Corrosion protection of pumps
07-27-2012, 05:24 PM,
#1
Corrosion protection of pumps
Hi all,

For pumps handling extreme grade salinated water; upto 700-800 ppm, what would you recommend for corrosion protection of pump casings and impellers:

cr2o3
Or
WCCoCr- HVOF sprayed
Or any other coating?

Regards

Shantanu

Reply
07-27-2012, 08:48 PM,
#2
RE: Corrosion protection of pumps
There are lots of coatings which can protect the pump casings from corrosion. The key is getting full density of the coating in order to prevent the saltwater from getting to the base metal. WCCoCr and Cr2O3 would only be necessary if you also have an abrasion problem as well.
Reply
07-30-2012, 05:15 PM,
#3
RE: Corrosion protection of pumps
More information needed.
What kind of pumps are you dealing with (most likely centrifugal, but it bears asking)?
What is the temperature of the process fluid (it makes a big difference)?
Are there solids in the process fluid? Any indication of abrasion (even fine particle)?
What are the pumps made of (most likely cast or ductile iron)?

Sealer is likely a good idea depending on the above. Even minimum porosity will lead to under coating corrosion and ultimately delamination in the case of most iron alloys in this type of solution.
Reply
07-30-2012, 07:13 PM,
#4
RE: Corrosion protection of pumps
(07-30-2012, 05:15 PM)MichiganMan Wrote: More information needed.
What kind of pumps are you dealing with (most likely centrifugal, but it bears asking)?
What is the temperature of the process fluid (it makes a big difference)?
Are there solids in the process fluid? Any indication of abrasion (even fine particle)?
What are the pumps made of (most likely cast or ductile iron)?

Sealer is likely a good idea depending on the above. Even minimum porosity will lead to under coating corrosion and ultimately delamination in the case of most iron alloys in this type of solution.

Dear Michiganman,

Pump type: centrifugal
Temp of process fluid: ambient
Solids in process fluids: NO
Pump MOC: Cast iron

Understanding that any porosity is unadvisable, HVOF then should be the ideal process....and what sealer would you recommend? Will a standard loctite be ok?

Shantanu

Reply
07-31-2012, 04:08 PM,
#5
RE: Corrosion protection of pumps
I'm a bit confused by the 700-800 ppm being referred to as "extreme grade". Perhaps this is (or will be) medical grade saline you are handling, or perhaps I am misinterpreting what you mean by 7-800 ppm? Typical saltwater from the ocean is more than 35000 ppm, so maybe I am not using consistent units of measure compared to your statements. If it is a medical (or even a food grade) application for the water, then I would suggest being careful to choose a sealer that will not leech chemical into the process over time (something with NSF 61 or similar approval).

At any rate, at ambient temps most of the common organic sealers will do fine in a saline environment and you can easily determine it viability for your application by consulting the item's product data sheet. Frankly, I would be more likely to use a ceramic filled composite coating (probably epoxy based) for this application than a TSC, because with no abrasion in the evironment it would last forever and give a smoother finish offering better pump efficiency and it would cost a fraction of the price.

I haven't considered the resistance to corrosion in a saline environment of the alloys you are thinking of here, so I can't say I would recommend either specifically, but I have used both in immersion environments before, and both do just fine. Even with the HVOF I would recommend use of a sealer though, otherwise one tiny pore can cause a whole lot of damage to the integrity of the coating (a phenomenon similar to crevice corroion takes place beneath the coating and it gets real bad real fast sometimes).
Reply
08-01-2012, 06:37 PM, (This post was last modified: 08-01-2012, 06:56 PM by k09.)
#6
RE: Corrosion protection of pumps
We have sprayed many pump sleeves with densified Chrome Oxide coating which has worked very well. To check the endurance of the coating in corrosive saline conditions we have validated our coatings in Salt spray test. However I have also been told that a dense WC-Co-Cr coatings work equally well in such corrosive conditions.

Regards
K09
Reply




Possibly Related Threads…
Thread Author Replies Views Last Post
Lightning Aluminum Foil wrapping as corrosion protection instead of coating LouisRichter 2 4,092 09-22-2017, 11:07 AM
Last Post: madan.pal
  Corrosion protection plasmajet1990 1 2,017 09-25-2015, 10:52 AM
Last Post: Joris Kraak
  Big Screw pumps repair HVoilF 9 11,590 07-01-2011, 01:58 PM
Last Post: mleonardo
  Corrosion Protection Chris Wheatley 5 6,070 06-04-2009, 07:16 PM
Last Post: djewell
Shy Repair to HD vertical pumps [split] HVoilF 1 4,436 05-13-2009, 03:25 AM
Last Post: Gordon
  repairing slurry pumps sutech 1 3,465 09-23-2008, 09:26 PM
Last Post: TurbineRepair
  Copper protection against high temperature corrosion hgjor 1 6,029 05-10-2008, 02:07 PM
Last Post: Gordon
  corrosion protection of potable water pipelines basakglkn 1 4,902 11-29-2007, 06:47 PM
Last Post: Gordon
  Dissimilar Metal Corrosion Protection BELLAMARE 4 24,619 11-13-2007, 10:41 PM
Last Post: ECK ECK
  Corrosion protection Yanni 1 4,689 12-05-2006, 06:03 PM
Last Post: Gordon



Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd