Title: /
Sump Installation
Date: / November 15, 2011Handled by: / Charlie Race
Company: / Marathon Petroleum
Phone: / 313-583-1850
E-mail: /
Purpose: / Add guidance on sump installation
Source: / David Wang
Revision: / 2
Impact: / The business impact of this item is medium.
Rationale: / The sump installation requirements are listed in API 650 Figure 5-21 note (a), which states that a hole shall be cut in the bottom plate or a sump shall be placed in the foundation before bottom placement. Placing sumps after the bottom is laid is a problem that will cause bottom and sump failure. Compaction cannot be done after dropping the sump in the hole. A hole can never be dug so perfectly that when the sump is dropped in the hole it gets full soil contact as required. In most cases there is about 3" of space. Eventually the ground will slough off and create a large area of no bottom contact with the soil.
Notes: / None.
Proposal: (for publication):
(Delete the strikethrough text note below)
Note: The erection procedure shall include the following steps: (a) a hole shall be cut in the bottom plate or a sump shall be placed in the foundation before bottom placement; (b) a neat excavation shall be made to conform to the shape of the drawoff sump, the sump shall be put in place, and the foundation shall be compacted around the sump after placement; and (c) the sump shall be welded to the bottom.
Replace above note with following text (revision 1). Revision 2 changes are highlighted in red.
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 replacement placement, the sump shall be placed in the foundation with at least 100 mm (4 in.) of sand thoroughly compacted around the sump. The sump then shall be welded to the bottom.
b) For sumps being placed in existing bottoms the foundation after bottom placement, sufficient bottom plate shall be removed to allow for the sump to be placed in the foundation with at least 100 mm (4 in.) of sand thoroughly compacted around the sump. The sump shall then be welded to the bottom.
Figure 5-21 – Drawoff Sump (See Table 5-16a and 5-16b)
Revisions made to drawing in revision 1 are highlighted in yellow:
1. Floor plate is now shown shingled above the sump. Current drawing shows sump shingled above floor plate.
2. Drawing is now shown with 100mm (4in) Sand Cushion around the existing sump.
3. References (2 spots) to details a1” a4 were changed. From a1” a4 to a1-a4
Revisions made to drawing in revision 2 are highlighted in blue:
4. AWS welding symbol changed to reflect that the bottom to sump attachment is to be a full-fillet weld versus a 5/16” fillet weld.
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