In service repair of aeration piping

[trashcanman]

I have a project to specify repair of large (48-60" dia.) steel aeration piping with a lot of pinhole leaks. This is for a sewage treatment plant. The system cannot be opened for internal repair. Air pressure = 8 psig, ambient temperature. The system can be shut down for 1-3 hrs. I am trying to put together recommendations for the repair. I think some type of fiberglass/resin wrap would work. Anybody out there with suggestions?

 

[dicksewerrat]

Is it underwater? Can you get to the entire circumference? If under water , can the water be drained? Why does it have these pinholes? Internal or external corrosion? I don't think there is a 'wrap' that can stand alone as a new pipe.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Pulpeng]

I would suggest looking at trenchless rehab methods. Look up "Cured In Place Piping". The best known one is Insituform but there are many others. It can all be done from the top side.

 

[dicksewerrat]

Three hours is not long enough to do CIPP rehab. what are the parameters of this line, dia., length. depth of water over the line, access points, . If 3 hours is the longest this line can be depressurised, You may have to send a diver in with a can of epoxy sealant. The water will show them where to apply it. This may sound a little silly and not making your problem important, but your constraints and our lack of info on this make it difficult to give decent advise.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[bimr]

You say it is steel. Why don't you just weld a new section of steel over over the old one?

 

[stanier]

Your aeration piping is eventually going to fail completely. I would suggest you start planning a new system and plan to cut over in the 3 hours you may have. Perhaps you can tie in some sections of the biological reactor progressively.

Spiral wound stainless steel 316L is used in Australia for such piping.

If you wrap it with FRP eventually the corroded steel is going to end up in ou reactor diffusers and then you will need to replace them too.

 

[rcooper]

Depending on the size of the diffuser assembly, you could look at making a new free standing assembly with lifting equipment, connected to the blower via a flexible detachable hose so the whole assembly can be removed for future maintenance without draining the aeration lane.

 

[Pulpeng]

Agreed - CIPP is probably not feasible with the time limit but others like Fold and form would work as far as relining it - or a new line and grout the annular space etc with a fast cure There are many different trenchless methods that can rapidly use the host pipe for support and rehabilitate it - depends on access etc.

 

[dicksewerrat]

Where is the 'more info'?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com