Marine Refractory & Insulation

Marine Thermal Protection Is an Installed System

A marine installation must control heat without obstructing inspection, ventilation, drainage, emergency access or movement of the supporting structure. The hot component, insulation, outer covering, fixings, joints and adjacent materials must be considered together. A product suitable for a small heating appliance may be unsuitable on a propulsion-engine exhaust, inside a refractory-lined auxiliary boiler or within a regulated structural fire division.

Establish the vessel type, service and operating area first. A recreational craft, inland vessel, fishing vessel, workboat, commercial ship, ferry and passenger vessel can be subject to different construction, survey and approval routes. Retain the appliance, engine, boiler, incinerator, exhaust and vessel manufacturer's installation details. Consult the surveyor, certifying authority, classification society or flag Administration wherever statutory or class approval is required; SOLAS requirements do not automatically apply to every marine vessel.

Functions Within a Marine Thermal System

Material function	Typical marine use	Selection priorities
Dense refractory	Hot-face lining and local repair in compatible boilers, incinerators and combustion equipment	Temperature, flame pattern, fuel ash, erosion, anchors, vibration, curing and dry-out
Fibre or board insulation	Heat-flow control around suitable appliances, ducts, casings and protected machinery zones	Thermal conductivity, thickness, shrinkage, surface temperature, moisture and fixing method
Rope or rigid sealant	Specified stove-door, glass, flue and refractory joints	Joint movement, section, compression, substrate, temperature and gas tightness
Wrap or coated fabric	Selected dry exhausts, flues, ducts, removable insulation jackets and heat shields	Component temperature, coating limit, oil contamination, fastening, abrasion and inspection
Pipe thread compound	Approved threaded joints carrying a listed medium within defined pressure and temperature limits	Fluid, pipe material, thread form, pressure, temperature and system approval
Structural fire protection	Tested bulkheads, decks, linings, doors and penetrations	Complete assembly, FTP test, type approval, fire class, orientation, joints and approved fixings

Marine Heating Appliances and Flues

Product	Published limit	Potential use
Vermiculite Fire Board	1100°C	Workable insulation board around compatible covered heating installations where the complete clearance detail is verified
HT High Temperature Fireboard	650°C; A1 reaction to fire	Non-gypsum board for suitable heat-exposed linings and finishes outside an unverified marine fire division
White Stove Rope and Adhesive Kit	550°C	Replacement glass-fibre gasket for compatible stove doors, glass and defined flue joints
Black Stove Rope and Adhesive Kit	550°C	Black replacement gasket for compatible solid-fuel stove doors and other specified grooves
Aluminium-Coated Flue Wrap per Metre	Glass fibre 550°C; foil best suited up to 300°C	Cut-length insulation around suitable flues or liners where the flue design permits wrapping
Aluminium-Coated Flue Wrap Roll	Glass fibre 550°C; foil best suited up to 300°C	Longer-length version for an approved flue-insulation detail
Heat Resistant Silicone	315°C	Flexible sealing at compatible lower-temperature joints and external interfaces
BFC Black Fire Cement	1250°C	Rigid fine joints and minor repairs in compatible stove, fire-brick and internal flue assemblies
HRS Heat Resistant Sealant	1300°C	Rigid high-temperature joints on compatible refractory, metal, silica or glass substrates

Install a solid-fuel appliance and chimney to the manufacturer's marine instructions and the standard, code or examination scheme applicable to the vessel. Secure the appliance and hearth to the structure, maintain the prescribed clearances from combustible linings and furnishings, support the chimney independently and provide the required combustion air and accommodation ventilation. An insulation wrap must not be used to convert an unsuitable single-wall flue into an approved twin-wall or insulated chimney.

Choose rope by the original gasket section and groove, not by door size alone. An undersized rope can leak; excessive section or compression can prevent the latch from closing correctly. Black Fire Cement and HRS cure as rigid materials and should not replace a flexible gasket or bridge a joint designed to move. Heat Resistant Silicone remains flexible but is limited to 315°C and belongs only where the measured or calculated joint temperature stays within that limit.

