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GEOTECHNICAL PROFESSIONALS, INC.August 12,1997 <br />MJS&:A #97246 Page 3 <br />CORROSION CONTROL <br />The life of buried materials depends on thickness, strength, loads, construction details, soil <br />moisture, etc., in addition to soil corrosivity, and is, therefore, difficult to predict. Of more practical <br />value are corrosion control methods that will increase the life of materials that would be subject to <br />significant corrosion. <br />Steel Pipe <br />Abrasive blast underground steel utilities and apply a high quality dielectric coating such as <br />extruded polyethylene, a tape coating system, hot applied coal tar enamel, or fusion bonded epoxy. <br />Bond underground steel pipe with rubber gasketed, mechanical, grooved end, or other <br />nonconductive type joints for electrical continuity. Electrical continuity is necessary for corrosion <br />monitoring and cathodic protection. <br />Electrically insulate each buried steel pipeline from dissimilar metals, cement-mortar coated and <br />concrete encased steel, and above ground steel pipe to prevent dissimilar metal corrosion cells and <br />to facilitate the application ofcathodic protection. <br />Apply cathodic protection to steel piping as per NACE International RP-0169-96. <br />As an alternative to dielectric coating and cathodic protection, apply a 3/4 inch cement mortar <br />coating or encase in cement-slurry or concrete 3 inches thick. <br />Hydraulic Elevator <br />Coat hydraulic elevator cylinders as described above. Electrically insulate each cylinder from <br />building metals by installing dielectric material between the piston platen and car, insulating the <br />bolts, and installing an insulated joint in the oil line. Apply cathodic protection to hydraulic <br />cylinders as per NACE International RP-0169-96. As an alternative to electrical insulation and <br />cathodic protection, place each cylinder in a plastic casing with a plastic watertight seal at the <br />bottom. <br />The elevator oil line should be placed above ground if possible but, if underground, should be <br />protected as described above for steel utilities. <br />Iron Pipe <br />Encase cast and ductile iron piping in 8 mil thick low-density polyethylene or 4 mil thick high- <br />density, cross-laminated polyethylene plastic tubes or wraps per AWWA Standard C 105 or coat <br />with a high quality dielectric coating such as polyurethane or coal tar epoxy. As an alternative, <br />encase iron piping with cement slurry or concrete at least 3 inches thick surrounding the pipe. <br />Bond all nonconductive type joints in pressurized lines, such as waterlines, for electrical continuity.