Q. High temperature materials in Boilers?

A thin refractory layer between the shield and boiler tube is recommended in areas subject to moderate temperatures and levels of corrosive elements. This will serve to keep shield temperatures within reasonable limits.

A weld overlay at the inlet tubes is recommended for elevated to high temperatures and where large amounts of corrosive elements are present. Using Inconel 625 as a weld overlay is beneficial due to its corrosion resistance and close thermal expansion properties to carbon steel. Inconel 625 is also resistant to adverse effects of high temperature fluctuations.

Alloys T-1 and T-2 are ferritc stainless steels designed to offer good high temperature strength and corrosion resistance to about 1100°F (600°C). Alloys TB9 and TB12 also possess the same characteristics as well as good creep rupture properties. These alloys offer an alternative to austenitic stainless steels.