BEST way to join PVC & Cast Iron for service in ground

[newbplumber]

I recently tunneled under my house to repair a broken PVC sewer line from the toilet. While I was down there I noticed other joints leaking. All the leaking joints are connections between PVC & cast iron. A rubber sleeve is slipped over both and about 4-6 hose clamps are used on each joint.

This work was performed by a professional organization 7 years ago. It is not under warranty. Given that I do not plan on tunneling my sewage lines in the next 30+ years, what is the best possible way to joint PVC & Cast Iron. All joints are vertical ranging in size from 2" to 4". I'm thinking the best possible joint is to glue the PVC directly to the cast iron using marine grade epoxy (West Systems). What are your thoughts on this approach? And thanks in advance!

 

[Jadnashua]

Those are code compliant for use underground, but like anything, they must be installed properly. That includes actually torqueing them down properly and backfilling things to keep them in alignment so they don't become stressed or torn. Also, the outside of the CI must be smooth and clean for the thing to make a proper seal. While the ID of the pipe is standardized, there is a slight variation in the OD, so if the fitting was designed for a pipe slightly larger, or it wasn't torqued properly, or if the pipe had raised lettering on it that wasn't ground down level, the fitting may not seal well long term.

Vertical layout is tougher, and an offset might be harder to prevent. I'd consider using a no-hub clamp verses the one that is just a rubber sleeve...the no-hub has a SS reinforcement sleeve around it to help keep the pipe ends aligned. You'd want to double-check their certification for use underground to be sure. I would not use any epoxy trying to make this work.

 

[Sponsor]

 

[MACPLUMB]

Per most plumbing codes stainless steel type bands are required for installation, for the reasons you posted

 

[newbplumber]

Per most plumbing codes stainless steel type bands are required for installation, for the reasons you posted

When you guys say per code, does code mean "best and most durable" or does code mean "viable due to economic nature of solution." Because given the quote for tunneling my sewage lines (& basic PVC repair) was $5 grand, I'm thinking code isn't up to snuff. Codes are written to offer viable economical (practical) solutions. But I'm not sure the code takes into account $5 grand tunneling every 7 years. Does high grade epoxy go above and beyond code standards?

 

[newbplumber]

Those are code compliant for use underground, but like anything, they must be installed properly. That includes actually torqueing them down properly and backfilling things to keep them in alignment so they don't become stressed or torn. Also, the outside of the CI must be smooth and clean for the thing to make a proper seal. While the ID of the pipe is standardized, there is a slight variation in the OD, so if the fitting was designed for a pipe slightly larger, or it wasn't torqued properly, or if the pipe had raised lettering on it that wasn't ground down level, the fitting may not seal well long term.

Vertical layout is tougher, and an offset might be harder to prevent. I'd consider using a no-hub clamp verses the one that is just a rubber sleeve...the no-hub has a SS reinforcement sleeve around it to help keep the pipe ends aligned. You'd want to double-check their certification for use underground to be sure. I would not use any epoxy trying to make this work.

Why is epoxy bad in this situation. Forgive me for not defaulting to the code, but it's been 7 years and all indications are that this was properly installed. I'm thinking anything involving a rubber sleeve (SS reinforced or not) tensioned with hose clamps has a life span shorter than 10 years. Epoxy made to handle situations much tougher than this application may be a bit of over engineering. But were not talking about an under cabinet fixture here. This is a $5 grand tunneling job every 7 years I'm looking at.

 

[Terry]

There are several sizes of pipes, and couplings for every instance.
There is 1920's cast which adds 1/8" to the pipe size, 60's and newer that adds 3/8" and plastic which adds 9/16".
The right two sided coupling makes those transitions.

 

[Dj2]

Why is epoxy bad in this situation. Forgive me for not defaulting to the code, but it's been 7 years and all indications are that this was properly installed. I'm thinking anything involving a rubber sleeve (SS reinforced or not) tensioned with hose clamps has a life span shorter than 10 years. Epoxy made to handle situations much tougher than this application may be a bit of over engineering. But were not talking about an under cabinet fixture here. This is a $5 grand tunneling job every 7 years I'm looking at.

A correctly done main sewer replacement job should last more than 7 years.
About the cost: you should always get more bids, keeping in mind that a higher bid doesn't necessarily mean better quality. Scrutinize/qualify the installer before you hire him. When and if I hire tradesmen, I look for experience, reputation, word of mouth, trustworthiness BEFORE looking at the price.

 

[newbplumber]

I still have an itch to use epoxy but all of your responses have steered me towards a rubber coupling. Basically something in the installation process went wrong. Either used incorrect couplings or installed them incorrectly. I'm a bit disappointed as the company who did this is highly regarded.

 

[newbplumber]

There are several sizes of pipes, and couplings for every instance.
There is 1920's cast which adds 1/8" to the pipe size, 60's and newer that adds 3/8" and plastic which adds 9/16".
The right two sided coupling makes those transitions.

Thanks for your response Terry! What is the estimated life span of the coupling if the proper coupling is used and installed correctly?