b'Design Example 2Corrosion Life of ECP Steel Pier PipeStructural and Soil Details: thesoilstudyconfirmtheengineersconcern ThissettledstructurewaspresentedasDesign about corrosion effects of the earth on steel.Examples 1 and 2 in Chapter 8, but now there is a 2.Estimated Life Galvanize Loss: The firstconcern about corrosion. calculationestimatestheaveragelifeforthe When discussing this project with the engineer, galvanized coating on the pier pipe in soil with ahe mentions that consolidation of a layer of weak resistivityof700ohm-cm.UseEquation1soilcausedthesettlement.Uponfurther introduced in Chapter 8 to estimate the averageinvestigations of the soil data, it is learned that lifeofthe millpre-galvanizedsheetcorrosionthereisapproximatelysixfeetofuncompacted protection coating.loose fill with Standard Penetration Test values,N = 1 to 3 blows per foot. Equation 1 - Corrosion Life Zinc: Below six feet of fill soil there is firm clay with CL G= G / [0.25 - 0.12 log 10(R/150)]SPT values exceeding N = 5 blows per foot. Where: CL G= Weight loss (oz/ft 2 ) Furthersoiltestingsuggestedthatcorrosion G = 0.32 oz/ft 2 (High Speed Mill Galvanize)might be an issue on this job.The soil resistivity R = 700 ohm-cm (Soil resistivity)at five feet below grade was 700 ohm-cm and at a Determine CL Gusing Equation 1:depthoftenfeetbelowgradetheresistivityclimbed to 1,500 ohm-cm.Soil testing reported CL G = 0.32 / [0.25 - 0.12 log 10(700/150)]averaged value for pH = 5.5 down to ten feet. = 0.32 / [0.250.12 log 104.67] The underpinning specified in Design Example 2 = 0.32 / [0.250.080] =wasECPPPB-350-EPSSteelPierPipeatthe = 0.32 / 0.170 = 1.88 yearssettled area. CL G= 1.9 yearsECPCorrosionLifeAnalysis: Theequations 3.Estimated Life Steel Loss: The formulaprovided in the previous chapter will be applied for estimating average time for 10% loss in steelto estimate the average life expectancy of the hot wallthicknessisgiveninEquation2fromdipgalvanizationandlossof10%ofwall Chapter 8:thicknessofthe3-1/2inchdiameterby 0.165inch wall corrosion protected tube. Equation 2 - Corrosion Life Steel ShaftThe result from this analysis provides an estimate CL P= W S-10% / K C Where:of average life expectancy.When dealing with CLP = Life expectancy of steel tube (years)W S-10% = 10% steel pier weight loss (oz/ft 2 )soilconditionsonajobsite,thereisalwaysa K C = Corrosion loss per year- oz/ft 2degreeofvariabilityintheperformancelifeofsteel piles.W S-10% istheamountofsteellossequaltoPlease review the shaded box presented at the 10%ofthewallthicknessof the3-1/2inchbeginning of Design Example 1 above. diameter by 0.165 inch wall pier pipe. W S-10%is determined using Equation 3:Thecorrosionlifeanalysiswillconsistoftwo W S-10%= 10% [t/12] x 489.6 lb/ft 3x 16 oz/lbparts;firstisthecorrosionliveanalysisofthe W S= 0.10 x [0.165/12] x 489.6 x 16zinc coating on the pier pipe, and second is the W S= 10.8 oz/ft 2corrosion loss of 10% of the wall thickness of theK Cis the corrosion loss rate that is determinedpier pipe. by usingGraph3 -Chapter 8,alsoshown1. Soil Report and Corrosivity: A soil study of below.the five feet of fill material suggested that this The highest rate of corrosion within the fill soilsoil may be corrosive. Reviewing Tables 3 and 4 will occur at the lowest resistivity - 700 ohm-cm.in Chapter 8, a Corrosivity Score of 8/9 was Read horizontally from the left side of Graph 3found. Thisfillsoilcanbeconsidered (shown below) to the point that represents a pHModerately Corrosiveto Aggressively = 5.5.Then read directly down to determine theCorrosive.The Standard Penetration Test soil loss in weight of steel per year.A corrosion lossanalysis of the stratum of fill reported N = 1 to of 0.45 oz/ft 2per year is determined.3blowsperfoot,thepH=5.5andthesoil K C= 0.45 oz/ft 2per yearresistivity was 700 ohm-cm.These values fromECP Technical Design ManualCorrosion Life Design Examples2021 Earth Contact Products, L.L.C.2021-09 Chapter 9Page 163 All rights reserved'