Agenda Item: / 650-778
Title: /

Sump Weld Detail

Date: / December 20, 2012
Handled by: / Charlie Race
Company: / Marathon Petroleum
Phone: / 313-583-1850
E-mail: /
Purpose: / Correct inconsistencies with weld detail in Figure 5-21 (Drawoff Sump)
Source: / David Rosenkrantz
Revision: / 2
Impact: / The business impact of this item is low.
Rationale: / The published figure detailing drawoff sump fabrication (Figure 5-21) has some inconsistencies.
In detail A2 the weld symbol specifies a 1/4" fillet and there is an arrow with a note that says "Full-fillet weld.” Since the minimum sump material is 5/16" thickness,the ¼” fillet cannot satisfy the full fillet weld requirement.
The fillet weld sizes in details B, C, and D are inconsistent (two are 1/4" and one is 5/16"). If the intent is that these welds are to be “full fillet” welds, the figure needs to be revised.
The weld symbol in Detail D does not detail the far side of the weld, only the near side.
Notes: / None.

Proposal: (Revision #1):

Note: The erection procedure shall be performed by one of the following methods or by an alternate design approved by a Storage Tank Engineer:

a)For sumps being placed in the foundation before bottom placement, the sump shall be placed in position with at least 100 mm (4 in.) of thoroughly compacted sand, or other suitable fill material, around the sump. The sump then shall be welded to the bottom.

b)For sumps being placed in the foundation after bottom placement, sufficient bottom plate shall be removed to allow for the sump to be placed in position with at least 100 mm (4 in.) of thoroughly compacted sand, or other suitable fill material, around the sump. The sump shall then be welded to the bottom.

Revisions made to drawing (Rev. 1) have been red lined above:

  1. In Detail a2 the figure was amended to show a full fillet weld with thickness “t” required on the arrow side of the joint. The arrow showing “Full-fillet weld” was removed since it is not an AWS symbol.
  2. In Detail b the figure was amended to show a 6 mm (¼”) fillet weld required on both the arrow side and far side of the joint.
  3. In Detail c the figure was amended to show a 6 mm (¼”)fillet weld required on both the arrow side and far side of the joint.
  4. In Detail d the figure was amended to show a full fillet weld with thickness “t” required on the far side of the joint.
  5. In Details a1,a3 and a4 AWS welding symbols were added in order to be consistent with the details provided in figures a2,b,c and d.
  6. The size of the circle at the end of the “See Details a1-a4” was increased in diameter in order to include the entire joint of interest.
  7. Removed the title “Details a1-a4” from the drawing.
  8. The words “(all are acceptable)” were removed from the drawing.
  9. Removed “150 mm”and “(6”) min” from drawing since the dimension is covered in another section of the code. This is the “J” dimension in column 7 of table 5-6a and 5-6b.
  10. The dotted line internal pipe was extended to the neck weld to delineate the between the nozzle and the internal piping.
  11. The size of the corner weld was increased; the current welds are barely visible.
  12. The end chime configuration was amended. The drawing which currently shows a cut line, would now be shown as square.
  13. Break lines were added in the bottom plate and in the pipe extension to indicate the figure is not intending to illustrate the weld spacing from the corner weld to sump. The sump is currently shown very close to the corner weld (approximately 6”).
  14. An AWS welding field weld symbol was added to the floor plate to sump flange welding symbol.

Revisions made to drawing (Rev. 2) have been blue lined above:

1.Detail a2
Changed the arrow side of the weld symbol from “t” to “Full Fillet” to reflect the original intent of drawing from 1980 edition.
Changed the lap orientation back to flange over bottom to allow users flexibility in design
Change the other side of the weld symbol from 1/4” to 5/16” to be consistent with the joint detail in “d”and “a3”

2.Detail a3
Changed the other side of the weld symbol from “t” to “Full Fillet” to be consistent with joint detail “a2”and detail d”
Change the arrow side of the weld symbol from 1/4” to 5/16” to be consistent with the joint detail in “d” and “a2”

3.Detail a4
Changed the lap orientation back to flange over bottom to allow users flexibility in design

4.Detail d
Changed the other side of the weld symbol from “t” to “Full Fillet” to be consistent with the joint detail in “a2” and “a3”