Causes of pump casing damage??
Causes of pump casing damage??
(OP)
The casings on two of our pumps are suffering from damage.
These two pumps are horiztonal split case, double suction with end discharge. They were manufactured by Worthington-Dresser in Germany in 1991. They are about 1000 HP, with Ductile Iron casings and bronze impellers.
The pumps are used with both raw and treated water.
Any ideas on the CAUSE? Has anybody else had similar problems with Worthington Pumps bought at the same time (1991)?
[img http://img454.imageshack.us/img454/5209/p81107051vm.jpg]
[img http://img454.imageshack.us/img454/3249/p81107210dv.jpg]
[img http://img454.imageshack.us/img454/9646/p81107250bi.jpg]
These two pumps are horiztonal split case, double suction with end discharge. They were manufactured by Worthington-Dresser in Germany in 1991. They are about 1000 HP, with Ductile Iron casings and bronze impellers.
The pumps are used with both raw and treated water.
Any ideas on the CAUSE? Has anybody else had similar problems with Worthington Pumps bought at the same time (1991)?
[img http://img454.imageshack.us/img454/5209/p81107051vm.jpg]
[img http://img454.imageshack.us/img454/3249/p81107210dv.jpg]
[img http://img454.imageshack.us/img454/9646/p81107250bi.jpg]





RE: Causes of pump casing damage??
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RE: Causes of pump casing damage??
What is the PH of the water? The bronze impeller looks ok in the picture, is it?
Regards checman
RE: Causes of pump casing damage??
As for the PH, when we are using the pumps for treated water, the PH can get as high as 8.8 to 9.
It's been reported that there is sometimes sand in the water. Could sand or silt have caused this damage?
RE: Causes of pump casing damage??
If you look closely at the photo's you can see corrosion in the stuffing boxes and under the wear ring locations, there is no flow in these areas so no erosion has taken place.
My suggestion is all bronze pumps for this application.
Naresuan University
Phitsanulok
Thailand
RE: Causes of pump casing damage??
http://www.belzona.com
RE: Causes of pump casing damage??
RE: Causes of pump casing damage??
There can be various reasons for this corrosion : Gas entrainment in water, cavitation, operation away from BEP.
Damage is less evident on impeller because of it's superior metallurgy.
RE: Causes of pump casing damage??
Yes, the pump is on intermittent mode and is not constantly used.
What are some of the causes of the erosion corrosion? Possibly the sand?
Artisi: You mentioned "fines" in the water? What do you mean by "fines"?
RE: Causes of pump casing damage??
There should not be much difference in corrosion advantage between cast and ductile iron. Plus, at the same time the pump was manufactured (1991), many companies started to have their casings casted in other countries, such as China and India.
Could it be that there was a problem during the manufacturing of the ductile iron casing during that specific time?
RE: Causes of pump casing damage??
Naresuan University
Phitsanulok
Thailand
RE: Causes of pump casing damage??
If the pump is on intermittent mode as suggested and the liquid is not treated with chemicals that prevents/reduces corrosion you cannot escape from having corrosion over time unless your material selected is a Corrosion Resistant Alloy.
RE: Causes of pump casing damage??
Which leds us to suspect that it not only could be a combination of the sand/silt, but also a manufacturing/casting defect with this particular ductile iron pump?
RE: Causes of pump casing damage??
Corrosion is a chemical reaction causing loss of metal while erosion results from mostly abrasives (like sand) in the liquid. Under high velocity this creates a situation that can be likened to sand blasting. The result is also loss of metal over time."
In a situation where corosion is a problem, any entrained fines (solids) can very quickly cause major damage as the corosion is always a lot less abrasive resistant than the parent metal. In extreme conditions a pump unit can be totally destroyed in very short order.
Naresuan University
Phitsanulok
Thailand
RE: Causes of pump casing damage??
Naresuan University
Phitsanulok
Thailand
RE: Causes of pump casing damage??
Your case seems to be a case of erosion corrosion,where the sand particles which are extremely abrasive have accelerated the wear.
RE: Causes of pump casing damage??
I don't think it's a problem with all ductile iron casings. I think it might be a problem specifically with this one pump. The metallurgist test is a good suggestion.