screw for bronze pump 1

[silvana0098]

Hi
We design an water pump for use in marine environment with high Cl content.
Casing materials was Al/Bronze. However we use Stainless steel for screws, after 2 month it's screws were completely corroded.
I think bronze /silicon screws can't be used in this application because of their poor strength.
I want to help me to chose the best materials which was not only has corrosion resistance but also has high strength.

thank you all

 

[EdStainless]

I would use Monel hardware.


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Plymouth Tube

 

[MikeHalloran]

You could use SS screws if you isolate them from the AlBr with plastic sleeves and washers, but then you're faced with another material selection problem, finding the right plastic.

There are almost an infinite number of bronzes available, some of which are commonly made into screws, and some of which are quite strong.

Now you have to engineer the pump you designed in order to find out how strong the screws have to be, then you can figure out how large the screws should be and which alloys would be appropriate.

For informatiion about coppermetal alloys, start with the CDA at copper.org.



Mike Halloran
Pembroke Pines, FL, USA

 

[stevenal]

Was the stainless actually coroded away, or simply discolored?

 

[EdStainless]

My fear is that going to higher alloy SS will cause local corrosion of the AlBrz.
Monel is not that different galvanically and I have used Monel hardware in AlBrz and NAB pumps for many years.

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Plymouth Tube

 

[silvana0098]

Hi
thanks for your advises
what about duplex stainless steel screws? for instance, 2025!!
are monel screw is available? and wide spread?

 

[cloa]

Where are you located silvanna?

 

[silvana0098]

Persian Gulf /Iran

 

[EdStainless]

Monel is the most traditional alloy for seawater service.
I have seen boat propeller hardware in Monel.
I would guess that it would be easier to find a high alloy duplex (2205 is not good enough).

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Plymouth Tube