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API 653 In-Service Inspection Report <br /> for <br /> Pacific Ethanol HMT Inspection <br /> Tank No. T-6105 August 7,2013 <br /> Stockton, CA Page 16 of 45 <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—tmirt <br /> N= tprev—tact f Y <br /> 1 UT= 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 /> 1UT= 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. (tp� )* Thickness (in.) (in.) (in.) (in./yr) Inspection <br /> (in.) [tm,,,) (N) (years) <br /> Veer ru <br /> 1 0.375 0.385 0.000 0.319 0.065 0.0000 15 <br /> 2 0.375 0.383 0.000 0.254 0.129 0.0000 15 <br /> 3 0.250 0.253 0.000 0.172 0.080 0.0000 15 <br /> 4 0.250 0.258 0.000 0.113 0.145 0.0000 15 <br /> 5 0.250 1 0.251 TO.000 0.100 0.151 1 0.0000 15 <br /> * = Original thickness data provided by client to facilitate corrosion rate calculations. <br /> RECEIVED <br /> AUG 14 2014 <br /> APIRPTNE,DOT REV 2 23262566/T-61 05r(Rev 1) 11/6Q0131:43 PM <br /> ENVIRONMENTAL HEALTH <br /> DEPARTMENT <br />