AWWA C105/A21.5-99

This standard covers materials and installation procedures for polyethylene encasement to be applied to underground installations of ductile-iron pipe. This standard also may be used for polyethylene encasement of fittings, valves, and other appurtenances to ductile-iron pipe systems. The purpose of this standard is to provide purchasers, manufacturers, and constructors with the minimum requirements for polyethylene sheet and tubes to be used for external corrosion protection of buried ductile-iron pipe, fittings, and appurtenances. The major revisions in this edition of the standard are as follows: Section 4.1, Materials, has been expanded to include 4-mil, high-density, cross laminated (“HDCL”) polyethylene; Class B (colors) was added to Sec. 4.1, Materials, to allow the purchase of colored polyethylene; Table 1 was modified to reflect reduced tube widths comparable with push-on joint pipe and fittings. The size range was also expanded to include 60- and 64-in. (1500- and 1600-mm) pipe; A recommendation that circumferential wraps of tape be placed at 2-ft (0.6-m) intervals along the barrel of the pipe for installations below the water table and/or in areas subject to tidal actions was added to Sec. 4.3.1; A paragraph was added to Sec. 4.3.6 to indicate that the preferred method of making direct service taps on polyethylene-encased pipe is to apply two or three wraps of tape around the encased pipe to cover the area where the tapping machine will be mounted. The tap is then made through the tape and polyethylene. An illustration of this procedure (Figure 5) was also added.