Working Cast Iron Pipe

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Although plastic pipe or large copper tubing with soldered joints is used a lot now for home drain, waste, and vent systems, there is still a place for traditional cast iron pipe. Older homes, of course, have cast iron DWV systems that occasionally need repair. And some codes say that because of its strength, cast iron should still be used for underground installations where heavy pressures would crush alternative pipe. Even though cast iron is very heavy and inconvenient to install and repair, it's also very durable and trouble-free once it’s in place.

Pipe and Fittings

Cast iron pipe comes in 5- and 10-foot lengths and in diameters of 2 inches and larger; 1½-inch hubless pipe is now available in some areas. For home use, 2-, 3-, and 4-inch pipe is the most common. The pipe and fittings come in two types. The older type, joined with oakum and molten lead, is called hub or hub-and-spigot pipe. The newer hubless pipe and fittings are joined with special clamps and a rubber sleeve.

Hub pipe usually has a hub on one end and a spigot on the other. The spigot of one section fits into the hub on the next. You can buy double-hub sections for cutting when you need pieces shorter than the standard 5- and 10-foot sections. When you cut the length you need from a double-hub section, it leaves you another usable piece instead of a long piece of wasted pipe. Of course. the ideal way to cut down on waste of both time and pipe is very careful planning. If you are planning a new installation (or even a slightly complicated repair), draw it out carefully and try to figure out how to do it with standard lengths as much as possible.

An installation of hubless pipe automatically avoids this kind of waste because all of the pipe and fittings have smooth, even ends. The ends just butt together in side a neoprene sleeve that's held tightly in place by a stainless steel clamp. It is becoming rare now, but building or plumbing codes in some localities still prohibit the use of hubless DWV pipe. Be sure to check before you use it.

Both hub and hubless fittings come in a seemingly endless variety. Elbows are called bends in the DWV sys tem. They come in several more angles than water sup ply pipe does. The 1/16-, ¼-, ¼-, ½-, and ¼-inch bends are at angles of 22½, 45, 60, 72, and 90 degrees respectively. They also come in short, regular, and long, which indicates the sweep or radius of their curve, Closet bends are special fittings designed to connect the toilet or water closet to the drain system. These are made in several styles; those required by your local codes are usually stocked by the dealers in your area. There are also reducers, increasers, and offset bends. A special flange called a closet flange goes between the toilet and the closet bend.

img_41 Hub-and Spigot Fittings: Closet flange; Closet bend; Hubless Fittings

Tees and wyes come single or double, with the branches on the same plane or to the side and with single and double side inlets for the connection of smaller drains or vent pipes. The tees and wyes come in two types: sanitary fittings designed to carry waste material and straight fittings to carry gas only in the vent part of the system. Cleanout or test tees have one branch threaded with a plug. These are used by the inspector to test the system and as permanent cleanouts.

Measuring and Cutting

Hub pipe and fittings are measured from hub face to hub lace. Then you add the amount of pipe that goes into the fitting to get the total length of the pipe you’ll need. Hubless pipe and fittings are measured end to end, less the width of the separator in the neoprene sleeve, usually about ‘/e inch. Mark the place to cut with chalk or crayon. Draw a line all the way around the pipe to be sure you cut it off square.

Both hub and hubless cast iron pipe are cut with the same methods. If you are repairing a leak or adding to a system and need to cut a pipe that's already installed, you’ll need a pipe cutter. It is called a soil pipe cutter and can usually be rented.

Img_42 Cutting Cast Iron Pipe: Hold the blade guard out of the way. Pivot the saw on the front edge of the base plate. Adjustment knob. Cast Iron pipe that's already installed can be cut with a soil pipe cutter.

To cut loose pipe with a portable power saw, set a metal-cuffing blade to cut 1/2-inch deep and have a helper turn the pipe as you cut,

A soil pipe cutter works much like the pipe cutter or tubing cutter described. It has a pipe handle and two or more steel cutting wheels. The pressure is put on the cutting wheels by turning a knob. You tighten the knob and rotate the cutter around the pipe alternately until the pipe snaps off.

