Before the 1950’s, the traditional way of connecting cast iron pipe was the hub and spigot method. Using burners, oakum, joint runners, and specialized tools, a highly trained plumber would pour melted lead into a fitting to join and seal it. This process took years of practice and apprenticeship in order to perform correctly.
No-Hub Couplings Changed the World of Plumbing
With a neoprene rubber gasket, a stainless-steel shield, and a few clamps, the same cast iron connections could be done faster and with far less training. On top of that, this new process eliminated the need to work with melted lead. By the 1960’s, plumbers found that the no-hub coupling was a superior product that was passing the test of time.
With the advent of ABS and PVC, cast iron is no longer the most common material for new piping. However, there are still many cast iron piping systems in use today. Since they are so durable, cast iron pipes can often be found still occupying their original installations in older buildings.
Some cast iron is being installed new as well. For instance, some designs may require cast iron for its lower flow noise, especially in multi-story residential projects. Also, some local building codes still specify cast iron for various applications. Whether repairing an old cast iron pipe or building a new commercial project, no-hub couplings are a safe and efficient option.
Components and Tools Needed
- Neoprene rubber gasket with stainless-steel shield
- Interlocking worm clamps
Note: Depending on the type and size of the coupling, you will need between 2 and 6 worm clamps.
- Torque wrench
Note: Light-duty couplings should be torqued to 60 inch-pounds and both medium and heavy-duty couplings should be torqued to 80 inch-pounds.
- Hex-head socket bit
Note: You will need a 5/16” bit for light or medium-duty couplings and a 3/8” bit for heavy-duty couplings.
Step 1: Slide the worm clamps over one end of the pipe and keep them handy.
Step 2: Push the rubber gasket and shield onto one end of the pipe. The center lip on the inside of the gasket will provide a natural stop.
Step 3: Fold down the rubber gasket to the center lip.
Note: With Thermafit Industries’ revolutionary coupling, there is no need to fold the gasket or even separate it from the shield. This will save you time and keep your fingers safe from sharp edges. With our patent-pending design, Steps 3, 5, and 6 are not necessary at all!
Step 4: Center the pipes together and push the second pipe end into the connection.
Step 5: Fold the rubber gasket back onto the other end of the pipe.
Step 6: Slide the shield over the rubber gasket.
Step 7: Slide the worm clamps over the shield. You may need to loosen the worm clamps to get them to slide easily.
Step 8: Finally, tighten the worm clamps using a torque wrench with a hex-head socket bit. Make sure you do not exceed the recommended torque on the screws. If you torque them too tightly, the excess pressure may eventually weaken and crack the pipe.