We are fully aware that quite a number of people around the country will wonder what the heck we are talking about but we thought it was time to talk about cast iron pipe and cast iron fittings. Cast iron pipe and fittings are used in many areas around the country but it’s a fine material and if nothing else this may be a history lesson some day.
Two Kinds of Cast Iron Soil Pipe and Fittings to Choose From
Just to clarify there are two different kinds of cast iron pipe and fittings, hub (bell) and spigot and no-hub soil pipe. No hub soil pipe is much more common than hub and spigot soil pipe. Hub and spigot soil pipe joints are either caulked joints or made with neoprene rubber that are compressed as the pipe enters the hub sealing the joint. No-Hub soil pipe is joined using stainless steel no-hub couplings and gaskets.
Caulked Soil Pipe Joint
When we describe how these joints are made there are some that will think we are talking about pipe used in the early 1900s however just so you know this type of joining method is still used extensively in Chicago even today.
A caulked joint is made with molten lead (We didn’t invent the joining method. It’s nuts) and oakum caulked with caulking irons to make the joint water tight. (Please take a look at the tools listed below.) Lead is available in 5lb ingot and 25lb bars. (Please see a picture of the different types of Oakum and a strand of lead.)
There are two types of oakum used to make plumbing joints.
Is hemp fibers that have been soaked in petroleum based pitch to make it water resistant and to protect it from waste water.
Some definitions say it is untarred Is hemp fibers but that is only partially true. It is untarred but the fibers are treated with bentonite. Which is a type of drilling mud that swells considerably when exposed to water. It comes slightly damp or moist and when it completely dries out it’s pretty useless. So when the white oakum is exposed to water is expands inside the joint making it water tight. White oakum is the preferred oakum used for hub and spigot cast iron.
The lead is heated on a plumber’s lead furnace (See picture of plumber’s pot and furnace) and poured into the joint with a ladle. Lead should be heated until it is hot enough so that it does not stick to the ladle, but it should never be overheated. Over heating lead will burn it into slag. You will know that the lead is hot enough when the lead no longer sticks to the ladle.
****HOT TIP (Pardon our feeble attempt at humor but it is hot) Be very careful when adding new lead into a pot with molten lead. Lead that has any amount of moisture or that is frozen WILL explode when added to a molten lead pot. Preheat the lead and or cold ladle to evaporate any latent moisture.
Here are the steps to cut and assemble hub and spigot pipe and fittings with yarned and poured joints.
How Much Lead and Oakum Do I Use?
12oz of virgin lead per inch of diameter of pipe, so 4” diameter soil pipe would require 4lbs of lead. As far as oakum is concerned you use 2”oz for every inch of diameter so for 4” diameter pipe you would use 8oz of oakum.
If you are afraid of moisture in a hub being poured add a couple drops of oil to the oakum. Just a few drops will displace the moisture and allow for a safe pour.
***HOT TIP*** I know there will be old school master plumbers commenting on how you need the right tool for the right job but both the inside and outside of the joint can be pounded down with a packing iron. Most plumbers these day just carry a yarning iron and a packing iron. It does a fine job.
Using Compression Gaskets For a Soil Pipe Joint
In most areas where hub and spigot cast iron is still used compression gaskets are used below ground only. This is a labor issue, some may say that yarned and poured joints are more rigid when hanging above ground but you could beef up the hangers and achieve the same results. Onward....compression gaskets are made from neoprene rubber and made in service weight and in extra heavy (extra heavy cast iron is even more archaic than traditional service weight hub and spigot.soil pipe.) The two types of gaskets are not interchangeable.
Here is how you make a compression soil pipe joint.
Preparing the Soil Gasket
Now you’re ready to prepare the gasket and piping for assembly. Using a 2” paint brush apply a thin layer of lubricant around the entire inside circumference of the gasket. Apply lubricant to the end of the pipe being inserted into the gasket.
You can drive the end of the pipe home in one of three ways.
Assembling a No-Hub Joint
Thanks again for reading from all of us at theplumbinginfo.com