Whether you're working with PVC, ABS or cast iron, Mission couplings are essential for fitting a section of pipe into an existing run of waste line or vent. Installation is simple.
Buy and assemble matching replacement parts. Mark the cutting points on the old drains about 1/2 in. larger than the replacement.
Cut the plastic at a right angle using a fine-tooth saw and remove the assembly.
Slide the mission coupling onto one pipe and cement plastic couplings onto the other two pipes.
Center the mission coupling over the third joint and tighten the bands firmly.
When repairing a section of pipe in an existing run, don't try to cement (solvent-weld) all the new couplings. Most drain systems use rigid pipes fairly large in diameter. You can't flex them enough to slide on that last fitting and get it to seat fully. Rather than struggle with cement, pros use a “mission” coupling (Photos 3 and 4) that clamps over the last joint. Even though a mission coupling costs more than a plastic coupling, the extra cost is worth it. Sometimes, pros will even use two mission couplings in tight situations. Photos 1 – 4 walk you through the process. Be sure to buy couplings with full steel sleeves, and make sure mission couplings meet code requirements in your area.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.