pump casting defects 1

[EagerLearner]

how can casting of the pump bowl failed? what could have caused this? can this be repaired if there are any defects?

I am new and want to understand.

 

[Artisi]

To answer your 3 questions:
1.Don't know
2.Again no idea
3.Maybe

You are a bit short on detail for any sensible answer.
What type of pump, what is the application, what type of failure what are the defects etc etc.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[DubMac]

Bad casting

 

[vpl]

Pictures of the failure help with the diagnosis.

Patricia Lougheed

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[micalbrch]

Yes, we need a picture and - apart from what Artisi wrote - also the material (grey cast iron? cast steel? stainless steel?).

 

[TenPenny]

How can a casting fail? It could be a bad casting, porosity, voids, cracks due to shrinkage from poorly desinged pattern, any number of things.

What could have caused this? Any number of things, you would really have to take a course on casting.

Can it be repaired? Depends on what the problem is, where is it is in the casting, what the material of the bowl is, etc.

 

[eyec]

it is not unusual to have imperfections in castings. to what extent and location of the imperfections can cause failure @ hydro, require extra machining, and even weld repair.

some may just be cosmetic. depends also on customer's requirements.

 

[EagerLearner]

Its a centrifugal submersible seawater lift pump on production for a new project.
These casing defects on impellers and bowls were only visible after machining.

The vendor has been using the same foundry for about 10 yrs and this is the second time it happen over a short period of time.

i attached the picture.

 

[DubMac]

good old fashioned porosity; happens all the time. A radiography test performed on the casting would have caught this.

If this is the first (or second) problem they've had in ten years just chalk it up to percentages and move ahead.

If these pumps are sea water lift, they may be nickel aluminum bronze?? Not the easiest alloy to pour.

If these pumps are super critical to you, then you should ask for (and pay for) radiography testing on the cast parts.

 

[Artisi]

Looking at the photo, which unfortunately is not all that clear, but it appears that the whole area could be riddled with porosity. You need further testing to check the casting.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[micalbrch]

That can be a critical area for annealing after casting. The foundry should know that but as you do not talk directly to the foundry you will most likely not hear the truth. Or the pattern is too old and worn out. But my tip is the annealing phase after casting.

 

[hydromech]

That is shrinkage porosity and a direct result of poor or incorrect filing. The foundry should have spotted this, but it is no surprise that they did not catch it. A bigger riser would sort the problem.

Another solution is a hotter melt, but then the material is more likely to take on hydrogen and you'll get gas porosity. Gas porosity is less of a problem. but ultimately it depends on the specification issued to the foundry.

 

[clay87]

Based on the limited info given and the photo, that looks like an AlBr or NiAlBr casting as mentioned above. These porosities are not uncommon for infrequently poured AlBr castings and are easily chased and weld repaired. Unfortunately, if the flanges and bores have been finish machined this will probably require weld buildup to all of the critical bores and faces due to heat-induced distortion of this material.

Porosities like this don't necessarily mean the part is junk. I suggest hydro-testing any pressure boundary parts.