To achieve this longevity in a corrosive environment, whichever method of corrosion control is specified at the time of installation must remain effective throughout that period. One hundred years generally is considered a useful service life for the products offered by the ductile iron pipe industry. It is a passive system that is easy to install, and has been shown to protect the pipe with no costly maintenance. This tube is cut to length, slipped over each pipe section during installation, and secured in place with plastic adhesive tape or plastic strapping. It is usually supplied in tubular form in rolls. The encasement material is available in either 4 mil-thick cross-laminated high density polyethylene or 8 mil-thick low density polyethylene. This is the only method for protecting ductile iron pipe in corrosive soils that has the endorsement of an AWWA Standard. However, the method most often recommended by this industry when the need for corrosion protection is indicated is loose-film polyethylene encasement, manufactured and installed in accordance with the ANSI/AWWA standard noted above. The ductile iron pipe industry recognizes that a properly designed, installed and maintained cathodic protection system can be an effective means of mitigating corrosion. These after-installation costs can become substantially larger than the initial installation costs. The system itself is active, which means it must be inspected and maintained regularly. Installation cost of a cathodic protection system, while significant in itself, is not the only cost factor to be considered. Current is supplied in one of two ways: by impressed current from an outside power source, or through the use of buried sacrificial anodes. It requires also a joint bonding system for electrical continuity, and some means of applying an electrical current to the pipeline to make it play the role of a cathode. This method generally requires the presence of a bonded coating on the pipe. One system commonly used for corrosion protection is cathodic protection. And various methods are available to control corrosion so that a satisfactory service life for a selected pipeline product may be realized. Soil test procedures to determine if a soil is potentially corrosive to ductile iron pipe are included in the standard known as ANSI/AWWA C105/A21.5-Polyethylene Encasement for Ductile Iron Pipe Systems, Appendix A (10 point system). Corrosion is recognized as a natural phenomenon which can cause premature deterioration of pipelines in certain soi conditions. To protect the substantial investment a utility has made in an underground water or wastewater system, it is prudent for staff to consider the risk of corrosion and how best to control it.

Pipeline anode installation