valve components material

[helpyou]

HI,

I have a proposal for valve components material for butterfly valve which i need to replace. application is seawater , max pressure 10 bar , temperature ambient (0-60C)

these are the material options:

Body uctile iron with EPDM internal liner
Shaft: dry shaft with SS 420
Disc: Ebonite coated Ductile Iron
Seat: EPDM

Are these good material options for my application. when it comes to strength & corrosion resistance. Can anyone advise from experience please?

Thank you

 

[gerhardl]

Hi helpyou,

OK under circumstances but depending on construction details.

And a reminder: seawater is not only one thing, temperature, salt and chemical composition in general, and temperature, will vary over the world. Use of the valve and particle content might give extra wear.

Size will influence on what are practical and optimal solutions.

Have a look on what is usually solutions for instance for fishfarming in seawater (all plastic), offshore NACE specifications (special materials and requirements), and for large valves (1000 mm plus) for seawater lines for cooling, with rubber clad discs(power plants/other).

 

[helpyou]

Hi gerhardl,

Thank you for your reply. Really helpful. What you mentioned about the offshore NACE specifications. Do you know how to get them? Are they available for free in the internet or is it something i have to buy ?

Thank you

 

[gerhardl]

Hi again,

Try to search this forum and the net. Complete specifications must usually be bought for any regulated details.

 

[bcd]

How long do you expect it to last? Is replacing a valve every few months ok?

 

[gerhardl]

Depending on application, not submerged might be ok, but operation time of the existing before change now indicates if you need better materials. Always detailed information is missing to give the best answer! What is wrong with the one to be changed?

 

[helpyou]

Hi bcd & gerhardl,

The existing ones failed (some from actuator, some from valve, passing etc). The valves are 20 years old and plus. I expect the new ones to last at least 10 years, the longest period possible. The valves are not submerged. The material for the existing ones as per the datasheet is :

Body & disk : ALBC
STEM: Monel
Seat: BUNA-n

Pressure max 10bar
Temp : 0-60 C

Is there a reference to base my selection of material to?

Thank you

 

[gerhardl]

I believe ALBC stands for aluminiumbronze, in which case the old material is far superior to the ones you propose, regarding general resistance against seawater.

The problem is that earlier bronze valves have (almost) vanished from production and if commercial offered are very high prized.

In stead of specifying materials I think you would be best served by starting an 'open end inquiry'. Ask renowned suppliers for preliminary offers, based on all operational and application details, and for two proposals: the suppliers cheapest and the suppliers safest/most recommended solution.

Start your evaluation from this, supported by input from the competing and up-to date market, instead of selecting the solution on a pure material basis.

Actuators should be included and delivered mounted/supplied/adjusted.