How To Separate Cast Iron Pipe Joints

They are most frequently sealed with lead and oakum if you have cast iron drain pipes or even just cast-iron piping. Oakum is a hemp material coated in tar and inserted into the joint to seal it as the oakum expands when it gets wet, thus sealing the joint.

By casting a 1′′ thick bead of lead around the pipe inside the hub/socket, the Oakum is held in place, and the pipe joint is strengthened.

Luckily, the lead and oakum can both be removed. Although separating an old pipe with a lead joint and oakum seal like this takes skill and effort when you want to install a new bathroom. In our guide, you can learn the best ways of removing the cast iron pipe.

iron pipes

By the end, you’ll see there are options to break cast iron pipe if you no longer need the connection, or for most applications, how to remove cast iron drain pipe or cast-iron pipes that you can use for a new connection. (Learn How Long Does It Take For Loctite To Dry)

How Are Cast Iron Pipes Joined?

Oakum is a tar-coated hemp material placed into the joint to seal it. Oakum swells when wet, sealing the joint.

The Oakum is maintained in place, and the pipe joint is strengthened by casting a 1′′ thick bead of lead around the pipe inside the hub/socket.

In some remodel and retrofit projects, older cast-iron drains and vent risers are being replaced with ABS plastic pipes.

Depending on the scope of the replacement, you may have to dispose of cast-iron pipes with fittings and couplers.

By dismantling the pipes and dividing them into manageable portions, you can save money on hauling. A cast-iron snap cutter and a few hand tools are required for the process.

  1. In a cordless drill, install a 1/4-inch drill bit.
  2. Drill a series of holes in the lead seal around the mouth of the over-fitting, 1/2 inch apart, where two sections of cast-iron plumbing pipe meet.
  3. Using a flathead screwdriver, pry and remove the lead. To pry the lead out, tap the screwdriver handle with a hammer to force the tip under it.
  4. Using the old screwdriver, pry out the oakum packing beneath the lead.
  5. Pull the connector apart.
  6. Repeat on other lead and oakum-connected parts.
  7. To cut a cast-iron pipe into shorter sections, wrap the chain on the snap-cutters around it. Next, spread the cutter’s handles and hook the chain into the free handle’s notch.
  8. To snap-cut, the pipe at that point, squeeze the handles together. Then, cut additional, lengthier pipe portions into workable lengths by repeating the process.


How Do You Loosen Cast Iron Pipe Fittings?

Here you can find, what are the best ways to loosen cast iron plumbing?

  1. Spray lubricant all around the plug’s rim, getting as much as possible into the threads.
  2. Tap the plug’s rim a few times with a hammer to loosen the threads.
  3. Tighten one 18-inch pipe wrench around the drain pipe and the square nut on the top of the stopper.

The question is, then, what about if you need to repair a cast iron pipe joint?

  1. Remove corrosion from the leaded joint if there are leaks or a foul odor. The job requires you to tap the lead back inside the joint of the cast pipe using a cold chisel and hammer.
  2. Fill with cast-iron pipe repair paste.
  3. Fill any holes you see around the joint of the cast iron drain.

How Did They Connect A Cast Iron Drainpipe To Plumbing?

They’re likely sealed using a molten lead joint filled with oakum if you have cast iron drain pipes. Oakum is a tar-coated hemp material inserted into the joint to seal it. As the Oakum expands when it gets wet, it will seal the joint.

old pipe

How To Unscrew An Old Pipe?

Spray lubricant on the outside of a corroded joint and wait five to ten minutes for it to penetrate the joint of the CI pipe and dissolve the rust on the threads.

With one pipe wrench, grab the fitting you’re trying to detach; with the other, grip the pipe to which it’s connected. (Learn How To Thaw Frozen Pipes Underground)

How Do You Remove Old Lead And Oakum Joints?

If, for example, the lead and oakum joint was far enough away from wooden structures, And if you had the proper breathing equipment and high-output torches, you could melt the lead and oakum from your drain pipes in a couple of minutes.

