splicing in a new drain

[jasonb]

Lookin for my best opion to splice in a drain into an existing pipe. This is in a commercial building in a ceiling space. I will be putting in a sink in, on the floor above. the pipe i will need to tap into is 3" galvanized. Is it best to cut out a section and spice in or do they make a saddle fitting or sorts i could use. remember i will be working above a ceiling in a space that is about 3' high. Any advice on what my best option is.

[Randyj]

I'd really like to see some more replies to this one... I haven't run into any 3" galvanized used for drains or sewers. If it were me I'd use some kind of mechanical coupling such as compression coupling or no hub couplings on each side of the tee which would be fitted with nipples (no threads on the splice end. I'm sure that saddle couplings or tees are available and I'm sure they're not cheap.

[Terry]

I haven't seen 3" galvanized used for waste either.
I've seen galvanized that large used for roof drains and for fire protection before.

I wouldn't use that line until I determined that it was what it was.
It could even be a water supply line.
Wow! Now that would be a mess cutting into a line under pressure.

[Gencon]

If its a drain, its likely cast iron. In which case the best way to tie in another drain is to cut the pipe and add a wye.Use a soil pipe or snap cutter to cut the pipe and use MJ couplings for the connections.

You may have to do the same for the vent, or else its copper.