Marine Boilers, Incinerators and Refractory Repairs

Product	Published temperature	Potential use
Refractory Castable Grade 1600	1600°C	Dense monolithic hot-face sections, burner areas and local repairs in compatible combustion equipment
Vitset 45 Refractory Mortar	1700°C	Air-setting mortar for jointing compatible dense or insulating refractory bricks
VITPLAST 45AB Plastic Mouldable	1600°C	Ram-installed local repair of compatible brick and monolithic industrial linings
Zircon Refractory Coating	1750°C	Thin coating over an approved refractory substrate where the process chemistry supports its use

Survey the original lining, anchors, expansion allowances, burner geometry and adjacent metalwork before demolition. Movement and vibration can expose weak interfaces that remain hidden in a stationary installation. Do not cover corroded boiler pressure parts, damaged burner components or failed anchors with refractory repair material.

Dense castable is not thermal insulation merely because it withstands high temperature. The hot face and backup insulation have different density, strength and heat-flow functions. Measure installation water accurately, cure the material and apply a controlled dry-out schedule before returning the equipment to full firing. A surface that appears dry can still contain enough moisture to create internal steam pressure and spalling.

Blankets for Thermal Insulation

Product	Published temperature	Potential use
Biosoluble Fibre Blanket	1200°C	Full-roll flexible insulation for protected equipment and lining zones
Biosoluble Insulation Blanket per Metre	1200°C	Cut-length flexible insulation for small areas and maintenance quantities
Biosoluble Blanket with Aluminium Foil	Blanket 1200°C; foil limit not stated	Faced blanket for suitable protected insulation and removable-jacket constructions after verifying the foil exposure
Ceramic Fibre Blanket 1260	1260°C	Full-roll flexible insulation for suitably contained and protected high-temperature zones
Ceramic Fibre Blanket 1260 per Metre	1260°C	Cut-length version for smaller maintenance and insulation projects

Calculate insulation thickness from the required external surface temperature, hot-side temperature, thermal conductivity at the relevant mean temperature, ambient conditions and every layer in the construction. Maximum material temperature does not predict the temperature of the casing, outer foil or nearby timber and composite linings.

In machinery spaces, insulation should be enclosed or faced where necessary to resist oil mist, fuel contamination, moisture and mechanical damage. Wet or contaminated insulation can lose performance and create an additional hazard. Arrange cladding, seams and drainage so that inspection for leakage and corrosion remains possible. Do not assume that an aluminium-facing temperature equals the higher rating of the fibre beneath it.

Dry Exhausts, Heat Shields and Technical Fabrics

Product	Published limit	Potential use
Titanium Basalt Fibre Tape	700°C	Wrap for compatible dry exhaust or high-temperature pipework where the equipment manufacturer permits insulation
Acrylic Double-Sided Glass Fibre Cloth	550°C stated for the cloth	Weather-resistant outer fabric for compatible removable jackets, covers and expansion details
PU-Coated Glass Fibre Cloth	550°C continuous; 600°C short term	Low-permeability outer cloth for engineered fire, smoke or removable-insulation constructions
Aluminium-Foil E-Glass Cloth	550°C stated for the composite cloth	Low-emissivity facing and outer layer for compatible insulation jackets and heat shields

First identify whether an exhaust is dry, water-injected or otherwise cooled. Do not wrap a wet exhaust hose or unapproved component with a material intended for a dry metallic exhaust. Adding insulation changes metal temperature, thermal expansion and the visibility of cracks or leakage; obtain permission from the engine or exhaust manufacturer and retain access to joints, sensors, bellows and supports.

Secure fabrics and tapes against vibration, chafe and exhaust gas velocity. Locate seams away from likely leakage paths and inspect fasteners after initial heat cycles. The temperature resistance of a base fabric does not necessarily apply to its acrylic, polyurethane, adhesive or aluminium-facing layer. Use the lowest applicable continuous limit in the complete construction.

