is it high risk?

[chemical321]

i work in a power plant (1600MW: 4*150MW)
in the past we did chemical cleaning only for water wall tubes beacuse the risk of turbine blade damage.
at this time in the water wall tubes, deposit is 350 gr/m2. but in the supper heater tubes, it is 450 gr/m2.
we have the base 400gr/m2 (in water wall tubes) for chemical cleaning. and in overhaul we don't have decision for chemical cleaning,

IS IT HIGH RISK? WHY?

 

[metengr]

Yes, this type of internal deposit in the boiler waterwall circuit means the potential for elevated tube metal temperature resulting in corrosion fatigue, thermal/mechanical fatigue damage and increased risk of underdeposit corrosion.

EPRI, which is an electric ultility research and application organization, recommends chemical cleaning of power boilers at or above 160 grams per m[sup]2[/sup] for waterwall tubes.

 

[Duwe6]

metengr missed "Creep" due to the elevated temp, with associated creep corrosion, and creep corrosion cracking. Bottom line: tubes with internal deposits get hotter than their design allowed for, so they fail prematurely. Rapidly degrading tubes require more often and more through instections -- expensive. They reach their End-of-Uesful-Life much seener -- expensive. If not adequately inspected and tracked, these tubes fail prior to being replaced. One catastrophic superheat tube blowout can, and usually does force a boiler shutdown. Sudden, unexpected loss of 150MW of power is expensive.

Multiple added major expenses, probable catastrophic tube failures: sounds HIGH RISK to me.