If you need to cut loose, uninstalled pipe there are several ways, One is to put the pipe in a vise and use the soil pipe cutter. Other methods involve a portable power saw, hacksaw; and hammer and chisel.

To use the power saw, you’ll need a metal-cutting blade and a helper. Set the blade so it cuts about ½-inch deep. Have your helper turn the pipe slowly as you follow the chalk line with the saw.

Img_43: Cuffing cast iron pipe: To cut loose pipe, first score it on the cutting mark with a hacksaw. Then hold a chisel on the scored line and tap it lightly. Move around the pipe three or four times until it snaps off.

You can also simply use a 3 cold chisel and a 12-ounce ball peen hammer. Lay the pipe on boards or a mound of dirt so it's well supported, Hold the chisel on the chalk line and tap it lightly. Move around the pipe until it's scored all the way around. Then go around again and again using slightly harder blows for each revolution. The pipe will usually snap off about the third or fourth time you go around. Go slowly until you get a feel for what you are doing. If you hit too hard, the pipe may crack somewhere besides on your chalk line. The hammering method can be speeded up by scoring the pipe first with a hacksaw. Make a cut about Via-inch deep all around the cut line, Then go around the pipe once or twice, tapping on the saw cut with the hammer.


The traditional way to join hub pipe is with a plumber’s furnace or some other way of melting lead, a ladle, a caulking tool, a joint runner, and some oakum and lead. This potentially dangerous method can be avoided al together by using lead wool instead of molten lead. If you use the lead wool method, insert the spigot end of one piece of pipe into the hub of the next piece. Use the caulking tool to pack oakum into the joint until it's about one inch from the face of the hub. Then fill the remaining space with lead wool that you pack tightly with a caulking tool.

If you opt for the molten lead method, follow these instructions. If the pipe is vertical so the hub is straight up, you won’t need the joint runner. If the hub is tipped side ways. secure the runner around the joint with its clip. Have the opening of the runner at the highest point on the rim of the hub.

Alter packing the joint, melt the lead, dip it with the ladle, and pour it into the joint until the hub is full to the rim. Let the lead cool and then use the caulking iron to pack it down firmly With either the lead wool or molten lead method, you should have two caulking irons—an outside and an inside iron. Use them alternately to pack the lead against the hub and the spigot.

Img_44 Joining Cast Iron Pipe

An inside caulking iron is beveled to pack the lead against the spigot.

An outside caulking iron is beveled to pack the lead against the hub.

1. Pack the joint with oakum to within one inch of the hub rim.

2. Fill the rest of the joint with the lead wool or molten lead.

3. Pack the lead tightly with caulking irons.

WARNING: The slightest bit of moisture, when hit by molten lead, turns instantly to steam. It expands quickly— explodes actually—and can throw molten lead all around. Be sure that your tools are dry and there is no moisture in the joint or oakum when you pour in the lead.

If you should suspect that there might be moisture in the joint, heat it with a propane torch to dry it before you pour the lead. Wear safety glasses or goggles.

To join hubless pipe, you’ll need a sleeve and clamp for each joint. These are sold in sets. The only tool you’ll need is a stout screwdriver, Place the neoprene sleeve over the end of one pipe, Slip the clamp onto the other pipe and slide the pipe into the neoprene sleeve. Center the clamp over the sleeve and tighten the screws on the clamp. That’s all there is to it.

Joining Hubless Pipe

Hubless pipe

If a cleanout is leaking, unscrew it...

1. Slide the ends of the pipe into the neoprene sleeve so they are snug against the center ridge. Band clamps. Neoprene sleeve. Stainless steel sleeve.

Center ridge

2. Center the stainless steel shield over the sleeve and tighten the screws.

Hubless pipe

Sealing a Leaky Cleanout: clean the threads with a wire brush; paint on some pipe joint compound, and replace the cleanout.


Plumber’s tape is made of copper, galvanized iron, and plastic. It should only be used in contact with like material.

