View Full Version : what type of pipe do i have

12-10-2008, 05:40 AM
hello, replacing part of a vent and drainage pipes connected to it.how can i tell if the pipe is cast iron or galvanized.it is a 1950 s home.tried cutting the vent pipe with a blade that is meant for cast iron.wont cut it.used a metal blade and it did cut it.the pipe looks like steel but it is not grey.drainage pipe is the same material but it is hub and spigot connections.can a system have both types of pipes connected to each other.thanks jvl

12-10-2008, 05:53 AM
Galvanized/steel pipes are silver colored. Mixing steel and cast iron was the normal way to install the piping in the "old" days. The larger sizes were cast iron and the 2" lines were either steel or cast iron depending on the complexity of the system and 1 1/2" were usually steel.

12-10-2008, 05:54 AM
What size pipe is it???

Generally galv. pipe was used on 2" and smaller pipe while 3+4" was ci. both should be about the same OD.

12-10-2008, 08:13 AM
the pipe size is 2"

Gary Swart
12-10-2008, 01:07 PM
Galvanized steel joints are made by threading the pipe and screwing it into fittings. Cast iron is joined with molten lead and Oakum which requires a fairly obvious flared hub. It should be very obvious by looking at the joints what kind of pipe you have. If you still can't tell, you may be into something beyond you abilities and really should bring in a professional.

12-10-2008, 01:27 PM
Most likely you have cast iron. I am redoing my DWV system where the old had cast iron and steel combination. Lenox makes a decent sawzall carbide blade (around $20 for two) that works well and they also make a diamond blade ($23 ea )that works even better, it is very time comsuming. Keep your blade cool with water helps it cut faster and last longer. Good Luck.

12-10-2008, 03:56 PM
If you have room to wrap around a snap cutter, it's MUCH faster. Could be risky if the pipes are really old, since they sometimes don't snap cleanly and crush instead, but if they do, it may not be the best idea to leave them in anyways. Does NOT work on galvanized.


12-10-2008, 04:01 PM
just finished the job replaced vent piping,wye combo,sanitary tee,30 feet of 2"' drain pipe,plus fixture drain.that 2" pipe is diffently gal/steel that runs into hub and spigot that it appears to be caulked/glued. there seems not be lead or oakum joint.could a galvanized/steel hub/spigot ever been made or could a galvanized /steel drain pipe fit into a cast iron hub/spigot?going to see a engineer/contractor saturday to show him what i have.thanks gary

12-10-2008, 05:56 PM
A plumber may be less $$$ than an engineer...then again ...:)

12-10-2008, 06:54 PM
very close friend,no charge,he has been a building inspector for 13 years,a contractor for 10 years,a teacher for 14 years,engineer for ?i am going to break apart the fittings.remember this is the work of a plumber who didnt understand the 1/4" per foot drop for piping.

12-10-2008, 08:02 PM
In my house i replaced 3 main stacks, 2 of which were 4" galvanized, the other was cast iron. The fittings, and couplings were HUGE 4" threaded.
I had to cut those pipes, what i learned here was slow speed on the sawzall, lots of blades, and someone spraying spray lube on the blade while cutting....that last one was the magic.

I guess the 4" galvanized was not common, but my local old school plumbing house owner was familiar with it, can't remember what he called it, but he had a name for that type of DWV system.

12-11-2008, 12:52 AM
remember this is the work of a plumber who didnt understand the 1/4" per foot drop for piping.

Or a house that settled..I have seen that...

12-11-2008, 05:15 AM
rmelo99,thanks for the info.i am going to cut the fittings off the gal pipe to see if it is threaded or not.the settling of the house could be but the fixture drain was pitched back towards the trap and not towards the san.tee and the drain pipe right below it was pitched 3/8" per foot toward the main drain running along the same run.thanks

12-11-2008, 05:25 AM
A diamond blade in an angle grinder cuts very fast!

12-11-2008, 05:37 AM
diamond blade cuts thru gal.steel?

12-11-2008, 05:50 AM
Diamond is not ideal for cutting ferrous metal. Carbon (diamond) will disolve in molten iron so the diamond abrasive will erode much more quickly than when cutting stone or whatnot. Personally I would use a cutoff wheel in a grinder. They're also cheap -- like me.

12-11-2008, 06:47 AM
For Cast Iron! For galv. use a Lennox gold blade! The Lennox Gold will also cut cast iron but not as fast as the diamond in the angle grinder.

12-11-2008, 04:09 PM
from the roof down to floor level ,the vent pipe is 2" galvanized.it then enters into a cast iron sanitary tee.also entering is a 1 1/2" copper fixture drain pipe that is threaded into the cast iron 2x2x11/2.coming out of sanitary is a short piece of galvanized that is connected to combo wye made of cast iron.horizontal clean out section is a combo cast iron and galvinized.existing from the other side of wye is a cast iron pipe 2"that enters into a galvinized hub that has a galvinized piping that enters into a santary tee made of cast iron.anybody ever seen this setup.how do i know because i dissected each piece that i removed and replaced.

12-13-2008, 07:22 AM
I have a diamond wheel that I have been using for months cutting steel and cast iron pipe, chains, and almost everything ferrous, but no tile. I have no idea what kind of connection you are referring to because your description is all over the place with little real detail. A picture would help. cast iron and steel were interchangeable and connections between the two were common.