High Temperature Pump Body Material 2

[Metcorr]

For a heat recovery pump, where the temperature is expected t rise around 800 C, we use stainless steel 316 casting for pumps body. Are there any better material such a ss310 casting that can be used?

 

[metengr]

Metcorr;
Why are you asking if there is a better material? Have you had problems from leaks caused by creep deformation?

 

[Metcorr]

Yes we have seen some sign of deformation in 316 casing as the pump is some times operated around 800C. Hence, there is a suggestion to upgrade the casing with SS 310. In my opinion it may not be quite necessary as 316 casting should be okay at the above mentioned emperature.

 

[metengr]

Metcorr;
If this distortion is a chronic problem it could be that you need to thicken the case to reduce service stresses. The 316 ss exhibits oxidation resistance for high temperature use, but creep strength is another matter. Can you check the carbon content of the casting? It should meet the specification below for starters

ASTM A 351 either Grade CF-8M 0.08% C max, or it could be a CF-12M (316 ss) with higher carbon to 0.12%. I would hop your carbon content is close to 0.08%.

 

[Metcorr]

Thanks Metengr. But, just curious to know, are there pump casing made of SS 310? And what service temperatures they are usually recommended? I think up to 800C, SS 316 casing should be okay. Above 800C, SS 310 may be considered. Does that selection seems okay?

 

[metengr]

Metcorr;
Yes, you can have cast versions of 310 ss. There are cast versions of high temperature - heat resistant stainless steels like HH, HK, and so on.

 

[arunmrao]

Thanks metengr for recommending HK grade. As a foundryman I was feeling miserable that a higher alloy was not being recommended (business interests).

I have made some pump parts in HU too. Today I have an enquiry for HV castings.

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[davefitz]

modified 310 SS is called HR3C, much higher allowable stresses than 310 ss. welds are quite brittle though. See Sumitomo tech data

 

[EdStainless]

Well, I wish that my books were handy.
I would lean toward the HU grade. This is cast 825, with higher carbon for high temp strength. If you need to weld on it then use the CU lower carbon version. Even that one will have a lot higher strength than your 316.

 

[arunmrao]

Ed! Has the Ni price fallen so steeply? You are being very generous today in your recommendation.

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[EdStainless]

It hasn't fallen that much, but it looks stable in the mid $14/lb range.
When you want some corrosion resistance and high temp strength there are not a lot of good options. The other nice thing is that at ~40% Ni this alloy has pretty good CSCC resistance to go along with its strength and phase stability.