This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Corrosion Damage Mechanisms in the Utility Industry
J. L. Blough, Supervisor Metallurgical ServicesJ. L. Blough, Supervisor Metallurgical Services
FirstEnergy BETA Labs FirstEnergy BETA Labs 6670 Beta Drive 6670 Beta Drive Mayfield Village, Ohio 44143Mayfield Village, Ohio 44143
Utility Industry involves most Corrosion and Mechanical Damage Modes • Room Temperature to 2000 °F• Air, acidic, basic, microbiological to molten salts• brittle fracture, fatigue, creep and creep fatigue
Most metals and numerous non-metallic materials of construction• Ferritic steel• Austenitic, ferritic and martensitic stainless
steels• Nickel base alloys• Copper base alloys• Titanium alloys• Cast iron to high alloy castings• Weld overlays
Fabrication of all the above alloys 5
FOSSIL-FIRED POWER PLANTS
Boiler tube failures (BTF) primary cause of lost availability
3% lost availability 80% of all BTF result in an outage ~3 days 3 days ~$ 3 million for replacement power In summer 1000MW plant 12 million
Uniform or General AttackGalvanic or Two Metal CorrosionCrevice CorrosionPitting CorrosionIntergranular CorrosionSelective Leaching or DealloyingFlow Assisted CorrosionEnvironmental Cracking
11
DAMAGE MECHANISM TO ROOT CAUSE DETERMINATION
Determine the damage mechanism- Do Not Guess Know the variables that effect the damage
mechanism- do things add upWork with the plant to explain the mechanism and
variable effecting the mechanism• Operations, Maintenance, Design• Stress, temperature, cycles, pH, water treatment, oxygen,
down time, fabrication method, operating hours Root Cause determination must be determined to
avoid a repeat failure
EXAMPLES
FIGURE 11, TYPICAL CROSS SECTION MICROSTRUCTURES JUST BELOW THE FRACTURE FRONT. ABUNDANT “LIGHTENING-BOLT” CRACKING TYPICAL OF STRESS CORROSION STARTING ON THE OD,