Superheater TUBES are subjected to the most severe combination of STRESS, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be USED at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr.

FAILURES in superheater tubes may arise from :

1. Prior fabrication history
2. Faulty heat treatment
3. Consequences of welding
4. Overheating of the tube metal
5. Gas-side corrosion
6. Stress corrosion (AUSTENITIC steels).

Superheater tubes are subjected to the most severe combination of stress, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be used at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr.

Failures in superheater tubes may arise from :