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API 653 In-Service Inspection Report <br /> for M <br /> Pacific Ethanol HMT Inspection <br /> Tank No. T-6106 August 8,2013 <br /> Stockton, CA Page 16 of 46 <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 RCA12N years or fifteen (15)years (API 653, Para. 6.3.3.2 b): <br /> RCA = fact—tmin <br /> N= tprev— tact/Y <br /> 1UT= 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 /> i <br /> Previous Current Minimum Next <br /> Thickness Measured Material Required Corrosion Ultrasonic(UT) <br /> Course (in.) Average Loss Thickness RCA Bate Thickness <br /> No. (rp.,)* Thickness (in.) (in.) (in.) (in./yr) Inspection <br /> (in.) 0.0 (M (years) <br /> r, ►., <br /> 1 0.375 0.384 0.000 0.319 0.064 0.0000 15 <br /> 2 0.375 0.384 0.000 0.254 0.129 0.0000 15 <br /> 3 0.250 0.256 0.000 0.172 0.084 0.0000 15 <br /> 4 0.250 0.254 0.000 0.113 0.141 0.0000 15 <br /> 5 0.250 0.254 0.000 0.100 0.153 0.0000 15 <br /> * = Original thickness data provided by client to facilitate corrosion rate calculations. <br /> t REC <br /> L) <br /> AUG 14 2014 <br /> APIRPTNE.DOT REV 2 23262868rT-6106r(Rev 1) Ef"F1 jE-Wrn L HEgLTfj <br /> DEPARTMENT <br />