Threaded Pipe Joints

Pipe Jointing Compound is described for threaded hot- and cold-water, natural-gas, LPG and low-pressure steam services up to 7 bar and 200°C. Confirm that the exact fluid, thread standard, pipe material, pressure and temperature fall within its certified scope and the vessel's approved piping specification. Do not infer suitability for diesel, petrol, hydraulic oil, potable water or a safety-critical marine fuel system from the words general purpose or non-toxic.

Structural Fire Protection and Marine Approval

Reaction to fire describes how an individual product contributes to ignition and fire growth. Fire resistance describes how a complete bulkhead, deck, door or penetration maintains integrity and insulation for a defined time. HT Fireboard's European A1 reaction-to-fire classification does not by itself create a marine A-class or B-class division. Likewise, the EN 45545-2 railway classification stated for HRS is not an IMO FTP Code approval.

Where SOLAS or national merchant-shipping rules apply, fire-safety products and assemblies may require testing under the IMO Fire Test Procedures Code and type approval by the flag Administration or an authorised body. Confirm the approval certificate, exact product identity, thickness, density, substrate, orientation, joint arrangement, fixings and permitted penetrations. Substitution or site-built combinations outside the certificate may invalidate the claimed class.

No material in this category should be described as marine approved, SOLAS approved, MED approved, an A-60 system or an approved penetration seal unless current documentation expressly covers that product and the installed assembly.

Moisture, Salt, Vibration and Corrosion

• Exclude water: protect absorbent boards and blankets from bilge water, spray, condensation and rain during storage and installation.
• Control contamination: replace insulation soaked with fuel, oil or chemicals in accordance with the vessel's maintenance procedure.
• Allow movement: accommodate vibration, hull flexing, thermal expansion and movement at equipment mounts without forcing rigid sealants into flexible joints.
• Prevent chafe: use compatible mesh, cladding, edge protection and fasteners where machinery vibration can abrade textiles.
• Inspect beneath insulation: provide removable sections or planned access for corrosion and leakage checks.
• Verify materials: select fixings and outer coverings that remain compatible with the substrate and marine atmosphere at temperature.

Installation and Maintenance Checks

Record the original clearances, material build-up, fasteners, penetrations and service temperatures before removing insulation. Isolate and cool the appliance, boiler, engine or exhaust and secure all relevant fuel, electrical, pressure and mechanical energy. Remove salt, oil, soot, corrosion and loose material using controls appropriate to the hazard.

After installation, commission the equipment under the manufacturer's procedure and inspect for smoke or gas leakage, abnormal casing temperature, odour, loose fixings and movement. Recheck after the first operating cycles because gaskets settle and wraps can relax. Keep repairs visible in the vessel maintenance record, including material batch, location, thickness, curing and any surveyor acceptance.

Inspect stove door rope, flue connections, chimney support, roof penetration, hearth, heat shields and nearby combustible surfaces regularly. In machinery spaces, examine exhaust joints, lagging, cladding, support brackets and signs of oil or water ingress. A new hot spot, soot mark, burnt edge, frayed fabric or hard and flattened gasket warrants investigation rather than another layer of insulation.

Frequently Asked Questions

Which materials may be used around a solid-fuel appliance on a marine vessel?

Possible components include a compatible vermiculite or high-temperature board, correctly sized rope gasket, rigid fire cement for suitable joints and an approved insulated chimney. The complete arrangement must follow the appliance manufacturer's marine instructions and the standard, code or examination scheme applicable to the vessel.

Can flue wrap replace an insulated marine chimney?

No. A wrap can insulate a compatible flue only where the design permits it. It does not convert ordinary single-wall pipe into a tested twin-wall chimney or establish the required clearance through a deck, roof or combustible lining.

What rope size is required for a marine heating appliance?

