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

Related Articles


In-Situ Large Diameter RAS Pipe Repair?

In-Situ Large Diameter RAS Pipe Repair?

In-Situ Large Diameter RAS Pipe Repair?

I'm looking to repair some large diameter (42", 30" and 20") steel RAS pipes. It needs to be a medium term solution, as we can't keep up with "patchwork" and they are scheduled to be replaced in just under 10 years. Weaknesses are at the welds and throughout the pipe wall.

Ideally, I'd like something external, so I don't have to take these out of service. As far as I can tell, internal cast-in-place solutions aren't really suitable for such diameters anyhow. I'm seeing the Henkel's Loctite Composite Repair System pop up a lot, but I don't see any case studies relevant to my type of service.

Does anyone have any experience with such repairs? Could you please share the method you used and how satisfied you were with the outcome?

RE: In-Situ Large Diameter RAS Pipe Repair?

This type of patching will work in the short term, maybe for several months and then the patch will break away or start leaking as the corrosion continues.

The preferred patch is to weld steel to the exterior of the pipe.

RE: In-Situ Large Diameter RAS Pipe Repair?

First of all, what is RAS pipe? Is it under internal pressure? how much? Can segments be taken out of service for a day at a time? What about Quakewrap?

Richard A. Cornelius, P.E.

RE: In-Situ Large Diameter RAS Pipe Repair?

Thank you both for your replies.

RAS = Return Activated Sludge, it's the "bottom" of the final clarifiers that is being returned to the aeration tanks to help maintain the microbial populations. I am not exactly sure of the pressure, but I don't think it would exceed 200 kPa. It would be preferred to not take it out of service, but of course, if it breaks it will be out of service anyhow!

I will look into the Quakewrap. I'm not sure the idea of welding would be well received as I believe some of that area is Class I Div I.

Right now the supervisor is preferring patchwork, but I would like to see if I can offer him some better ideas.

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!


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