Tricks for Splicing Plastic Drain Pipe

Updated: Nov. 18, 2019

Save time and trouble with Mission couplings

FH07MAR_SPLPIP_03-2Family Handyman
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.

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Installing a Mission Coupling

Photo 1: Mark cuts

Buy and assemble matching replacement parts. Mark the cutting points on the old drains about 1/2 in. larger than the replacement.

Photo 2: Remove pipe

Cut the plastic at a right angle using a fine-tooth saw and remove the assembly.

Photo 3: Install new pipe

Slide the mission coupling onto one pipe and cement plastic couplings onto the other two pipes.

Photo 4: Finish up

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.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • 4-in-1 screwdriver
  • Hacksaw

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Mission coupling
  • PVC or ABS glue
  • Replacement pipe