stays plastic so it can stretch and relax as the underlying pipe or vessel expands on heat-up and contracts on cool-down. That single property is what makes it a genuine under-insulation-corrosion (UIC) solution rather than just a coating that happens to survive some heat.

The technical insight

Under-insulation corrosion is driven by a simple, destructive cycle: moisture works its way through cladding and lodges in the insulation against warm steel, and the wetting-drying-heating pattern rusts the pipe out of sight until a leak reveals it. ShaliProtek HR BT 300 breaks that cycle by acting as a continuous vapour barrier laid directly on the steel, under the rock wool. Its high asphalt solids content (volume solids above 50 percent) means each pass leaves a substantial, low-permeability film rather than a thin skin, so liquid water and water vapour simply cannot reach the metal. The plasticity is equally deliberate. On a hot pipe the differential movement between steel and coating would crack a rigid film and open a corrosion path; keeping the bitumen permanently soft lets the film track that movement and self-seal minor disturbances. The two-coat, brown-to-black cure sequence is a built-in verification tool – the colour change tells the applicator the first coat has properly broken and coalesced before the second goes on – and the sand broadcast at 200 g/m2 keys the surface so overlying insulation or a topcoat grips instead of slipping.

Where it is used

• Internal casing surfaces of industrial furnaces and boilers
• Firebrick and refractory lining backing surfaces
• Interior surfaces of chimneys and flue casings
• External face of MS pipes over rock-wool insulation, before aluminium cladding, for under-insulation corrosion protection
• Vapour-barrier layer on insulated hot and chilled pipework
• Protection of vessel and duct casings exposed to corrosive process chemicals
• Corrosion protection of steel substrates subject to thermal cycling up to 300C

Key advantages

• Rated for continuous service up to 300C, well beyond ordinary bituminous paints
• Stays permanently plastic, accommodating thermal expansion and contraction without cracking
• Excellent moisture and vapour-barrier performance that arrests under-insulation corrosion
• Builds up to 6 mm in two coats without sagging on vertical steel
• Solvent-free, water-based formulation – non-toxic, low-odour and safer inside confined casings
• Cold-applied by brush or trowel, needing no hot works or specialist plant
• Helps retain the thermal efficiency of the insulation system it protects
• Supplied ready-to-use in 20 kg containers, simple to thin and mix on site

Limitations & considerations

• Water-based cure means it needs an ambient application temperature of 4C to 48C and adequate ventilation to dry properly
• Hard-dry takes around 48 hours, and 24 hours is required between the two coats – it is not a fast-turnaround system
• The 300C ceiling is a service limit; it is not a fire-rated or intumescent product for direct-flame exposure
• Coverage of about 2.6 kg/m2 per 1 mm DFT makes a full 6 mm build a material-heavy application to budget for
• Shelf life is only 6 months in sealed containers, so stock should be rotated and not over-ordered
• Performance depends on thorough surface preparation – loose scale, oil or grease under the film will undermine adhesion

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliProtek HR BT 300

ShaliProtek HR BT 300 sits at the specialist, high-temperature end of STP’s protective-coatings range and rarely competes head-to-head with general waterproofing bitumens – it is chosen specifically for furnace casings and under-insulation corrosion duty. Within the STP family it complements the lower-temperature ShaliProtek HR BT 100, which suits similar UIC work where the 300C ceiling is not required, and pairs naturally with STP’s aluminium/heat-reflective finishes over insulated lines. For ambient below-ground or tanking waterproofing on steel and concrete, a conventional cold-applied bitumen such as those in the Fosroc Nitoproof line or Dr. Fixit’s bituminous coatings is the correct, more economical choice – but neither is a substitute here, since they are not formulated for sustained heat or the permanent plasticity that UIC on hot pipework demands. If you are unsure whether your line temperature and insulation build call for HR BT 300 or a standard bituminous coating, our team can specify the right product for the operating conditions.

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