MOL Resistant Material

According to this, cast iron has excellent corrosion compatibility with calcium hydroxide.

So the mechanism of failure needs to be examined in greater depth.

Thanks . Well I was thinking on the lines that maybe a particular grade of CI is more effective. It does look like that the failure is due to errosion at spots where the vortises are formed!

Titanium also looked good, but I don't know the availability of pumps made with it. If the flow and pressure are moderate, maybe a plastic pump would work?

(Subsequent edit: A search on "titanium pumps" turned up some links, so probably worth investigating. Also answers a recent HBr question.)

But wont titanium go way out of budget! Plus there are availability issues with it, not to mention casting issues later!! :(

Might help: from http://www.johnson-pump.com/JPIndustry/AODD/TopAir.htm

We have successfilly used Sulzer model WPP pumps with casing material A747CB7Cu-2 and impellers of A532 IIIA for pumping MOL.

Hope this helps.

Hey thanks man!

So after how long do you guys need to replace the pumps now? And do these pumps run on a perpetual duty or is it intermediate running sort?

The pumps (one running, other installed spare) have been running 24/7 since first of April 2009 with no known problems. What concentration of MOL are you circulating?

Man its266kg per meter cube of water. The temperature is 92 C.

So the material and its performance sounds pretty good. How long did the original material last?

We don't know yet...it is a new pulp mill installation but this material has been successfully used in other slurry applications and we typically get 5 years or so life out of the pumps, many of them are in applications where we have up to 35% solids on a weight basis so you should be good to go.

Ahan.

Well its not pure MOL that we have at our place either. Part of teh problem is because of the errosion caused by grit. Its a CA(OH)2 producing site from CAO. Some of the stones don dissolve to we get perfect pump nightmare situation!