Pump in Cast iron, fluid with Cl

[EngMecBra]

Hi everybody!

Here I have a centrifugal pump bought but not manufactured yet in cast iron, and this pump shall handle water with Cl content round 500 ppm.

The client has said that we MUST change material from cast iron to SS 316.

Will I have problems with corrosion and the client is correct or may we buy pump in cast iron?

Please let me know if you need any additional information to help me.

Tks!

 

[Ripz]

You'll get high general corrosion on the CS and pitting corrosion and possible Stress Corrosion Cracking on the 316 SS.

 

[EdStainless]

If the water is cold then cast iron would be the most common choice. There will be corrosion, but the pump will last for a long time if it runs continuously. If it is allowed to sit wet but not flowing then it will not last long at all.
A 316 pump will not like sitting stagnant either. CSCC is unusual in pumps because the cast parts are lightly stressed and the temperatures are low.
Can you get a pump in NiResist, Ni cast iron? This is a common material for this service.

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Plymouth Tube

 

[EngMecBra]

Ripz,
What is the solution? Which material should I use?

EdStainless,
Fluid temperature is 34 Celsius degree. Is it too high considering this "corrosion condition"? And what is "CSCC"?

Tks!

 

[Ripz]

ClSCC is Chloride Induced Stress Corrosion Cracking.

At the temperature you operate at, it should be an issue, as ClSCC usually occurs above 60C.

316 SS would be suitable, but may have some localised pitting. Cast Iron can work once you have a proper internal coating.

See link below for more info.

Link

 

[SJones]

http://www.nickelinstitute.org/Tech...neWaterDesalinationandOilfieldBrinePumps.aspx

Isn't the client always right (until they want a cast iron guarantee - pun intended)?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.