THIS POLYETHYLENE SLEEVE (polywrap) is placed on Ductile Iron pipe to prevent corrosion. It does not have to be sealed watertight, but it should be installed so that no dirt or bedding material comes in contact with the pipe. All lumps of clay, mud, cinders, etc., on the pipe surface should be removed before the pipe is covered with polyethylene. If the polyethylene is damaged, it must be repaired before the trench is backfilled.
Small holes or tears can be repaired with a piece of tape placed over the hole. Large holes or tears should be repaired by taping another piece of polyethylene over the hole. Overlaps, ends, and repairs can be held in place with tape or plastic tie straps until the trench is backfilled. Other general tips for proper installation include:
- When lifting polywrapped pipe with a backhoe, use a fabric-type “sling” or padded cable to protect the polyethylene.
- When installing polywrap below the water table or in areas subject to tidal action, seal as thoroughly as possible both ends of each polyethylene tube with adhesive tape or plastic tie straps at the joint overlap. Also, place tape or plastic tie straps around the pipe at two (2) foot intervals.
- Quality of installation is more important than the actual sequence followed.
Clean all dirt, cinders, etc., from the surface of the pipe. Cut polyethylene two (2) feet longer than the pipe. Slip polyethylene over spigot end and bunch.
Dig bell holes at joint locations, lower pipe into trench and make up joint.
Move cable hoist to bell end of pipe and lift enough to slip polyethylene along pipe.
Pull polyethylene forward from previous joint over the bell and secure in place.
Pull polyethylene from new pipe over this same bell, providing a double layer of polyethylene and secure in place.
Take up slack in the tube along the pipe barrel, making a snug but not tight fit. Fold over on top of pipe and secure in place about every three (3) feet.
Make sure any tears in the polyethylene are repaired with tape or another piece of polyethylene secured over the damaged area.
Backfill the trench according to specifications, being careful not to damage the polyethylene while tamping around pipe. Backfill should not contain material that might damage the polyethylene.