Microporous Insulation for Torpedo Ladles

Between the blast furnace and the steel shop, hot metal rides in a torpedo ladle — a 300 to 500 tonne bottle-shaped vessel that has to keep iron at pouring temperature across what is often a long and uneven journey. Heat lost in transit does not come back. The converter pays for it with more oxygen, a worse scrap ratio, and a tighter window for desulphurisation. A nano microporous backup layer inside the torpedo shell is one of the highest-leverage insulation upgrades a steel plant can make.

What Transit Heat Loss Costs

Every degree the hot metal loses on the way to the converter has to be replaced in the steelmaking step. That means more oxygen blowing, less cold scrap added per heat, and higher refractory wear in the converter. Cooler metal also hurts desulphurisation, because the reagent reactions that remove sulphur work better at higher temperatures. In field references for nanoporous backup linings, keeping the metal hotter in transit is consistently reported to arrive at the converter measurably warmer than with a conventional insulating-brick lining.

How the Torpedo Ladle Is Lined

The nano microporous board is installed against the torpedo shell on the inner wall, then the firebrick working lining is laid over it. This replaces the thicker conventional insulating layer that would otherwise be needed to reach the same thermal resistance.

Clean the shell and prepare the inner wall.
Fit microporous boards against the shell, trimming to the curved profile.
Install the firebrick working lining over the boards.
Use flexible sheet or pre-formed shapes on the dished ends where geometry is tight.

The Payoff

Lower heat loss during hot-metal transport, so the metal arrives hotter.
A thinner lining profile, which increases usable torpedo capacity — typically on the order of 5% for the same shell.
Lower converter energy demand for the same hot-metal temperature.
Better desulphurisation conditions, since reagent efficiency improves with hotter metal.

The capacity gain and the energy saving compound each other: more metal carried per trip, and less energy spent heating it back up. That is why torpedo-ladle insulation is often justified on energy alone, with the desulphurisation benefit treated as a bonus.

Board Selection for Torpedo Ladles

The backup layer runs behind the firebrick, so its duty temperature is the interface temperature between brick and board, not the hot-metal temperature. Grade 1000 (1000 °C) is the standard grade; Grade 1100 (1100 °C) covers designs where the board sits closer to the hot face. Thickness is confirmed by layer-by-layer thermal calculation.

Property	Value
Grades	Grade 1000 (1000 °C) / Grade 1100 (1100 °C)
Density	220–280 kg/m³
Thermal conductivity, 600 °C	0.028 W/m·K
Form	Rigid board, flexible sheet, arc-shaped, custom-shaped

For the curved ends of a torpedo ladle, arc-shaped and custom-shaped boards cut to the vessel profile eliminate the heat-leaking gaps that flat boards leave on a radius.

Recommended products for this application: arc-shaped boards and custom-shaped boards for the dished ends, plus standard boards for the barrel.

Frequently Asked Questions

How much hotter does the metal arrive?

Field references for nanoporous backup layers in hot-metal transport report the metal arriving at the converter measurably warmer than with conventional insulation, on the order of tens of degrees. The exact figure depends on the original lining, the journey length, and the ambient conditions — which is why we size the layer with a thermal calculation for your specific route rather than quoting a one-size number.

Will the board survive the loading shock?

The board sits behind the firebrick and is protected from direct metal impact. The microporous matrix is dimensionally stable at the interface temperatures it sees, and the working brick absorbs the mechanical load.

Does a thinner lining reduce shell protection?

No — the board raises the thermal resistance of the wall, so the shell actually runs cooler at the same metal temperature, which is better for shell life and safety.

Do the curved ends need special boards?

Yes. The dished ends of a torpedo ladle are a tight radius, and flat board leaves gaps there. Arc-shaped and custom-shaped boards cut to the profile close those gaps, which is where most of the heat escapes on a poorly fitted lining.

Moving hot metal further without losing the heat? Ask our engineers for a torpedo-ladle-specific board and thickness calculation, or review our steel ladle insulation for the downstream vessel. Contact us to get started.