SS Selection for Hot Water Storage w/ Well Water
SS Selection for Hot Water Storage w/ Well Water
(OP)
Hi, I'm trying to decide if my company needs to step up to 316 grade stainless from 304 for our future direct gas fired heating system.
The system will be operating at 170-190 deg F with city water that has a variable 100-150 ppm chloride content (lake/stream versus well water seasonally)
I understand that 304 would be stable with this chloride count below 140 deg F, but some tank manufacturers have been warning us that we'll need to use 316 to avoid nasty things like stress corrosion cracking etc.
I'm mostly concerned about the 20,000 gallon storage tank we'll be using to store waste heat from other process equipment... during the day the water will be fairly stagnant which will affect the corrosion kinetics / diffusion, correct?
Any help would be appreciated. I'm the only engineer here so it's fallen upon me to nitpick details like this plus I'm fairly ignorant when it comes to corrosion, but I'm picking it up!
Thanks.
The system will be operating at 170-190 deg F with city water that has a variable 100-150 ppm chloride content (lake/stream versus well water seasonally)
I understand that 304 would be stable with this chloride count below 140 deg F, but some tank manufacturers have been warning us that we'll need to use 316 to avoid nasty things like stress corrosion cracking etc.
I'm mostly concerned about the 20,000 gallon storage tank we'll be using to store waste heat from other process equipment... during the day the water will be fairly stagnant which will affect the corrosion kinetics / diffusion, correct?
Any help would be appreciated. I'm the only engineer here so it's fallen upon me to nitpick details like this plus I'm fairly ignorant when it comes to corrosion, but I'm picking it up!
Thanks.





RE: SS Selection for Hot Water Storage w/ Well Water
I would suggest that you look at other alloys.
439 is one option. It is a ferritic alloy that has about the same pitting resistance (slightly better) as 304. It is immune to chloride SCC. This has been used for hot water tanks for years.
The other option would be the lean duplex LDX2101 or AL2003. The LDX2101 is slightly better than 304 and the AL2003 is better than 316. Both alloys are highly resistant to CSCC. Both alloys are also significantly stronger than 304 or 316 and would allow you to use thinner walls for the tank. This could result in saving money on the project.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: SS Selection for Hot Water Storage w/ Well Water
I'll take your suggestion on the AL2003 and research into it alittle more before contacting my suppliers...
Do you think we could get away with using 316 in the heaters where the flow is somewhat higher? (or is that only for crevice corrorsion?)
Thanks alot.
RE: SS Selection for Hot Water Storage w/ Well Water
What is the heat source?
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: SS Selection for Hot Water Storage w/ Well Water
439 will not SCC, but may pit. Before 2003 and 2101, the alloy of choice was 442. This is essentially 439 plus 2% Mo.It's very hard to find. If you cannot find 2003 or 2101 use 2205.
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: SS Selection for Hot Water Storage w/ Well Water
Now the supports for the packing directly above the incoming hot gas will have the highest heat flux. Actual water temperature will be in the 190 deg F range once the system has achieved steady state.
The tank will run with a recycle through the burners to keep it at >70% capacity and above 185 deg F.
Should we be considering a synthetic tank? I know there are some pretty slick polymers out there... but this needs to last 15-20 years in an external environment, although aluminum sheeting over the insulation might eliminate UV problems.
RE: SS Selection for Hot Water Storage w/ Well Water
I would suggest staying with duplex stainless for the rest of the tank.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: SS Selection for Hot Water Storage w/ Well Water
Here are a couple that are using duplex currently.
Albion - UK
Andrews/SOLARFlo - UK
TriangleTube/PhaseIII