High-Temperature Sealants

High-Temperature Sealants for Industrial Sealing & Jointing

Industrial high-temperature sealing involves more than choosing a product with a sufficiently high temperature rating. The sealant or compound must also suit the materials being joined, the amount of movement in the joint, the application method and the conditions encountered during operation.

The Vitcas range contains products for different functions, including sealing refractory and high-temperature substrates, filling joints and cracks, bonding insulation materials and creating fire-resistant seals. These products are not interchangeable, and the correct choice depends on how and where the material will be used.

High-Temperature Sealing Compounds for Thermal Equipment

High-temperature sealing compounds are intended for fixing, jointing and sealing materials exposed to substantial thermal loads. Depending on the individual product, compatible substrates can include ceramics, metals, glass and silica-based refractory materials.

These products are relevant to industrial furnaces, kilns, boilers, heat-treatment equipment and other thermal installations where conventional general-purpose sealants may not be suitable. The operating temperature and substrate should always be checked against the specification of the selected product.

Flexible High-Temperature Silicone for Moving Joints

Heat-resistant silicone performs a different function from refractory sealing compounds. Its flexibility makes it suitable for compatible joints where thermal movement or expansion and contraction need to be accommodated within the product's specified temperature range.

For industrial installations, this can include selected joints around flues, boilers, ovens, gaskets, metal components and other heated equipment. Flexible silicone should not be selected simply because a joint becomes hot; its maximum service temperature must remain suitable for the actual exposure.

Fire Cements & High-Temperature Jointing Compounds

Fire cements and flue cements provide rigid jointing and sealing solutions for specific high-temperature applications. Depending on the formulation, they can be used with refractory brickwork, clayware, flue components and other compatible mineral substrates.

These materials perform a different role from flexible silicone. Where movement needs to be accommodated, a suitable flexible product may be required; where a rigid high-temperature joint is appropriate, a cement or refractory sealing compound may be the better option. Always follow the intended use stated for the individual product.

Fillers for High-Temperature Boards & Joints

Heat-resistant fillers are intended for filling selected cracks, joints and surface imperfections rather than functioning as general-purpose joint sealants.

Within high-temperature construction and insulation systems, they can be used where compatible boards or similar materials need joints or small defects to be filled before the installation is completed. Product-specific temperature limits, substrates and application instructions should be checked before use.

Adhesives for Refractory & High-Temperature Insulation Systems

The category also includes specialist bonding compounds for installing materials used around industrial heat.

Heat-resistant board adhesives are used for jointing and fixing compatible high-temperature, insulation and construction boards to suitable substrates. Ceramic fibre adhesives are intended for bonding ceramic fibre products such as blankets, boards and modules to compatible refractory, brick or metal surfaces.

These products are particularly relevant to furnace, kiln and thermal insulation work where the material needs to be secured as part of a high-temperature lining or insulation system.

Fire-Rated & Intumescent Sealants

Fire-rated and intumescent sealants should be distinguished from products designed primarily for continuous high-temperature service. Their principal role is fire protection within specified joints or building elements rather than routine exposure to the operating temperature of a furnace or process installation.

An intumescent product reacts to fire conditions in a different way from a refractory sealing compound or heat-resistant silicone. Fire resistance, high-temperature resistance and flexibility are therefore separate properties and should not be treated as equivalent when selecting a sealant.

Industrial Applications for High-Temperature Sealants

High-temperature sealants and associated compounds can be used throughout industrial thermal installations for joining, sealing, bonding and maintenance tasks. Depending on the selected product, applications may include:

• industrial furnaces and kilns;
• boilers and high-temperature plant;
• heat-treatment equipment;
• refractory linings and brickwork;
• ceramic fibre and insulation systems;
• high-temperature boards and thermal enclosures;
• flues and exhaust-related components;
• metal, ceramic and glass components exposed to heat;
• industrial fire-protection joints where a suitable fire-rated product is specified.

The products required for these applications can differ substantially. A flexible joint, refractory joint, insulation bond and fire-rated penetration or construction joint should not automatically use the same sealing material.

Choosing the Right High-Temperature Sealant

For industrial applications, consider the complete service conditions before selecting a sealant or bonding compound.

• Maximum service temperature – check the rating of the individual product against the expected operating temperature.
• Joint movement – establish whether the finished joint needs to remain flexible or can be rigid.
• Substrate – identify whether the material will be applied to metal, ceramic, glass, refractory brick, board, ceramic fibre or another surface.
• Function – determine whether the product needs to seal, joint, fill, bond or provide a specified fire-protection function.
• Thermal exposure – consider continuous heat, intermittent heat and thermal cycling where relevant to the installation.
• Application location – establish whether the material will be used within thermal equipment, around a heated component or as part of a building fire-protection system.
• Preparation and curing – follow the surface preparation, curing and initial heating instructions given for the individual product.

