Insulation Jackets & Flue Wraps

Selecting Insulation Jackets, Flue Wraps & Flexible Thermal Insulation

Flexible insulation jackets, flue wraps and high-temperature blankets are used where rigid insulation is difficult to install or where the material must conform to cylindrical, curved or irregular surfaces. VITCAS solutions cover applications ranging from stove flues and chimney liners to pipework, ducts, furnaces, kilns, turbines and other thermal-processing equipment.

The products use different fibre and facing constructions, so they should not be selected by headline temperature alone. Glass fibre flue insulation provides practical thermal protection up to 550°C, while bio-soluble fibre blanket extends the available insulation duty up to 1200°C. Where aluminium foil is used as a facing, its temperature capability must be considered separately from that of the underlying insulation.

Key Technical Characteristics of Flexible Thermal Insulation

• High-temperature insulation: E-glass flue wraps provide thermal insulation up to 550°C, while bio-soluble fibre blanket is available for more severe thermal duties up to 1200°C.
• Reduced heat transfer: low-conductivity fibrous insulation helps limit unwanted heat loss through flues, pipework, ducts and equipment casings when the correct material and thickness are used.
• Flexible construction: blankets and wraps can conform to round, curved and irregular geometries that would be more difficult to insulate with rigid boards.
• Low thermal mass: lightweight fibre insulation stores relatively little heat, making it suitable for equipment where reduced heat storage and responsive heating or cooling are desirable.
• Reflective facing: aluminium-faced products provide a reflective outer surface and can also act as a vapour-resistant facing, but the aluminium layer may have a lower temperature limit than the insulation beneath it.
• Practical fabrication: flexible products can be cut, wrapped and fitted around compatible equipment. Abrasion resistance, moisture resistance, removability and long-term durability depend on the complete fibre, facing, fixing and protective construction.

Glass Fibre Flue Wrap vs Bio-Soluble Insulation Blanket

Insulation Type	Published Temperature Capability	Typical Function	Important Selection Point
Aluminium-Coated Glass Fibre Flue Wrap	Glass fibre: up to 550°C Aluminium facing: best suited up to approximately 300°C	Flues, chimney liners, pipes, ducts and reflective thermal insulation	Above the facing limit, position the glass fibre towards the hotter surface and the aluminium face away from the heat source
E-Glass Flue Insulation Wrap	Up to 550°C	Flexible insulation around compatible flues and chimney liners	Confirm flue diameter, installation geometry and compatibility with the chimney system
Bio-Soluble Insulation Blanket with Aluminium Foil	Blanket rated up to 1200°C	Higher-temperature insulation for furnaces, kilns, turbines, pipework, exhausts and thermal-processing equipment	Consider the blanket and its facing as separate layers when assessing temperature exposure

Flue & Chimney Insulation

Flue insulation is one of the principal applications for flexible glass fibre wraps. Insulating a compatible flue or chimney liner helps reduce heat loss from the flue gases as they travel through the chimney.

Keeping the liner warmer can reduce the conditions that encourage condensation and tar formation and can support more stable chimney draught. This is particularly relevant where flue gases would otherwise cool rapidly as they pass through colder chimney spaces.

Flue wrap should not be used to compensate for an unsuitable chimney design, defective liner or inadequate clearance from combustible materials. The insulation must be compatible with the flue system, and required access for inspection, cleaning and maintenance should be maintained.

Glass Fibre and Aluminium Facing Have Different Temperature Limits

With VITCAS Aluminium-Coated Insulation Flue Wrap, the glass fibre layer is suitable for continuous temperatures up to 550°C, while the aluminium foil facing is best suited to temperatures up to approximately 300°C.

These values apply to different parts of the same product. The 550°C rating of the glass fibre should therefore not be interpreted as a 550°C direct-exposure rating for the aluminium surface. Where temperatures exceed the facing limit, the glass fibre side should face the hotter surface and the aluminium side should be orientated away from the direct heat source.

Pipework, Ducts & Thermal Equipment

Flexible insulation can be wrapped around compatible hot pipes, steam lines, ducts and other thermal equipment where reducing heat transfer is required. The ability of fibre insulation to conform to curved surfaces helps reduce the number of joints that may be required with rigid insulation products.

The correct thickness depends on operating temperature, pipe or duct diameter, ambient conditions and the required thermal result. Where accessible surface temperature is important, it should be assessed from the complete insulation construction rather than assumed from the blanket temperature rating.

Furnaces, Kilns & High-Temperature Process Equipment

VITCAS Bio-Soluble Insulation Blanket with Aluminium Foil provides higher-temperature flexible insulation for applications up to 1200°C. Typical uses include furnaces, kilns and other thermal-processing equipment where low thermal conductivity, low heat storage and flexibility are required.

Flexible fibre blanket may be used as primary insulation in suitable protected positions or as a backup layer within a multi-material refractory system. It should not automatically be treated as a mechanically durable hot face where abrasion, impact, high gas velocity or direct process contact is severe.

Boilers, Steam Systems & Power Generation

Bio-soluble fibre blanket can be used for compatible boiler, steam-system and turbine insulation where the operating temperature is within the material's published capability. Flexible insulation is useful around equipment with curved or complex geometries and can help reduce unwanted thermal losses from hot surfaces.

