API 650 Flush type clean-out Reinforcing Bottom Plate weld to regular bottom plates

Question

API 650 Flush type clean-out Reinforcing Bottom Plate weld to regular bottom plates

Legoman92 (Structural)

(OP)

12 May 22 00:40

Hi all,

Little bit of confusion from Figure 5.12 about what is allowed in regards to welding reinforcing bottom plate and the other bottom plates. Section D shows a bevelled Reinforcing bottom plate with full pen butt weld with 32mm overlap (which appears to be around the shell interface, but shows a fillet weld in section A. Do I need to provide a bevelled full penetration weld around the whole reinforcing plate/bottom plate connection? Is it acceptable to just do a regular full penetration weld between the two (see proposed detail which is taken from the flush nozzle connection)? Seems a bit ambiguous to me. See attached for images

JStephen (Mechanical) · Answer 1 · 2022-05-12 03:55:51

The notches shown in Section D-D are only at the ends of the plate, and are so the surface is flat under the shell. Along the backside of the plate, the bottom is lapped as in Section A-A.

Legoman92 (Structural) · Answer 2 · 2022-05-12 06:52:41

Thanks so much JStephen. I had a contractor complain that the fabrication was "impractical" to profile the reinforcement plate in lieu of just doing something similar to the detail circled in blue above. I didn't really have an answer other than "the code says so". I'd be interested to know why the Section D weld detail is chosen.

Milad -H-CH (Mechanical) · Answer 3 · 2022-05-15 08:31:25

According to API 650 table 5.10 a the thickness of bottom reinforcing plate for flush-type clean out is thicker than tank annular plate and in accordance shell plate shall be welded to smooth sheet surface therefore detail D-D shall be used only welding for bottom reinforcing plate for flush-type clean out (special annular plate) to tank annular plate.
detail A-A shall be used welding for bottom reinforcing plate for flush-type clean out (special annular plate) weld to bottom plate.

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API 650 Flush type clean-out Reinforcing Bottom Plate weld to regular bottom plates