Dimensions Flashcards
Linings – typically anchor profile of steel surface required for the installation of a tank bottom lining
1.5 - 4.0 mils
Welds – maximum undercut of a vertical weld and nozzle weld
1/64”
Welds – maximum undercut of a horizontal weld
1/32”
Welds – maximum diameter of a surface porosity cluster
3/32”
Weld qualification – max allowed discontinuity in a bend test
1/8”
Nameplates – minimum size of nameplate letters
5/32”
Bottoms – minimum external projection of bottom plate on an existing tank (from toe of shell-to-bottom FW)
3/8”
Reconstruction – max amount of peaking allowed in vert welds
1/2”
Shell Calcs - when calculating tmin for shell LTA, minimum distance away from a weld where “E” is always 1.0
> 1” or 2t
Shell patch - minimum overlap of shell lap-patch used to cover a hole (edge of hole to edge of patch)
1”
NDE - When performing a PT examination, minimum distance to clean beyond the area to be examined
1”
NDE - When performing a MT examination, minimum distance to clean beyond the area to be examined
1”
Reconstruction - Maximum amount of banding allowed in a horizontal welds
1”
Bottoms - Minimum overlap required for single-welded lap joints
1”
Bottoms - Minimum external projection of bottom plate on a new tank
2”
Vacuum Box - Minimum overlap of previously test surfaces when using a vacuum box
2”
Bottom Patch - Minimum overlap of bottom lap-patch used to cover corroded area (edge of corrosion to edge of patch)
2”
Bottom Patch - Minimum distance bottom lap-patch fillet weld to the nearest existing bottom weld
2”
Shell Patch - Minimum radius of a shell lap-patch
2”
Reconstruction - If reusing bottom plates, min distance to cut from existing bottom welds (if plates are not deseamed)
2”
Reconstruction - If reusing roof plates, min distance to cut from existing roof welds (if plates are not deseamed)
2”
Shell Pitting - Maximum allowed vertical length of pits on a tank shell
2” in 8” line
Bottom Pitting - Maximum allowed length of pits in the critical zone that can be repaired by weld-buildup
2” in 8” arc
Bottoms - Radial length of critical zone measured from shell
3”
Bottoms – Suggested pad thickness
3-4”
Welds - Min distance between clusters of surface porosity
4”
Shell Patch - Minimum dimension of a shell lap-patch
4”
Shell Patch - Minimum radius of a shell flush-patch
6”
Shell Calcs – When calculating tmin for shell LTA, minimum distance away from a rivet where “E” is always 1.0
6”
Bottom Patch - Minimum size of bottom lap-patch that does NOT cross a bottom seam
6”
Bottom Patch - Minimum distance between a bottom lap-patch and the shell for patches that do NOT extend to the shell
6”
Reconstruction - If reusing shell plates, min distance to cut from existing shell welds (if plates are not deseamed)
6”
RT - Minimum diagnostic length of a RT for vertical or horizontal welds
6”
Weld Qualification - Minimum length of RT when qualifying a welder with RT using a coupon or 1st production weld
6”
Weld Qualification - Minimum length of RT when qualifying a welding operator with RT of a test coupon
6”
Shell Patch – Minimum distance to overlap a shell weld when using a lap-patch
6”
Corrosion – Area to dig when checking for soil-to-air corrosion
6-12”
NDE – Distance of eye-to-part to count as a Visual Exam
6-24”
Vacuum Box - Typical size of a vacuum box
6” x 30”
Shell Patch - Minimum dimension of a shell flush-patch
12”
Bottoms - Minimum dimension that a 3-lap joint can be from: other 3-laps, the shell, or annular plate joints
12”
Bottom Patch - Minimum dimension of bottom lap-patch that crosses a bottom seam
12”
Foundations - Suggested height above grade for new tank bottoms
12”
Shell Patch - When adding a shell flush-patch that extends to a horizontal shell weld, minimum distance to cut the horizontal weld past the new vertical welds
12”
Shell Patch - Dimension of a shell flush-patch that is considered either a major repair or alteration
> 12”
Definition - Dimension of a shell vertical weld if repaired or replaced is considered a major repair or alteration
> 12”
Bottom Patch – Max width of bottom patch in the critical zone
24”
Bottoms - Minimum radial width of annular plate (distance between shell and nearest bottom fillet weld)
24”
NDE – Max distance of eye-to-part to count as a Visual Exam
24”
Hot Tap - Minimum height of liquid above new nozzle during the hot tap operation
36”
Weld Qualification - Minimum length of RT when qualifying a welding operator with RT of first production weld
36”
NDE - Length of sweep board used when checking for banding or peaking
36”
Welds - Maximum distance between welder ID stamps on a tank weld
36”
Shell Patch - Maximum size of shell lap-patch (vertical & horizontal dimensions)
48” x 72”
Settlement - Maximum distance between tank settlement survey points across the inside of the tank
10’
Roofs – Maximum shunt spacing on floating roof
10’
Settlement - Maximum distance between tank settlement survey points around the outside diameter of the tank
32’
NDE - Maximum distance between RT’s in horizontal welds when welding to existing shell plates
50’
CP – Typical tank size for Galvanic CP systems
Shell Calcs - Tank diameter when variable point design method should always be used to calc shell minimum thickness
> 200’
Shell – Minimum offset between vertical welds in adjacent courses
5t
Bottoms – Minimum size of bottom welds
Full Fillet
Definitions – length of Shell–to–bottom weld that if repaired is considered a major repair or alteration
> 0”
