Chemical sewer material selection

[morganjp]

I am having trouble selecting a material for a replacement chemical sewer. At some locations boiler blowdown and steam condensate are discharged, so temperatures can run to 212 F. The combined effluent (blowdown, steam condensate, and process effluent) has a pH of 11.0 - 11.5 (primarily the result of the process effluent). The stream is primarily water with traces of methanol, ammonia, and amines. Much of the water is from the reaction, so it has no hardness (neither does the steam condensate).

System is a gravity sewer and sizes range to 18-inch.

 

[metengr]

Try cast iron piping with couplings.

 

[morganjp]

Will I have a high corrosion rate with the elevated temperatures and high pH? Ductile iron pipe was also suggested. How would this compare to cast iron?

 

[metengr]

The stated temperature of 212 deg F is not that high for this piping material. Also, when I worked in a metallurgical lab with chemical etchants, the sewer drains were either cast or nodular iron - never had a corrosion problem.

 

[unclesyd]

In our power house we have Durion Pipe, high silicon iron, in areas like the drains from the water lab, drains from the feed water chemical injection mixing and pumps, drains form the ion exchange area. These trunk lines then go into a vitrified clay collection pipe to the waster water sump for the power house.

http://foundry.flowserve.com/pages/pipeFittings.asp

 

[arunmrao]

High silicon irons though suitable pose a problem in handling. They are extremely brittle and prone to cracking if not handled carefully. Grey or Ductile irons can be used instead.

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