How calculate corrosion allowance of HYDRAULIC TURBINE
How calculate corrosion allowance of HYDRAULIC TURBINE
(OP)
How calculate corrosion allowance of HYDRAULIC TURBINE.
The information I have
1. Material is EN-JS1030 (QT400-15)Spheroidal graphite cast iron
2. Fluid is water (Chloride=220 ppm)

Thank You
The information I have
1. Material is EN-JS1030 (QT400-15)Spheroidal graphite cast iron
2. Fluid is water (Chloride=220 ppm)

Thank You





RE: How calculate corrosion allowance of HYDRAULIC TURBINE
it looks it is painted inside too, can you confirm?
bye
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
even knowing pH, oxygen, water origin, etc., you will have difficulties in calculating any corrosion rate and also in concluding that cast iron is OK for the service in absence of coating...
In my opinion, only the coating provides the resistance, I would go for usual 3mm corrosion allowance in addition to the existant coating material, but whatever corrosion allowance is, it will probably not sustain the conditions without the coating.
once the coating is off, you may probably experience severe corrosion of the cast iron by water with unknown characteristics.
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
Sand is your worst enemy; chlorides not necessarily so much if temperatures are low. But it's a function of the overall fluid makeup and operating conditions. Wear in hydro turbines (and pumps) will be highly localized, so a stock corrosion allowance is not really a useful approach.
Run it and see is the best answer I can give; predicting is a mug's game. Past performance in the same environment (if there is any data) is your best guide.
Personally I would not use cast iron for anything at all critical (and I've built a fair few hydro turbines). I also learned from designers that cavitation (the classic wear mode in turbines) is best combatted by design rather than by barriers. Obviously abrasive environments are another matter altogether. Coatings won't buy you any wear protection.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
For cast iron runners, the best option would be to protect the suction side with epoxy based anti cavitation paint or protective coating, though they're hard to apply when the runners are salvaged during the outage.
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
Stainless steel overlay on cast steel runners is a widely used approach, but 309/L is inferior to a single layer only of 308/L with no butter later. This was learned by trial and error and by cavitation testing. The micromechanism for cavitation resistance, strain-induced martensite transformation (which happens in service) was discovered later by Fihey et al at IREQ in Québec and led to the development of a commercial product marketed by Stoody. This welding alloy is similar to stainless steel, but substitutes cobalt for most of the nickel.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
RE: How calculate corrosion allowance of HYDRAULIC TURBINE
I'm very well aware of this anti cavitation alloys(including manufacturer's brands) which are applied for hydro turbines, as well as the problems associated with it. In fact had dealt with quite a few runners involving such anti cavitation alloys in the past.
Thanks.
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299