It has been believed for years by corrosion engineers that ductile iron pipe does not corrode at the same rate as steel pipe. This belief is primarily based on the assumption that ductile iron pipe corrodes slower than steel pipe because steel pipe generally contains less carbon than ductile pipe.

While it may be true that ductile pipe usually corrodes slower than steel pipe, this is assuming that the carbon is uniformly distributed and that potential corrosive hot spots do not exist. Recently, this assumption has been found to be untrue. In fact, several recent pipeline failures of ductile iron have indicated that corrosive hot spots can exist which corrode at the same rate if not faster than steel pipe.

Earlier arguments against conventional coatings being used to coat ductile iron pipe was due to the dimple peened surface of D.I. pipe. The adhesive of conventional coatings did not contact the pipe surface, leaving air pockets or voids under the coating which subsequently could corrode. Earlier tapes were constructed of adhesives which were hard and did not extrude or migrate into these surface dimples. The TEK-RAP System allows the Inner Layer, which is in contact with the entire pipe surface, to extrude or mold into these surface irregularities and completely bond to the pipe surface. The TEK-RAP Co-Extruded Ductile Iron Coating System is designed to obtain 100% surface adhesion and corrosion protection.

The TEK-RAP System contains stabilizers and inhibitors designed to resist destructive effects of ultraviolet light and soil oxidation to the polyethylene backing. Ultraviolet light deterioration to the polyethylene backing can begin if the coated D.l. pipe is left in a coating plant storage yard or uncovered in an open burial. This can cause unstabilized polyethylene to deteriorate and lose its effective strength attributes within just a few years service. TEK-RAP products are so reliable that we offer them with the industry's only 40 year guarantee when installed under TEK-RAP supervision, resulting in drastically reduced maintenance costs.