Caustic piping

[pwees]

I have read somewhere that it is poor practice to use small diameter piping for caustic. Any truth to this?
Pwees

 

[dprice]

If your flow rates are small, I am not familiar with such a design practice. Typical minimum size industrially is 2" or 3" for the heat loss reasons. You must be careful about freezing the liquid, and pumping losses. These can be handled through appropriate tracing etc.

Regards,

dprice

 

[Isimbard]

The small diameters can lead to problems if and when the caustic settles out or for what ever reason and comes out of solution.

This may lead to pipe blockage.

Better to design the system to keep the fluid in constant motion irrespective of flow path around elbows and other restrictions.

 

[MJCronin]

pwees,

I suggest that you not rely on any anecdotal information from an engineering-tip bulletin board. I suggest that you contact the caustic soda vendor for his MSDS and Handling Guidelines ( I also assume that you are talking about 50% caustic... the concentration that is typically stored for water treatment usage...) Contact both PPG (

http://www.ppg.com)

and Dow chemical for thier guidelines.

Try

http://www.dow.co.za/causticsoda/handl.htm

Good Luck !!!

MJC

 

[waynef]

I don't know about caustic but I do know that for sulfuric acid, high fluid velocities will degrade the protective oxide coatings that form in pipes leading to increased corrosion.

 

[ralphsare]

The problem associated using a small bore pipe for caustic service is the welding. if the joints are socket, then u may have a rpoblem related to creavice corrosion. of course u can also do a butt weld but it becomes more of a prblem for size under 1".
The other thing to remember is PWHT depending on the concentration of the caustic and the temperature.

 

[MJCronin]

I think we are all guessing here because the question is vague....

Is the original question "Will my caustic freeze up with small diameter pipe and if so what is the smallest size recommended ?"

Or is the question "What type of pipe joints are acceptable ?"

Additionally, are we talking about 50% caustic here ?

Or is PWEES just asking questions.....for the hell of it ??? Hmmmmmm........MJC