×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

12% HypoChlorite in PVC Pressure Main

12% HypoChlorite in PVC Pressure Main

12% HypoChlorite in PVC Pressure Main

(OP)
We have had several crack like failures in a pvc forcemain that experiences surge pressures of 140 psi.  We dose this line with 12% Sodium Hypochlorite.  I read a disclaimer on a plastics chemical resistance chart that said that the properties index values were only true under gravity conditions.  It said that under pressure conditions some chemicals that are normally unreactive can make plastics more brittle.  Are we increasing the brittlness of the forcemain by dosing with the hypochlorite?

Thank you.

RE: 12% HypoChlorite in PVC Pressure Main

Typical choice for low-pressure piping is PVC Schedule 80 socket welded pipe and fittings. Do not use threaded joints for sodium hypochlorite connections if possible. Over time, a threaded joint will have a tendency to leak and threading the pipe reduces it structural integrity. PVC piping should not be used for high pressure, typically over 50 to 60 pounds since failures result in potential injury. If higher pressures are used with PVC, use soft start motors on pumps and slow opening and closing valves if automated valves are used to start and stop flows. Velocities in PVC sodium hypochlorite piping systems should not exceed 7 feet/second and better results will be achieved if the velocities are kept less than 5 feet/second. Care must be taken to use an industrial grade cleaner and glue for the PVC and to follow the manufacturer’s installation instructions. PVC installed outside must have UV protection.

Copied from this guide:
http://www.omegachem.com.au/docs/mega_handbook.pdf#search=%22sodium%20hypochlorite%

http://www.powellfab.com/technical_information/documents.asp

Also see thread367-127764

http://www.eng-tips.com/viewthread.cfm?qid=127764&page=8

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources