INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!

Talk With Other Members
Be Notified Of Responses
To Your Posts
Keyword Search
One-Click Access To Your
Favorite Forums
Automated Signatures
On Your Posts
Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

LINK TO THIS FORUM!

Eng-Tips LinkedIn^® Group

Join our
LinkedIn^® Group!

Hook up with past and present colleagues and classmates quickly.

Partner With Us!

"Best Of Breed" Forums Add Stickiness To Your Site

(Download This Button Today!)

Feedback

"...This has been the MOST helpful forum that I have been a part of and I want to say thank you. The tips, tricks and helpful advice that you all contribute to have been lifesavers in many instances..."

More...

Geography

Where in the world do Eng-Tips members come from?

Click Here To Find Out!

Eng-Tips Shirts!

Get your
Eng-Tips Forums
SWAG here!

Home > Forums > Materials Engineers > Activities > Corrosion engineering Forum

Material choice for water pump impeller

Read More Threads Like This One

gmh265 (Mechanical)

17 May 11 23:40

Hey Guys,

I have been tasked with replacing the damaged impellers of a group of water/slurry pumps that are used in the mining industry. They do see a fair bit of nasty fluids including sea water.

The impellers are currently cast iron, and the failure mode is the impeller blades wear away. I was thinking a replacement of 1020 steel fully machined, however I have little experience in material selection, particularly when it comes to corrosion.

What am I overlooking here?

Stainless is not an option unfortunately.

cheers,

Joel

KENAT (Mechanical)

18 May 11 0:09

Why were they cast - is it a shape that will be difficult/costly to machine? (Though with modern multi axis machines that's a less common issue.) Would your volumes now preclude casting as a cost effective solution?

What finish was used originally, and are there any new surface treatments that might be better?

Not quite the same requirement but take a look at thread330-295440: Strong, hardenable, corrosion resstant steel? for ideas.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

EdStainless (Materials)

18 May 11 8:54

Often they use Ni-Resist for cast pump impellers.  This is a high Ni cast iron that has very good corrosion resistance and fair wear resistance.

What is the original producer offering you? If they are worn then you can't reverse engineer the blade shape.

Fabricated impellers are usually difficult.  Even if you can get the geometry correct they tend to have issues with fatigue at welds.

You should not use a plain steel.  If you really want better life then you need to look at alloys like 3CR12 or other straight Cr stainless grades.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

MikeHalloran (Mechanical)

18 May 11 10:51

1020 is definitely not the hot setup.

You need to do some industrial archaeology. Dig through the purchase records of the company until you find what material was originally specified for the pumps, and whatever was specified for the previous set of impellers.
You will probably find that the extant impellers are not generic 'cast iron', but a high tech abrasion resistant alloy that costs even more than stainless steel.

Whatever it is, work from there.

Mike Halloran
Pembroke Pines, FL, USA

rmw (Mechanical)

18 May 11 21:30

Nagle Pumps had a 28% Chrome hard iron impeller material that they used for slurry and mining pumps. Pretty doggoned tough stuff. I remember one nationally recognized pump repair company at a loss of what to do with it because they had never seen a CI impeller that hard.

rmw

Pumpsonly (Mechanical)

23 May 11 5:28

So your pumps see some thing more than just water..
Warman pumps used Ni-hard for their slurry pumps.

strider6 (Materials)

24 May 11 2:24

I agree that carbon steel is not an option and you should go at least to the Ni resist, or improve to higher alloy, but you should define better what you mean with "nasty fluid" if you want to make a good material selection

http://corrosionist.blogspot.com/2010/10/selecting-pump-for-seawater-service.html

hope this help

S

Corrosion Control

clay87 (Mechanical)

25 May 11 21:58

Erosion or Corrosion is main problem? You could always coat the impellers to improve the life of them.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Back To Forum

Back To Corrosion engineering