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API 653 In-Service Inspection Report <br /> for <br /> Pacific Ethanol HMT Inspection <br /> Tank No. T-6101 August 6,2013 <br /> Stockton, CA Page 16 of 44 <br /> 4.3.3 SHELL CORROSION RATE CALCULATIONS <br /> When the corrosion rate is not known, the maximum interval shall be 5 years (API 653, <br /> Para. 6.3.3.2 a). When the corrosion rate is known, the maximum interval shall be the <br /> smaller of RCA/2N years or fifteen (15)years (API 653, Para. 6.3.3.2 b): <br /> RCA = tact-tmin <br /> N= tp,ev- tact/Y <br /> IUT= tact- tmin/2N <br /> Where: <br /> RCA= See Table = Difference between the measured shell thickness <br /> and the minimum required thickness in inches. <br /> N= See Table = Shell corrosion rate in inches per year <br /> Y= Years in service 6 <br /> IUT= See Table = Inspection interval for the next Ultrasonic(UT) <br /> testing, in years (not exceeding 15 years) <br /> Previous Current Minimum Next <br /> Thickness Measured Material Required Corrosion Ultrasonic(UT) <br /> Course (in.) Average Loss Thickness RCA Rate Thickness <br /> No. (t")* Thickness (in.) (In.) (in.) (in.tyr) Inspection <br /> (in.) (t t.) (M (years) <br /> fn t <br /> 1 0.250 0.255 0.000 0.116 0.139 0.0000 15 <br /> 2 0.250 0.255 0.000 0.102 0.154 0.0000 15 <br /> 3 0.187 0.187 0.001 0.100 0.087 0.0000 15 <br /> 4 0.187 0.188 0.001 0.100 0.087 0.0000 15 <br /> 5 0.187 0.191 0.000 0.100 0.091 0.0000 15 <br /> 6 0.187 0.187 0.000 0.100 0.086 0.0002 15 <br /> 7 0.187 0.189 0.000 0.100 0.088 0.0000 15 <br /> 8 0.187 0.187 0.002 0.100 0.086 0.0002 15 <br /> 9 0.187 0.192 0.000 0.100 0.091 0.0000 15 <br /> * = Original thickness data provided by client to facilitate corrosion rate calculations. <br /> RECEIVED <br /> AUG 14 2014 <br /> APiRPTNE.DOI REV 2 2326286arr6101 r(2) ENVIRIJIVn/ICIV AI_ ht_ALTI <br /> DEPARTMENT <br />