Digester Tank Wall Casting with Caulked Lead Joints

[Kodiak31]

I'm working on a WWTP's anaerobic digesters originally constructed in the 1960's. The digester tanks have cast iron (CI) pipe with several CI bell end wall castings penetrating the tank walls (photo attached). The bell end/CI plain end joints are made up with oakum/jute and caulked lead (photos attached). Maximum pressure acting on the joint is about 30-ft of H2O. There is evidence of leakage staining emanating from many of the joints.

Our project will replace the CI pipe with new ductile iron. I prefer to maintain the CI wall castings if possible. The concrete around the wall castings is in good condition and cutting the castings from the tank wall may do more harm than good, create leakage points, etc.

Is there a more modern joint or sealing method than could be retrofit to the CI bell / plain end ductile connection in lieu of another leaded joint? Any products or techniques to retrofit a mechanical joint type connection here? Has anyone run into this before?

 

[JedClampett]

If the pipes are smaller than the sleeves, you can seal them with link seal. But you'll need a gap. There's a link seal calculator that can define the required gap.

 

[HTURKAK]

I will suggest two alternatives depending on the annular space btw. CI bell end and DI new pipe ;

- The use of Ringraum-Dichtung ( ring seal )

https://psi-products.de/fileadmin/user_upload/Produktkatalog/Dichtungstechnik_KATALOG_PSI.pdf

- Use wall flange ( welded to DI spigot pipe and fixed to the RC wall with expansion bolts ) fill the annular space with joint filler and provide rubber gasket btw flange and CI socket surface.











Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[bimr]

We cored the concrete and used link seals for sealing.

Be aware that you have to use ceramapure piping instead of ductile iron pipe:

"Digester Gas – Not!
Ductile Iron pipe and fittings are not suitable for digester gas service; thus, U.S. Pipe will not knowingly supply products for such a project. At one time, the ANSI A21.52 and A21.14 standards governed the manufacture of Ductile Iron pipe and fittings (respectively) for gas service. These standards were withdrawn a number of years ago. Ductile Iron pipe for gas service was required to undergo special processing and testing. The equipment needed is no longer available at any U.S. Pipe facilities."

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