However, such a task is impossible in your home and for the average home handyman who doesn’t have full access to complete the job. (Read Why Does My Temperature Go Up And Down)

Here is the complete way for removing cast iron pipe or sewer line to replace fittings so you can change the fitting to plastic

  1. Drilling lead every 1/4′′ or so to separate it and then chipping out each piece with a 1/2′′ or 1/4′′ chisel are two methods for manually removing the lead.
  2. It takes a long time and a lot of patience and effort to accomplish this if you wish to re-use the main pipe rather than replace the drain.
  3. You’ll need to use a right-angle drill if you don’t have complete access to the joint and it sits between joists or studs.
  4. Trim the incoming spigot end to the pipe you’re replacing about 1/2 inch away from the hub using a reciprocating saw to drill around it quickly.
  5. Reconsider if you genuinely want to keep the joint or replace the entire thing? For example, it could be easier to cut the pipe or sewer line and hook it up to a flexible coupling rather than remove more drywall panels to get full access to complete the job.
  6. Changing drywall is simple compared to patiently chipping away the lead from one of these junctions with a drill bit.
  7. Of course, breaking cast-iron pipe cleanly needs a specialist pipe breaker tool that you would have to rent.
  8. Choose the cheapest drill bits if you absolutely must save and reuse the joint owing to space or other constraints.
  9. This is not the time to use your high-end titanium carbide drill bits. Steel drill bits should be tougher than lead, yet as soft and non-brittle as feasible.
  10. Otherwise, if you drill lead and apply any sideways pressure to the drill bits, they will shatter because of their extremely high hardness.
  11. This leaves a solid chunk of exceptionally high hardness metal embedded in your lead seal around your cast iron drain pipe, which is extremely difficult to remove.
  12. Use a reamer, not a drill bit! The inside of your hub will still have a thin ring of lead all the way around after chipping away enough lead to removing the inner pipe.
  13. Remove all the Oakum with pliers, scrapers, or an angle grinder with a cutting wheel, as Oakum will catch fire if it gets too hot and is exposed to air.
  14. You can carefully melt the remaining lead with a tiny blowtorch at this stage.
  15. As drops of lead fall from the ring, use the torch on the inside of the pipe and have a fire extinguisher and a bucket of water nearby.
  16. The cast iron pipe will eventually become hot enough to melt the lead in contact with it.
  17. You can now pry the entire lead ring with a screwdriver or chisel out of the pipe.
  18. You now have a clean hub connection into which you can fit your donut or Fernco coupler. First, check the fit and make sure everything is in place.
  19. Then, to make it easier to hammer the Fernco coupling in, put some cooking oil into the cast iron pipe hub.
  20. Apply a bead of silicon caulk around the circumference of the donut.
  21. Using a heavy hammer, pound the donut into place.
  22. You can now chamfer the PVC pipe to make it easier to insert into the seal/donut.
  23. Make inch markers on your PVC pipe to see how far it’s gone through the seal.
  24. Spray the inside of the donut with more cooking oil, place a bead of silicon caulk around the PVC pipe, and hammer in your new pipe.
  25. It’s now only a matter of gluing several PVC sections together with PVC solvent and cement to reach your drain.

How Do You Remove Cast Iron Plumbing?

If you’ve never handled old cast dirt pipes, be cautious of their weight.

  1. Block the underground drainage system’s access.
  2. Use an angle grinder or a soil pipe cutter to remove a small section of the soil pipe.
  3. The pipe is usually not loaded, so you can cut a small part out without affecting the overall stack.
  4. After removing this portion, fasten it quickly. There’s a considerable risk you’ll create debris as the stack falls from the wall, and if it gets into the drainage system, it’ll cost a fortune to remove.
  5. The first method is brute force. In most cases, the cast wastewater drain pipes may be pried out of the wall with a lump hammer and a firm footing.
  6. Being safe is vital, so don’t use this method if you’re unsure about what you’re doing or if everything around you is secure.
  7. Using a grinder or pipe cutter to remove the soil pipes is better.

This takes longer, and you should not underestimate the weight of each small section of drain pipes.

The iron waste pipes you’re removing will eventually connect to clay soil pipes in the underground drainage system. So, to make things neat, connect directly to this clay pipe.

Though the clay pipe connection is only a few inches deep, this requires some digging. Allow enough room to cleanly cut the iron-clay joint, not clog any drainage lines.

Now that your home is free of old pipes, you may use your original schematics to help plan your new stack. (Learn Repair Screw Holes In Drywall For Reuse)

Work your way along the building, starting with any toilet pan connectors and considering any wastewater collection sites (bath, sinks, shower, washing machine, etc.).

You can choose between push-fit soil pipe and solvent-weld products at this stage.

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