Esshete 1250 is a fully austenitic chromium-nickel steel with excellent high-temperature strength and good resistance to corrosion in boiler applications. The grade can be used at temperatures up to about 650°C (1200°F), it is easily fabricated and also characterized by:

• High strength in relation to other typical candidate austenitic alloys

• Very good resistance to steam and flue gas atmospheres

• Good structural stability at high temperatures

• Good weldability

Applications
The high creep strength of Esshete 1250, combined with its good resistance to steam and flue gas atmospheres, makes it a very suitable material for use in coal-fired boilers. The grade was developed in the United Kingdom in the 1960's, and the bulk of the material has been used in the UK power industry in 500 and 660 MW boilers.

The main application has been superheaters and reheaters operating at 570°C (1058°F), steam pressure 170 bar (superheaters) and 40 bar (reheaters). Typical metal temperature 600-700°C (1112-1292°F), in flue gas temperature 900-1200°C (1652-2192°F). The corrosion environment on the fireside in the UK boilers was historically very aggressive as the British coal has, typically a high chlorine content of up to 0.6%, sulphur at 1-2% and a high ash content of 20%.

Esshete 1250 has also been used successfully in superheaters in biomass boilers, burning various biofuels and producing steam at 580-540°C (1076-1004°F) at 60-200 bars pressure.

Trademark information: Esshete 1250 is a trademark owned by Corus