Despite Preventive Measures, Damage Due To Moisture Impingement Has B

1.	Despite Preventive Measures, Damage Due To Moisture Impingement Has Been Found, In Certain Cases, In The Shield And Beyond. Why?
Answer» Shields are designed and fabricated on the basis of predicted range of steam/water quantities impacting the blades at specific angles. Now if the OPERATING conditions deviate significantly from design parameters then the EROSION damage will occur. And in some cases it may GO beyond NOMINAL erosion wear and WARRANT repair. Also the corrosion of casing can occur due to blockage/clogging of water drains or extraction thereby forcing the water back into the casing. If this condensate water is carried over to steam path and impacts the blade, thermal-fatigue failure can occur within a short period.

Despite Preventive Measures, Damage Due To Moisture Impingement Has Been Found, In Certain Cases, In The Shield And Beyond. Why?

Answer»

Shields are designed and fabricated on the basis of predicted range of steam/water quantities impacting the blades at specific angles.
Now if the OPERATING conditions deviate significantly from design parameters then the EROSION damage will occur. And in some cases it may GO beyond NOMINAL erosion wear and WARRANT repair.
Also the corrosion of casing can occur due to blockage/clogging of water drains or extraction thereby forcing the water back into the casing. If this condensate water is carried over to steam path and impacts the blade, thermal-fatigue failure can occur within a short period.