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LAW/CRANDALL, INC.June 26,1997 <br />MJS&A #97192 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 of cathodic protection. <br />With the above recommendations in place, we would not anticipate corrosion problems for at least <br />20 years and probably much longer. Further, cathodic protection can be easily applied in the future, <br />if necessary. <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-0169-92. As an alternative to electrical insulation and <br />cathodic protection, place each cylinder in a plastic easing 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 />Cast and ductile iron piping do not require special protective measures such as a plastic wrap. <br />However. to avoid possibly creating corrosion problems, iron should not be placed partially in <br />contact with concrete such as thrust blocks. Use coatings mentioned above for steel or 8 mil thick <br />low-density polyethylene or 4 mil thick high-density polyethylene plastic sheets per AWWA C105 <br />to prevent such contact. Electrically insulate underground iron pipe from dissimilar metals and <br />above ground iron pipe with insulated joints.