Oily water sewer piping material 1

[mohshalzad]

I am preparing a piping spec for a condensate treatment facilty. We have a UG oily water sewer which will be atmospheric and the temprature would raise up to 580F. The required service life is 20 years.
Can anyone help me with material selection? The given options are carbon steel, ductile cast iron, fiberglass and reinforced concrete, I am not sure whichone will be the best option.
Thanks in advance.

 

[bimr]

FRP is a good option at those conditions.

 

[mohshalzad]

Thank you bimr,

Correct me if I am wrong but but FRPs are not suitable for 580F, are not beenig recommended for temperatures more than 150-200F.

 

[rconner]

I would think the form of water at 580 degrees F. and "atmospheric" pressure would be steam, as opposed to liquid water. As this temperature is also beyond any common gasket material limits for even ductile iron pipe, and perhaps also all linings with the possible exception of glasslining, you may be pretty much left with specialty (welded?) steel for this application.

 

[mohshalzad]

Thanks rconner, you are right 580F is occasional, for times when we have to drain hot oil drips.
Based on your comment, can I assume for such temperature there will be no option but welded carbon steel piping? Even ductile iron will be out of options?
Thanks again.

 

[bimr]

Sorry, I overlooked the temperature. Some types of FRP piping will work well with condensate but as you note there is a maximum temperature limit.

Steel pipe will probably not survive for 20 years in this application. Condensate is corrosive. The pipe will also be attacked by the soils.

Some of stainless steel alloys will stand up to the fluid but will also be susceptible to exterior corrosion.

If the high temperature occurs only occasionally, the FRP may work. You might want to run the question by the supplier. The performance limits on the pipe are based on the combined affect of temperature and pressure, not just temperature.

You may also consider revising your process to eliminate the high temperature.

 

[mohshalzad]

Thank you Bimr, thats a good point, I should talk with our process to see how we can reduce the risk of having temperature raise.

 

[agua84]

What is the volume of hot oil drips vs volume of (I assume) cooler temperature water? If there is enough cool water volume, perhaps a sump with a baffle or similar to cool the hot oil in before it flows to the pipe(s)?

 

[mohshalzad]

Yes, actually there will be a liquid trap which helps to cool down the fluid. We are thinking about adding a valve after liquid trap as well.

 

[rconner]

I suspect you already know this, but from the standpoint of safety (for any reading this now thread now and in the future, including at least those who have not spent a good bit of time in the kitchen!) I'm going to go ahead and mention that under some circumstances particularly hot oil (or for that matter anything else molten with very high heat potential) poured on top of water can be a very deadly combination. This is mentioned to some extent at the site

http://books.google.com/books?id=yZ...age&q=hot oil hitting water explosion&f=false

, at least in the context of tanks etc as , "If water is trapped in a confined space and then heated to a temperature well above its boiling point, a violent physical explosion may occur." [I might only change the word "may" to "will", at least if the confinement is not fully effective or fully-protecting e.g. of bystanders!]

While the converse of this, i.e. water poured or sprayed onto hot oil, may not be quite as bad as I believe demonstrated by the "Mythbusters" at

http://www.discovery.com/tv-shows/mythbusters/videos/water-and-oil.htm

, both certainly fall into the don't try this at home category, and I can't believe the Myth guys didn't vociferously mention the very much inadvisability of anyone trying the demo the other way around!

 

[BigInch]

rconner, thanks for adding a sanity check to this topic, except for the Mythbusters bit of course.

you must get smarter than the software you're using.

 

[bimr]

A Boil Over is generally caused by dormant liquid in a tank. It is not something that you would see from a flowing sewer.

http://www.williamsfire.com/Libraries/CODE_Red/Boilover_Sleeping_Giant.pdf