Laserfiche WebLink
TEST PROCEDURES <br /> UNDERGROUND TAMC EVALUATION <br /> The collection of accurate corrosion data requires attention to test procedures <br /> and equipment to ensure the retrding of reproducible data. Test methods <br /> incorporated in the investigation for the evaluation of corrosion on underground <br /> tanks and the design of cathodic protection systems include the fallowing: <br /> Soil Resistivity <br /> Structure-to-Seal Potential <br /> Stray Current <br /> pH <br /> ChIcride Inn <br /> Sulfide Ion <br /> Moisture Content <br /> Hydrocarbon Concentration <br /> L Soil Resistivity <br /> Resistivity is a common parameter for evaluating the corrosiveness of sail. <br /> Resistivity is the inverse of conductivity and is measured in the units of <br /> ohm-centimeters. Corr sivity is often an inverse f act on of resistivity with low <br /> resistivity sails usually more c=osive than high resistivity sails. Serious <br /> corrosion can also be associated with high resistivity soils, particuh-Lrly where <br /> the soil. composition is not uniform. Variatiorns in resistivity indicate variations <br /> in composition which are conducive to galvanic corrosion. <br /> Resistivity profiles in test hales are performed using a 3/8" diameter by 1 foot <br /> hong single probe. The length and dimensions of the probe erasure optimum <br /> contact with the surrounding urAisturbedi soil which is often not accomplished <br /> with using conventional single probe apparatus. <br /> 1 <br />