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61412010 t Bottom Patching (Critical Zone) 1. There is one(1)area of lamination near the critical zone of the bottom plates.This area shall be repaired by a tombstone shaped patch that will extend into the critical zone to the shell.This area is located In bottom plate#2;which is marked on the bottom with paint and is shown on the floor plate layout drawing.The pit depth is 0.145"and the remaining bottom thickness is 0.105". 2' Any bottom coaling in the repair areas shall be completely removed prior to weld preparation and welding. 3. • • •• Existing welds to be covered by a new patch plate shall be visually Inspected(VT)by a BP representative. 4. The existing shell4o-bottom comerweld shall be inspected for a distarhce equal to the edge of the patch plate ]16.on each side of the patch plate. 5. • '• The existing shell-to-bottom comervreld shall be Visually inspected(VT)by a BP representative. 6. • 1011=* The existing shell-to-bottom comerweld to be welded to the patch plate plus 6"on each side shall be Magnetic Particle examined(MT)by NDE contractor and witnessed by a BP representative. 7. The perimeter weld area,within the Critical Zone,shall be Ultrasonic examined(UT)prior to welding to confirm that the minimum bottom plate thickness shall be at least 0.100 inch. 6. • • '• The perimeter weld area shall be Ultrasonic examined(UT)by NDE contractor and witnessed by a BP representative. 9. The repair shall consist of welding 114"thick A-36 Modified patch plates war the damaged area. The sides of the tombstone patch plate shall intersect the shell-to-botlom comerweld at approximately 90 degrees.The edge of the patch plate against the shell shall match the radius of the tank.The length of the edge of the patch plate:against the shell shall not exceed 24". The patch plate installation shall be in accordance with API-653 Section 9.10 and Figure 9.9 for size,spacing from lap welds,and spacing from other patch plates. Patch plate shall be minimum 16'x 20"(with rounded comers)and shall overlap marked damage area by a minimum of 2'at any location. a. ffalllllls •• The correct position of the patch plate shall be verified ay a BP representative. b. The perimeter welds to the bottom plate,shall be two-Pass,minimum, 114'full fillet weld utilWng E7016 electrodes.The completed welds shall be cleaned for Inspection. C. • r :• The root pass welds shall be visually Inspected(VT)by a SP representative. d. fm• r • The root pass welds shall be Dye Penetrant examined(PT)or Magnetic Particle examinedMT)by NDE contractor and Witnessed by a BP representative. e. • r • Completed welds shall be visually inspected(VT)by a BP representative. I. • • Completed welds shall be Magnetic Particle examined(MT)by NDE conbactar and witnessed by a BP representative. g. All repair welds shall be tested using a vacuum box and a soap solution at a minimum negative pressure of 3 psi and a minimum holding time of 5 seconds. A right angle vacuum box shah be used to test the comerweld. IT. • r '• All welds shall be Vacuum Box tested(VB)by the repair contractor and witnessed by a BP representative. BOTTOM REDUCTION TABLE Nominal(interior]plate thickness: 0.250 Inch Nominal sketch plate thickness: 0.250 inch Southwest SW reference comer unless otherwise indicated. US=UNDDE IND=INDICATIONS LW -L WELD MD=raECHANICALDANWGE INT=INTERNAERSIL C2=CRmCALZONE CW.CORNER WELD NE=NDRTHFAS REFERENCE CORNER NOi D DEPTH THICKNESS LOCATION LOCATION �4 IND) NE Cz 1.1�1 CIE ron Slan OR 18x20" 2 0.105 0.16 8119 tem X Tomb•t•ro Patch • • • • Package • 1 • 1