Abstract
Alloy 33 is a weld overlay material that has generated a lot of interest in the fossil boiler industry. The high chromium content of Alloy 33 has been shown to provide excellent corrosion protection in both waterwall and superheater/reheater tube applications. For waterwall applications, the corrosion resistance has been demonstrated in both laboratory and field tests conducted over the last 5 years. In addition to corrosion resistance, the Alloy 33 has also shown that it is also resistant to cracking (although no material is 100% immune). In the superheater/reheater, the use of spiral clad weld overlay tubes is able to provide resistance to excellent coal ash corrosion. Laboratory and field tests have shown Alloy 33 to have among the best corrosion resistance of all materials studied. The application of Alloy 33 is also easier than other more highly alloyed materials (such as FM-72) and is less expensive. As a result of these favorable experiences, Alloy 33 is now being used commercially to weld overlay both waterwall and superheater/reheater tubes on fossil boilers.
