Structural Fireproofing

Quick pick (TL;DR)

Hydrocarbon plant (pool/jet fire) → test to UL 1709, not the cellulosic ASTM E119 curve.
Cementitious spray: cheap, robust, for structures & skirts.
Intumescent epoxy: thin, durable, architectural & offshore.
Thickness comes from the member's section factor Hp/A and the required rating (30–180 min) at critical steel temperature ~ 538 °C.

Step 1 — Fire type & test curve

Fire type	Test standard	Where
Cellulosic	ASTM E119 / BS 476	Buildings
Hydrocarbon pool	UL 1709	Process plant
Jet fire	ISO 22899	High-pressure / offshore

Step 2 — Choose the system

System	Best for	Notes
Cementitious spray	Columns, skirts, racks	Low cost, thick, mesh
Intumescent epoxy	Architectural / offshore	Thin, durable, costly
Concrete encasement	Blast + fire	Heavy
Board / blanket	Retrofit / complex	Dry, fast

Step 3 — Thickness from section factor

Pipe-rack column, 2 h HC

Given fire = hydrocarbon pool (UL 1709) rating = 120 min critical steel temp Tc = 538 °C Step 1 — Section factor heated perimeter Hp = 1.45 m steel area A = 0.0121 m² Hp/A = 1.45 / 0.0121 = 120 /m Step 2 — Read chart UL 1709 chart, 120 min, Hp/A 120, Tc 538 °C → intumescent DFT ≈ 5–7 mm (per system) Rule higher Hp/A (thinner steel) → more thickness

Hp/A shows heating speed — high Hp/A needs more thickness; final value from certified chart.

Section-factor calculator (Hp/A)

How fast the member heats

Hp/A = heated perimeter ÷ steel area — higher = heats faster.

Hp (m)

Steel area A (m²)

Rating

Hp/A drives thickness — actual value from the certified UL 1709 chart.

Common mistakes

ASTM E119 data in a hydrocarbon plant.
Ignoring section factor.
No durable topcoat outdoors.

Requisition & datasheet

Fire type, rating, Tc, member, Hp/A.
System, thickness, mesh, approval.

Frequently asked questions

What should I know about Structural Fireproofing?

Hydrocarbon plant (pool/jet fire) → test to UL 1709, not the cellulosic ASTM E119 curve. Cementitious spray: cheap, robust, for structures & skirts. Intumescent epoxy: thin, durable, architectural & offshore. Thickness comes from the member's section factor Hp/A and the required rating (30–180 min) at critical steel temperature ~ 538 °C.

Which standards or codes apply?

UL 1709 (hydrocarbon rapid-rise), ASTM E119 / BS 476 (cellulosic), ISO 22899 (jet fire), API 2218 (fireproofing practices).

Standards — UL 1709; ASTM E119 / BS 476; ISO 22899; API 2218.