Grade/type of Ni-hard for ash slurry line bends 1

[snibril]

Calling any gurus in the area of slurry piping or wear resistant materials!

I'm getting some Ni-hard bends cast for re-routing our ash slurry line, but need some advice on the grade of Ni-hard material to specify. Pipework is approx. 330 diameter, flow approx. 220L/s. The bends will be coupled to cement-lined ductile iron pipe (otherwise socketed) running in a concrete box-conduit.

We have some Ni-hard bends on our coal mill discharge pipework of spec ASTM A532 Grade 1 Type 1, but I assume that our pulverised coal is somewhat less abrasive than chunks of bottom ash and a higher grade would be required. The equivalent British Standard appears to be BS4244 (grades 2B, 2C 2E etc.). However, I also note that the harder the material, the more brittle it'll be.

Is there a grade that is typically used for ash slurry? or is there some means of determining the abrasiveness of the slurry to indicate the hardness required?

Any comments/suggestions would be greatly appreciated.

Cheers

 

[gieter]

We cast a lot of bends and branches for the dredging industry. The standard material here is Ni-Hard 4. This material combines a good abrassion resistance for slurries with a good ductility (for white cast irons anyway). This means that it can be casted in more complex chapes than Ni-Hard 1 and 2, and other abrasion resistant white cast irons. The thing you need to see to is that your castings are heat-treated. In the as-cast condition Ni-Hard 4 has an austenitic matrix. Only after heat-treatment the austenite is transformed to martensite and a little bainite, giving the good abrasion resistance. Not all foundries do a heat treat!
A good reference for Ni-Hard is a publication from the Nickel Development Institute, publication 11 017 (1996). You can ask for it on their website

http://www.nidi.org.

 

[snibril]

Thanks. I'll look into it.