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!

*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.

Jobs

Isolation Flange Kits for Propane/Butane Buried Tanks

Isolation Flange Kits for Propane/Butane Buried Tanks

(OP)
Hello folks,

Recent Cathodic Protection survey of buried propane and butane tanks indicated that they are underprotection.
After investigation, the CP technicians think that low protection is due to huge current leakage much higher than the design calculation. They recommended to install isolation flange kits to all external pipes connected to the tanks which will prevent leakage and improve CP protection level of the tanks.
I would like to ask you experts in CP, is it acceptable to install the isolating flange kit or not as the fluid inside the tanks is explosive and I found in some NACE books that:
Under no circumstances should an isolating device be installed where an explosive or combustible environment is present.
‚Äč
Your advice and explanation of the subject is highly appreciated.

Cheers.

RE: Isolation Flange Kits for Propane/Butane Buried Tanks

I believe that the warning has to do with the possibility of a potential difference and hence a risk of spark across the isolation. Think a lightning strike.
I have seen isolation kits that have a kit to tie the two sides together electrically, but with some circuitry to limit the current draw. These are usually a combination of diodes and MOVs.
Do some more research.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Isolation Flange Kits for Propane/Butane Buried Tanks

Where an explosive or combustible environment is present.... which in your case is only possible if you loose containment / have a leak in the tank. Isolating kits are used on HVP pipelines all the time. Yes, think spark across the isolation, igniting vapor, like if you were in a closed environment.

RE: Isolation Flange Kits for Propane/Butane Buried Tanks

As a side note, if arc prevention happens to be required to cover the occurrence of minor flange leaks or due to an ignitable atmosphere from other sources, I believe there are methods to isolate cathodic protection while preventing arcing. Look into SSDs or solid-state decouplers for more info but I think it may solve your CP issue without introducing a fire hazard. If you have any questions I may have a bit more feedback.

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close