PVC

PVC stands for polyvinyl chloride and is used mainly in commercial, industrial and institutional plumbing drainage systems. PVC is also used in ground work in residential, and in septic fields. The PVC in septic systems is white with holes in the pipe to allow the effluent discharge to run into the field. The pipe in residential ground work is white (called drain line) and is thinner walled than the gray PVC, and is used only in the ground. When you come up out of the ground you need to convert over to ABS pipe with a sleeve in an ABS fitting and transition cement.

In commercial, institutional and industrial buildings the PVC pipe in the ground for drainage can be white, gray, or green. And for water lines the pipe will be blue. Not to be confused with pex water lines that may be white, blue or red. These waterlines are joined with a rubber gasket only and then have cement poured around any 45 or 90 or tee to prevent the lines from coming apart from the high pressure and possible water hammer. The drain lines are held together by the ground only and use rubber gaskets to keep from leaking. These are for drain lines of 6 inches or larger. Smaller than 6 inches will use PVC cement.

Joining PVC

To join PVC pipe to the fittings you will use a primer and cement. The primer is used to clean the PVC and the cement in then used to join the pieces together. Some areas require you to use purple primer instead of the clear primer so it is obvious to the inspector that primer was used. The PVC cement comes in gray and clear. While the transition cement (PVC to ABS) is white in color.

To hang PVC on the horizontal the code says you must have supports every four feet and at every joint or change of direction. Check your local codes to ensure that your supports are correct. To support the pipe you can use galvanized strap or clevice hangers.

To join PVC to cast iron the best method is to use a fernco. A rubber sleeve with two gear clamps to hold the pipes together and keep from leaking. Some people will use a MJ (mechanical joint) clamp, this will work, but I prefer the fernco as this is just the more professional way to do the job.