For industrial insulation systems, temperature is only one design variable. Mechanical retention, vibration, access requirements, weather exposure and the design of the outer protective layer can all affect long-term performance.

Petrochemical & Process Industry Insulation

High-temperature fibre blankets are also used around suitable reactors, pipework and process equipment in petrochemical and other thermal-processing environments.

Process compatibility must be considered separately from temperature capability. Oils, chemicals, vapours, pressure conditions and contamination can affect facings, adhesives, fixings and other components even where the fibre insulation itself remains within its thermal limit.

Automotive, Marine & Exhaust Applications

Flexible high-temperature fibre insulation can be used in compatible exhaust systems, heat shields and engine-related thermal barriers in automotive, aerospace, industrial and marine applications.

These applications may combine high temperature with vibration, restricted installation space, air movement, oil contamination and repeated thermal cycling. The insulation therefore needs suitable containment or facing where exposed to demanding mechanical conditions.

Use in Low-Temperature & Cryogenic Insulation

Fibrous insulation materials can also be used in selected low-temperature and cryogenic systems where limiting heat ingress is required. Suitability depends on the specific insulation material, moisture and vapour control, facing construction, operating temperature and the design of the complete system. Products in this category should therefore only be specified for cryogenic duty where their individual properties and installation requirements are compatible with the application.

Temperature Rating Does Not Define the Complete Insulation System

The published temperature of an insulation fibre describes the thermal capability of that material under its stated conditions. It does not automatically apply to every facing, tape, adhesive, fixing or adjacent component used in the installation.

When specifying flexible high-temperature insulation, consider:

• normal operating temperature at the insulation position;
• short-duration temperature peaks and thermal cycling;
• temperature capability of the fibre and facing separately;
• required insulation thickness;
• thermal conductivity at the relevant mean temperature;
• flue, pipe or equipment diameter and geometry;
• moisture, weather and chemical exposure;
• abrasion, vibration and mechanical damage;
• fixing, wrapping or containment method;
• access required for inspection and maintenance.

A blanket rated to 1200°C does not mean that the external face of an insulated component will remain at a particular safe temperature. Cold-face temperature depends on insulation thickness, thermal conductivity, hot-face temperature, ambient conditions, thermal bridges and the complete construction.

Reducing Heat Loss with Flexible Insulation

Correctly specified insulation reduces heat transfer between hot equipment and its surroundings. This can reduce unnecessary energy loss and support more efficient operation, particularly on systems that remain hot for long periods.

The actual energy saving cannot be determined from temperature rating alone. Surface area, operating temperature, insulation thickness, thermal conductivity, operating hours and ambient conditions all influence the thermal and economic result.

Flexible Insulation vs Removable Insulation Jackets

A flexible insulation blanket or flue wrap is not automatically a finished removable insulation jacket. Removable jackets for valves, flanges, turbines and process equipment are fabricated systems that may combine an internal insulation layer with an outer technical fabric, stitching, closures and mechanical fixings.

Where a removable cover is required, every part of the assembly should be suitable for the temperature, mechanical load and environmental exposure. The outer fabric, sewing thread, fasteners and closures can have different limits from the insulation enclosed within the jacket.

Frequently Asked Questions

What temperature can VITCAS flue wrap withstand?

The glass fibre insulation in the aluminium-coated flue wrap is rated up to 550°C. The aluminium facing has a separate lower limit and is best suited to temperatures up to approximately 300°C.

Which side of aluminium flue wrap should face the heat?

Where temperatures exceed approximately 300°C, the glass fibre side should be positioned towards the hotter surface and the aluminium-facing side away from direct high-temperature exposure.

Why insulate a chimney flue or liner?

Flue insulation reduces heat loss from the flue gases and helps the liner remain warmer. This can reduce conditions that contribute to condensation and tar formation and can support more stable chimney draught.

Can flue wrap reduce the required clearance to combustible materials?

Not automatically. An insulation wrap should not be used to justify a reduction in the clearance specified for the appliance or chimney system unless the complete installation has been designed and approved for that arrangement.

What is the highest-temperature flexible insulation in this group?

VITCAS bio-soluble fibre blanket provides insulation for compatible applications up to 1200°C. It is suited to higher-temperature thermal-processing equipment where standard E-glass insulation would exceed its temperature capability.

Can insulation jackets prevent burns from hot equipment?

Insulation can reduce heat transfer and may reduce accessible surface temperatures when correctly designed, but the external temperature depends on the complete insulation system. A material temperature rating by itself does not establish a safe-touch temperature.

Can these materials be used around pipes and ducts?

Yes, selected flexible fibre insulation products can be used around compatible hot pipework, ducts and thermal equipment. Select the material according to temperature, diameter, insulation thickness, environmental exposure and fixing method.

Are flexible insulation blankets reusable?

Some fabricated insulation covers are designed to be removable and reusable, but a blanket or flue wrap should not automatically be treated as a reusable jacket. Reusability depends on the complete construction, fixing system, condition of the fibre and facing, and the maintenance procedure.

Is a 1200°C blanket suitable for every furnace or kiln?

No. Temperature capability is only one selection criterion. Mechanical exposure, gas velocity, abrasion, lining position, thickness, containment and process atmosphere must also be considered before specifying fibre insulation.