Cast Iron Tie-In

[Mechville]

We have an old 8" cast iron gas main system that we are replacing with PE piping, and the plan is to tee off from the existing cast iron pipe and then run HDPE parallel to the existing cast iron line. What's the best way to tee off of cast iron pipe? I typically work with steel piping where we tee off by welding on a bottom out fitting and hot tap through the existing pipe wall.

I know you can use couplings to switch from cast iron to PE pipe, but that's inline and not a tee. If I can purge the existing line, I suppose the easiest thing would be to remove a section of the cast iron pipe, replace it with a coupling to PE and then a PE elbow to our new PE line, and cap the other side of the to-be-abandoned cast iron piping. But if purging isn't an option due to line downtime and lack of valves, what are alternative options?

Thanks,

 

[TugboatEng]

You'll likely need to cut a section out of the pipe to make room to insert the coupling. Fabricate your T with materials that make the transition possible with off the shelf parts. Make the legs of the T long enough to slide a stopless compression coupling completely on each side of the T and cut your existing pipe section wide enough to clear the entire assembly. Couplings such as Aeroquip Flexmaster are available with biting rings for axial strengthen and require no special tools to install.

 

[LittleInch]

True cast iron as opposed to ductile Iron is quite brittle and welding is very difficult.

But cold taps are posisble. This reckons to be a cast iron main

https://www.youtube.com/watch?v=PxLxvR1bk68

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[HTURKAK]

[quote

.... What's the best way to tee off of cast iron pipe?

I know you can use couplings to switch from cast iron to PE pipe, but that's inline and not a tee. If I can purge the existing line, I suppose the easiest thing would be to remove a section of the cast iron pipe, replace it with a coupling to PE and then a PE elbow to our new PE line, and cap the other side of the to-be-abandoned cast iron piping. But if purging isn't an option due to line downtime and lack of valves, what are alternative options?

Thanks,][/quote]

The best way ( at least for me ),
- Purge the CI line.
- Cut the CI pipe and install an adaptor sleeve ( CI to PE )
- Install PE bends to both lines
- Abandone the useless portion of the CI pipe

Good Luck ..

 

[Mechville]

Thanks everyone, I think that's the way to go!