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API 653 Out-of-Service Inspection Report <br /> for <br /> J.R. Simplot Inspection <br /> Tank No. 8 August 27-28,2008 <br /> Lathrop, CA page 25 of 54 <br /> 5.3 BOTTOM INSPECTION <br /> The tank bottom plates were inspected utilizing MFL, UT and VT inspection methods. <br /> The bottom was inspected for the detection of both internal and underside metal loss. <br /> Areas identified by the MFL as exceeding or closely approaching the critical thickness <br /> were quantified by UT and pit gauge measurements. Recording criteria was set by the <br /> client at 0.240 inch or less remaining thickness (ref. Table A). Nominal bottom plate <br /> thickness is 0.375 inch. <br /> Areas of restricted access to MFL inspection coverage included: near the shell-to-bottom <br /> weld, plate-to-plate lap welds and the fixed roof support column. <br /> The bottom lap welds were inspected utilizing VT inspection method. Reference Section <br /> 2.0 for findings. <br /> The internal shell-to-bottom weld (2-in. by 2-in. angle is utilized at.the shell-to-bottom <br /> joint to attach the shell to the bottom plates) was inspected utilizing VT inspection <br /> method. Reference Section 2.0 for findings. <br /> Bottom plate UT data was collected utilizing random readings. Five (5) readings per <br /> bottom plate were taken (ref. Table B). <br /> r <br /> 5.4 SHELL INSPECTION <br /> The internal 1 external shell welds were inspected utilizing VT inspection method (limited <br /> due to poor cleanliness). There were no recordable indications. <br /> The tank shell plate UT data was collected utilizing random readings. Ten (10) readings <br /> were taken per course along four(4) vertical drops, evenly spaced, around the shell and <br /> up the stairway(ref. Table C). <br /> APIRPTNE.DOT REV 2 2628030418r.doc 91252008 10:09 AM <br />