How to Put a New Cap on a Riser Pipe

Cut through the copper pipe using a tube cutter.

Riser pipes are construction pipes (water supply, sewer, gas) that travel upward vertically through wall cavities. End caps are used to seal off a pipe end if it is no longer needed or if more pipe will be added at a later date. PVC (polyvinyl chloride) and ABS (acrylonitrile butadiene styrene) sewer pipes, as well as CPVC (chlorinated polyvinyl chloride) water-supply pipes, have end caps cemented into place. Copper end caps are soldered in place, whereas gas-pipe end caps are threaded into position.

Things You'll Need

• Handsaw/tube cutter
• Utility knife
• PVC primer
• PVC cement/CPVC cement/ABS cement
• PVC end cap/CPVC end cap/ABS end cap
• 120-grit Emery cloth
• Circular wire brush
• Soldering paste and brush
• Copper end cap
• Roll of solder
• Propane torch
• Rag
• Pipe wrench
• Yellow sealing tape
• Gas end cap
• Soapy water and brush

Instructions

PVC, ABS and CPVC End Cap

1. Cut through the PVC/ABS sewer pipe directly under the existing end cap using a handsaw. Ensure that the cut is both straight and perpendicular to the pipe. For CPVC, place the pipe in the jaws of a tube cutter directly under the end cap and squeeze the cutter's handles to cut through the pipe.

2. Scrape off any burrs from the cut pipe end using a utility knife. Brush PVC primer around the outside end of the PVC/CPVC pipe, as well as the inside of a PVC/CPVC end cap. ABS pipes/caps need no primer.

3. Brush PVC cement around the primed areas of the PVC pipe/end cap. Brush CPVC cement around the primed areas of the CPVC pipe/end cap. Brush ABS cement around the outside end of the ABS pipe, as well as the inside of an ABS end cap.

4. Push the end cap fully onto the end of the pipe. Hold the cap in place for 15 seconds while the cement dries.

Copper End Cap

1. Turn off the water supply to the copper pipe at the shutoff valve. Place the copper pipe in the jaws of a tube cutter, directly below the copper end cap. Tighten the cutter's circular blade to the side of the pipe. Rotate the cutter twice around the pipe. Retighten the cutter's blade. Rotate twice more. Repeat this process until the pipe is cut through and the end cap removed.

2. Sand around the outside end of the cut copper pipe using 120-grit Emery cloth. Push a circular wire brush into the end cap, turning it several times. Brush a thin layer of soldering paste around the sanded end of the pipe, as well as the inside of the end cap. Push the end cap onto the end of the copper pipe.

3. Unroll 8 inches of solder from its spool. Turn on a propane torch. Heat around all sides of the copper pipe/end-cap area. Touch the tip of the solder to the seam where the pipe enters into the end cap. If the solder melts, apply solder all around the seam. Wipe off excess solder and soldering-paste residue from the seam with a rag. Turn on the water supply.

Gas End Cap

1. Turn the gas off at the gas meter. Place a pipe wrench around the existing gas end cap. Turn the wrench counterclockwise to loosen and remove the cap.

2. Wrap yellow sealing tape twice clockwise around the threads on the end of the gas pipe. Screw on a new gas end cap by hand.

3. Tighten the end cap in place with the wrench. Turn on the gas supply. Mix some soapy water and brush it around the area where the gas pipe enters the end cap. If any bubbles are seen, gas is escaping. In this case, tighten the end cap with the wrench until the bubbles cease.

References

• The Family Handyman: How to Glue and Join PVC Plastic Pipe
• The Family Handyman: How to Use CPVC Plastic Plumbing Pipe
• The Family Handyman: How to Solder Copper Pipe
• HammerZone.com: Re-Routing a Natural Gas or Propane Pipe