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Intumescent coating expanding into an insulating char (illustration)

Fire protection · Intumescent coatings

Intumescent coatings – slim fire protection that keeps steel visible

An intumescent coating looks like paint, but in a fire it swells up to dozens of times its thickness into a carbon char that insulates the steel. It is the preferred fire protection for exposed and architectural steel – and it can be applied in the factory, so steel arrives on site ready to erect.

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R30 – R120
Typical cellulosic ratings
thin-film coatings
Up to ≈ 50 ×
Expansion in fire
product-dependent
≈ 200 – 250 °C
Typical activation
reaction starts
Shop or site
Application
airless spray, brush, roller
Intumescent char (illustration)

How an intumescent coating works

The coating system has three layers: an anti-corrosion primer, the intumescent basecoat and a topcoat for colour and protection. When the coating is heated, chemical reactions release gases that blow the softened binder into a thick, foamed char. The char has very low thermal conductivity and slows the rise of steel temperature.

The required dry film thickness (DFT) is taken from the product's tested and assessed data for each member – using its section factor, the critical temperature and the required fire rating. Thin-film products cover cellulosic (building) fires; thick-film epoxy systems are made for the faster, hotter hydrocarbon fires of oil, gas and petrochemical plants.

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Intumescent coating types

Product-type pages with typical data – brand and listed system per specification.

Types

Three families of intumescent coatings

Typical properties – each brand's assessed data defines the actual thickness.

Water-basedinterior · low odour

Water-based

Low VOC, for dry interiors and occupied buildings – offices, schools, retail.

Epoxy (thick film)hydrocarbon · C5

Epoxy (thick film)

Hard, durable systems for oil & gas, LNG and offshore steel – hydrocarbon and jet fire.

規格とコンプライアンス

Standards for intumescent coatings

Most often specified in our export markets.

Europe

  • EN 13381-8Test methods for reactive protection applied to steel members
  • EAD 350402-00-1106European assessment of reactive coatings (ETA / CE marking)
  • EN 1363-2Hydrocarbon fire curve
Europeの規格一覧 →

United States

  • UL 263 · ASTM E119Fire resistance of building construction (UL design listings)
  • UL 1709Rapid-rise hydrocarbon fire for structural steel
  • ISO 22899-1Jet fire resistance
United Statesの規格一覧 →

Australia & New Zealand

  • AS 1530.4 · AS 4100Fire-resistance tests; steel fire design
  • AS 4312 / ISO 12944Corrosivity categories for the coating system
Australia & New Zealandの規格一覧 →

参考用の概要です――プロジェクト仕様書、採用される基準の版、所轄官庁の判断が優先されます。

World Steel painting shop

Fire protection applied in the factory

World Steel blasts the steel to the specified surface grade, applies a compatible primer and the intumescent basecoat to the fire engineer's thickness schedule, then records the dry film thickness of each member in the coating report. Members are packed with protection at lifting points and supports; a touch-up kit and procedure travel with the shipment. See fire protection for structural steel.

Coated steel members (illustration)

Advantages and limitations

Is an intumescent coating right for your steel?

Advantages
AdvantageWhy it matters
Slim and decorativeThe steel's shape stays visible – ideal for architectural steel
Off-site applicationFewer site trades; steel arrives protected
Light weightNo extra load on the structure
Covers complex detailsConnections, cellular beams and hollow sections

FAQ

よくある質問

How thick is an intumescent coating?

Typically from a few tenths of a millimetre to a few millimetres of dry film for building fires – set member by member from the product's assessed data.

Can intumescent coatings be used outdoors?

Some products are approved for exterior or semi-exposed use with a specific topcoat; epoxy systems are made for harsh exterior and offshore conditions.

Is the coating applied in the factory or on site?

Both are possible. Factory application gives better control of thickness and saves site time; damaged areas are touched up after erection.

How is the coating checked?

Dry film thickness is measured on each member and recorded against the schedule; the inspector compares it with the required thickness.

Steel delivered with its fire protection

Send the member schedule and fire ratings – we quote steel and intumescent coating together.

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