Clamp for supporting vertical pipe against a wall; Floor clamp for supporting vertical pipe, like a stack, within a wall; Split-ring hanger for the support of steel for cast iron pipe (also made of plastic for plastic pipe)

Pipe Supports

Horizontal runs of DWV pipe must be supported with approved hangers at designated intervals according to building and plumbing codes. The spacing for supports varies with the kind of pipe. Here are the usual standards. Check your local code for specifics.

Hub cast iron pipe must be supported at intervals no greater than 5 feet. Hubless pipe must have a support at every joint. Threaded iron pipe must have a support every 10 feet or less. Soldered copper pipe and plastic cold- water pipe must have a support at 8-foot and 4-foot intervals respectively. Plastic hot-water piping needs continuous support.

The interval between supply pipe supports isn't usually spelled out in the codes, but they must be secured to the building structure to minimize the movement of the pipe from hammering (sudden starting or stopping of the water in the pipe) and from the expansion and contraction of the piping itself due to temperature fluctuations.

There are many manufactured bulk materials and gadgets to support and secure pipe. Plumber’s tape, which comes in 10-foot rolls, is probably the most universally available material. It is pliable, galvanized iron or copper-plated strapping. It is perforated along its entire length so nails, screws, or bolts can be easily stuck through it. Do not use this metal support material for plastic pipe.

Other hangers, straps, brackets, and supports vary in form from manufacturer to manufacturer and from store to store. A sampling of these is shown in the drawing.

Condensed moisture or dampness between unlike metals causes galvanic action even on the outside of pipes. Therefore, you should always try to match the metal of the support with the metal of the pipe. Use galvanized iron or steel supports for iron pipe and copper or brass supports for copper or brass pipe. There are also many hooks, hangers, and other supports for pipe and tubing that are coated with a rubberlike plastic or have a felt-like fiber insert. These can be used freely on all kinds of pipe. Since the diameters are similar, most plastic-coated devices made to support copper tubing can also be used to hold plastic piping.

Pipe Support Devices: Pipe straps; Snap-lock hanger for metal or plastic pipe and a perforated plastic angle for attaching it to an overhead beam or joist; Plastic-coated. An especially strong hanger for larger sizes of cast iron or steel pipe. Metal hanger for cast iron or threaded pipe

Tools for Working with Cast Iron Pipe

Hacksaw, ball peen hammer, and cold chisel. This is probably the best choice of methods to cut cast iron pipe before it's installed.

Portable power saw with a metal-cutting blade. To cut cast iron pipe with a portable power saw, you’ll need a metal-cutting abrasive-wheel blade, a pair of safety glasses, and a helper.

Soil pipe cutter. This tool is absolutely necessary for cut ting cast iron pipe that's already in place. It is probably not worth your while to buy one, as they can be rented at most equipment rental outlets, If the pipe you want to cut is unattached, one of the other methods of cutting is probably better.

Plumber’s furnace and ladle. Here is another item you can rent for an occasional job. It is used to melt the lead to join hub-and-spigot sewer pipe, Joint runner. This device holds molten lead in the joint when you join horizontal sections of hub-and-spigot pipe.

Caulking tools. There are several tools used to pack the oakum and lead in to the joint of hub-and-spigot pipe. They come both separately and in combination—that is. a different tool on each end of a single handle. The in side caulking iron and outside caulking iron will be all you’ll need for most jobs. The yarning iron, packing iron, and pickout tool are all variations of the caulking irons and will make this job a little easier if you are making very many joints.

Oakum and lead or lead wool. Oakum is the yarn-like material that, when packed tightly and exposed to moisture. expands to seal joints or cracks. The lead in a hub- and -spigot joint gives the oakum a firm backing against which to expand.

No-hub fittings. These are neoprene sleeves and stain less steel clamps designed to join hubless cast iron sewer pipe. These kinds of joints are easier and quicker to make and probably just as durable as hub-and-spigot, oakum and -lead joints.

Cast Iron Pipe Tools: Cold chisel; Nut driver; Lead; Outside packing iron; Inside packing iron

Sunday, May 13, 2012 1:42 PST