Use the appliance manufacturer's specification or match the original gasket and cleaned groove. The rope should seal evenly without stretching and must not be so large that the door or latch cannot close correctly.

Should I use silicone or fire cement on a flue joint?

Silicone remains flexible but is limited to 315°C. Black Fire Cement is rigid and rated to 1250°C. Select from the measured joint temperature, movement and flue manufacturer's specified jointing method; neither is universally interchangeable.

Can HRS sealant be used as a flexible expansion joint?

Do not assume that it remains elastomeric after curing. HRS is a high-temperature rigid sealing compound. Use a gasket or joint system specifically designed for the expected movement where flexibility is required.

Is HT Fireboard an A-class marine bulkhead?

No. Its A1 classification concerns reaction to fire under EN 13501-1. A marine A-class or B-class division is a complete assembly tested and approved with defined framing, insulation, joints and fixings.

Does the HRS railway fire certificate provide marine approval?

No. EN 45545-2 applies to railway vehicles. Marine installations governed by SOLAS or national rules may require IMO FTP testing and flag-state or recognised type approval for the exact product and assembly.

Can biosoluble or ceramic fibre blanket be used in an engine room?

It may form part of a designed insulation system if temperature, thickness, containment, fixings and exposure are suitable. Protect it against oil, fuel, moisture, gas velocity and mechanical damage, and confirm any required marine approval.

Does a 1200°C blanket mean the aluminium foil also withstands 1200°C?

No. The fibre and facing are different components. The exposed foil, adhesive or laminate may have a much lower limit. Obtain the facing data and apply the lowest relevant continuous temperature to the construction.

Can basalt tape be wrapped around a marine engine exhaust?

Only on a compatible dry exhaust where the engine or exhaust manufacturer permits wrapping. Check metal temperature, expansion, supports and inspection access. Do not apply it to a wet exhaust hose or water-injected component without specific approval.

What is the difference between exhaust insulation and a heat shield?

Insulation reduces heat flow from the hot component, while a shield intercepts radiant heat and normally includes a controlled air gap. Either can increase temperature elsewhere, so the complete geometry, ventilation and surface-temperature target must be assessed.

Can refractory castable repair a marine boiler?

It can repair a compatible refractory lining after the damage cause, anchors and substrate have been assessed. It must not be used to conceal damaged tubes, shell, burner components or other pressure and safety-critical parts.

Why is controlled dry-out required after a refractory repair?

Castable and mortar retain installation moisture. Heating a fresh repair too quickly can turn that water into pressurised steam, leading to cracks or explosive loss of material. Set the drying and heat-up stages from the product instructions, repair geometry and equipment manufacturer's start-up limits.

Can coated cloth make a fire- or smoke-tight marine barrier?

Only if the complete barrier, seams, supports and penetrations have been tested and approved for that duty. A fabric's temperature or low-permeability claim alone does not establish integrity under a marine fire test.

Can White Pipe Jointing Compound be used in a marine fuel system?

Use it only for a listed medium within the stated pressure and temperature and where the approved piping specification permits it. The visible scope names water, natural gas, LPG and low-pressure steam; it does not establish suitability for petrol or diesel.

What causes insulation to fail on a vessel?

Common causes include water or oil contamination, vibration, chafe, loose fasteners, compressed fibre, foil damage, excessive temperature and unsealed edges. Corrosion or leakage beneath the insulation can also remain hidden until planned inspection.

How should marine insulation be inspected?

Check external temperature, seams, fasteners, cladding, staining, odour, wet areas and mechanical damage. Remove designated inspection sections to look for exhaust leakage, substrate corrosion and contamination beneath the insulation.

What information is needed to specify a marine thermal system?

Provide vessel type and use, survey regime, equipment manufacturer and model, fuel, dry or wet exhaust design, normal and maximum temperatures, target surface temperature, clearances, substrate, vibration, moisture and oil exposure, existing construction, required fire class and approval authority.