A higher temperature rating does not automatically make one sealant more suitable than another. The correct product is the one whose temperature range, physical characteristics and intended application match the actual joint or installation.

Frequently Asked Questions

What are industrial high-temperature sealants used for?

Industrial high-temperature sealants are used for sealing, jointing, fixing or filling selected areas exposed to elevated temperatures. Applications can include furnaces, kilns, boilers, thermal processing equipment, refractory components and high-temperature insulation systems. The required material depends on the substrate, operating temperature, joint movement and whether the application requires sealing, bonding, filling or another specific function.

How do I choose between high-temperature silicone and a refractory sealant?

The main considerations are temperature exposure and joint movement. High-temperature silicone remains flexible and is suitable for compatible joints that need to accommodate movement within its specified temperature range. A refractory high-temperature sealing compound is intended for substantially hotter applications and compatible refractory, ceramic, metal, glass or silica-based materials. Check the individual temperature rating and intended use rather than treating the two products as interchangeable.

How do I choose between fire cement, high-temperature sealant and heat-resistant silicone?

Choose according to the type of joint and operating conditions. Fire cement is suited to selected rigid high-temperature joints and repairs, while a high-temperature refractory sealant is used for sealing and jointing compatible materials under greater thermal exposure. Heat-resistant silicone remains flexible and is more appropriate where compatible joints need to accommodate movement. Always check temperature and substrate compatibility before selection.

Are all high-temperature sealants flexible?

No. High-temperature sealing products can have very different physical characteristics. Silicone products are designed to retain flexibility, whereas cements, fillers and other refractory compounds can form comparatively rigid joints or repairs. Flexibility should therefore be treated as a specific product requirement rather than a general characteristic of all high-temperature sealants.

Can high-temperature sealants be used on metal, ceramic and glass?

Selected products can be used on metal, ceramic, glass and silica-based materials, but compatibility varies by formulation. The substrate should be identified before choosing the sealant, especially where different materials meet in the same joint. Check the product page or technical information to confirm that the selected compound is suitable for each surface involved.

Can high-temperature sealants be used in furnaces and kilns?

Yes, selected high-temperature sealing and bonding products are suitable for furnace, kiln and other industrial thermal applications. The appropriate product depends on where it will be installed and what it needs to do. A refractory joint, ceramic fibre bond, board joint and flexible connection may each require a different material, even within the same furnace or kiln installation.

Can high-temperature sealants be exposed to direct flames?

Direct flame resistance depends on the formulation and must not be assumed for every high-temperature sealant. Flue cement is intended for high-temperature flue jointing applications, while flexible heat-resistant silicone is designed for lower-temperature joints where movement may occur. For applications inside or close to a combustion area, use only a product specifically stated as suitable for direct flame exposure and check the individual product specification before installation.

What is the difference between a high-temperature sealant and a fire-rated sealant?

A high-temperature sealant is selected primarily for service in an environment exposed to elevated operating temperatures. A fire-rated or intumescent sealant is designed to provide a specified fire-protection function in appropriate building joints or penetrations. A product being fire resistant does not automatically mean it is suitable for continuous furnace temperatures, and high-temperature resistance does not automatically provide a particular fire rating.

Can ceramic fibre adhesive be used as a general-purpose high-temperature sealant?

It should be selected primarily for its intended bonding application. Ceramic fibre adhesive is designed to secure compatible ceramic fibre products, including blankets, boards and modules, to suitable surfaces such as refractory materials or metal. If the requirement is to seal a joint rather than bond insulation, a dedicated sealing compound may be more appropriate.

How should surfaces be prepared before applying a high-temperature sealant?

Surface preparation depends on the individual product, but the substrate generally needs to be suitable for bonding and prepared in accordance with the product instructions. Remove contamination or loose material where specified and observe any requirements concerning dryness, application thickness or tooling. Do not apply one preparation procedure to every sealant in the category because different formulations can have different requirements.

Do high-temperature sealants need to cure before the equipment is heated?

Curing and initial heating requirements vary between products. Some sealing compounds cure or set at room temperature and may require controlled heating afterwards, while silicones, cements, fillers and adhesives can have different procedures. Follow the instructions supplied with the individual product before exposing the completed joint or bond to its normal operating temperature.