Joining Hub-and-Spigot Pipe:
Hub-and-spigot pipe can be joined by two methods: the compression joint or the lead and oakum joint.
Click on each type of joint to find out more:
1. Compression Joint
2. Lead and Oakum Joint
Compression joints are a fast method of joining cast-iron and fittings. They can absorb vibrations and be deflected or bent up to 5 degrees. Compression joints require the use of pipe and fittings that do not have a bead on the spigot end.
To make a compression joint, follow these steps:
1. Clean the neoprene gasket in the hub.
2. Insert the gasket in the hub.
3. Apply a rubber lubricant to the inside of the gasket.
4. Force the spigot end of the pipe into the gasket using puller tools.
Lead and Oakum Joints
Lead and oakum joints are strong. These joints are made by pouring molten lead over oakum fiber to form a watertight seal between the two pieces of pipe, and then caulking the joint after the lead has cooled and solidified. The solidified lead that results from the heating process is called slag.
Creating lead and oakum joints also requires many special tools such as, running rope, spring clamp, propane melting furnace, lead pot and ladle, iron (yarning iron, caulking iron, pickout iron).
Joining No-Hub Pipe:
To join no-hub pipe, use couplings. Couplings have three components: a gasket, a stainless steel shield, and clamps.
The gasket is made of neoprene. The gasket is flexible, with a ridge on the inside diameter to control the distance the gasket can be slipped onto the end of no-hub pipe. The shield and clamps are made of stainless steel. The corrugated stainless steel shield surrounds the neoprene gasket, with two clamps around the gasket and shield.
Joining no-hub pipe requires two special tools: a soil pipe cutter and a torque wrench.
Testing Cast-Iron Piping Installations
Cast-iron piping installations of vent and drainage systems can be tested by a hydrostatic test (water test), air pressure test, smoke test, and peppermint test.
Air and water testing can be performed at the rough-in stage. Smoke and peppermint testing must be performed after final installation.
Check the local plumbing code to determine which test should be applied. If possible, test only one floor at a time.
Plug all openings except for one vertical pipe. Extend the vertical pipe at least 5 feet higher than the horizontal drain piping. If the code requires a 10-foot head of water, extend the pipe at least 10 feet. Fill this pipe with water. Check for any leaking joints in the system.
Air Pressure Test
Air testing is similar to water testing except that the pipes are filled with compressed air. The system should generally be pressurized to a maximum of 5 pounds per square inch (psi). Use a pressure gauge at the test plug to determine whether any pressure has been lost.
While cast-iron pipe and fittings joined with compression joints or couplings should have a reduction in air pressure during a 15-minute test, a reduction or more than 1 psi indicates a failure of the system.
A smoke test involves filling the traps with water and adding a thick smoke into the vent system. The stack should be closed when the smoke appears at the roof opening. A pressure of 1 inch water column is needed throughout the smoke test. The system passes the test if no smoke is visible at any connection in the system.
If plumbing inspector decides that a smoke test cannot be used, use a peppermint test.
To conduct a peppermint test, add 2 ounces of peppermint oil into each roof opening of the system. After adding the peppermint oil, add 10 quarts of hot water (160F). Seal each terminal. If you can smell peppermint at any point in the system, you have identified a leak.
Inspectors will check the installation for the following points:
• All codes related to the pipe installation have been complied with.
• There are no cross-connections, and defective or inferior materials, or poor craftsmanship used for the installation.
Because it is important to inspect the joints in the piping system visually, the inspection must be done before the pipes are covered.