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duffers 11-08-2007 01:19 PM

Cast iron vs galvanized steel.
My inspector told me that i have both Cast iron and galvanized steel waste pipes. How can i tell the difference between them? I know from a practicality standpoint cast iron is good and galvanized steel is bad. So i want to try and find out what pipes i need to remove.

What is the best way to describe /tell if it is galvanized stel pipes? They are probably 40 yrs old.


justdon 11-08-2007 01:48 PM

Cast iron pipes usually come in 3-4-5' sections with a big bell end on one end and are leaded together where they join. Galvanized pipes are brighter grey (more) shiny looking smooth pipe with 'threaded' ends into a cast or iron elbow or tee, BUT generally threads still show a little. Cast iron is very thick and heavy. Galvanized not nearly as heavy. Galvanized is 'usually' used for sink drain,,,like 2" or 1 1/2",,,cast is 2-4 " diameter and usually used in that era of homes for the stack all the way to the roof. BOTH can be troublesome and rust thru. IF cast stack is bad you have to replace anything on top of problem area,,,best with newer PVC plastic. easier and better to work with!! Like a chimney IF you start from the bottom you may end up with whole thing on your head!! MAY require walls to be opened up for access. Whenever I would reroof with a cast stack I at LEAST replace the top thru the roof portion!!(flashing and sealing reasons.) It is all GOOD as long as it works, drains, and doesnt leak!!! Find another place to spend your money instead,,,until the time comes OR you have walls and access open anyway!!! Cast to plactic hubs are available,,,as it no hubs and rubber hose clamp connetions to connect galvanized to Plastic. Galvanized water supply pipes are also common to this era of houses!!! IF it is soft lead(either inside or supply line into house!!!),needs to be replaced for health reasons!!

duffers 11-08-2007 02:36 PM

Thanks.. My supply pipes are copper so that's good.. I was trying to figure out which pipes were galvanized so i'd know which to replace. Trying to replace it before it starts leaking. However, according to what you wrote it probably makes sense to replace them both?

Marlin 11-08-2007 03:49 PM

Why are you changing them?
If you're doing a re-model and are going to have all the walls out I would defiantly re-pipe everything. If you're just changing pipes to change pipes I wouldn't even bother. When something starts leaking fix it then. I wouldn't bother changing the cast either, especially on the stack.

duffers 11-09-2007 10:22 AM

I was thinking of changing them to avoid having a leak and then having to repair that damage.. They are 48 years old.

47_47 11-09-2007 10:50 AM

When you change them, I would wrap them with insulation. PVC is noisier than cast or galvanized.

majakdragon 11-09-2007 11:09 AM

You can tap on the pipes with a metal screwdriver. Cast iron will give a "thud" sound as it is thick material. Galvaized is more of a "pinging" sound. If you get into replacing the piping, you will find cast iron for the mains and threaded galanized piping connecting to it.

scorrpio 11-09-2007 02:28 PM

My house is about 65 years old. I got about the full spectrum of waste pipes: PVC, copper, lead, etc etc. But main stacks (two of them) are cast iron, and show no sign of problems.

My neighbor's house is 85 years old, and his cast iron stacks are among the few things that survive from original construction. So, your cast iron still got quite a bit of time to go. But galvanized.... I'd worry. I hear its lifespan is around 40 years. MY house does not have a bit of galvanized (as far as I could determine).

justdon 11-11-2007 02:25 PM

I have seen cast leak
I have seen cast iron stacks leak,,,but I have seen 100-year old stacks NOT leak either. Problem with cast IS as a horizontal drain pipe it settles shut with crap like they all do. Cast is 'rough' on the inside so it tends to clog faster.

Now dont get me wrong,,,I dont say replace JUST to have something to do,,,,BUT ,,,,I have seen where they charged MORE to clean a drain than somebody could have cut it ALL off and replaced THAT part ... Most anybody can cut and glue!!! Like a laundry sink horizontal drain,,,soap scums it up terrible. Snake it out till it drains too hard and whack her off and switch to plastic with a good slope,works MUCH better!!

joed 11-11-2007 06:16 PM

I believe there are some regions that still require the use of cast. Check you local codes before you replace it with PVC or ABS.

lonsplumbing 08-04-2009 10:35 PM

If it is not broke dont fix it .

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