Lap Welded for Bottom and Annular Plates
Lap Welded for Bottom and Annular Plates
(OP)
Dear All,
As per API 650 ed 12 2016, para 5.1.3.5 Lap-welded joints, as tack-welded, shall be lapped as follows: - Single-welded joints shall be lapped at least five times the nominal thickness of the thinner plate joined, or 25 mm (1 in.), whichever is smaller.
From the statement above, is it right if we lap:
1. bottom plate to bottom plate by minimum 25 mm?
2. bottom plate to annular bottom plate by minimum 25 mm?
Help me with this, as I could not find a specific statement that rules the lap between bottom to bottom plate or bottom to annular plate.
Thanks for the help!!!
As per API 650 ed 12 2016, para 5.1.3.5 Lap-welded joints, as tack-welded, shall be lapped as follows: - Single-welded joints shall be lapped at least five times the nominal thickness of the thinner plate joined, or 25 mm (1 in.), whichever is smaller.
From the statement above, is it right if we lap:
1. bottom plate to bottom plate by minimum 25 mm?
2. bottom plate to annular bottom plate by minimum 25 mm?
Help me with this, as I could not find a specific statement that rules the lap between bottom to bottom plate or bottom to annular plate.
Thanks for the help!!!





RE: Lap Welded for Bottom and Annular Plates
RE: Lap Welded for Bottom and Annular Plates
However, in many storage tanks drawing I have seen, the lap between bottom to annular is normally higher than 25 mm... I understand the minimum lap is 25 mm, therefore lap higher than 25 mm is not a problem.
But what becomes my concern is why the designer would lap the bottom to annular with higher lap in which it will make the use of material is more than if we use 25 mm lap welded joint.
Is there any calculation for to determine the lap between bottom to annular plate?
RE: Lap Welded for Bottom and Annular Plates
RE: Lap Welded for Bottom and Annular Plates
RE: Lap Welded for Bottom and Annular Plates
What about the code/standard? Is there any reference covers about this (AWS, ASME)?
I think I need the code/standard to argue to the client as I have limited experience about this.
RE: Lap Welded for Bottom and Annular Plates
RE: Lap Welded for Bottom and Annular Plates
The European tank standard 'EN 14015:2004' does actually specify a minimum lap of 60mm for the bottom plate to annular. Laps between 2 bottom plates remian the same as API 650 i.e. 5 x the plate thickness.
However as IFRs stated if your tank is in accordance with API 650 then a lap of 1" ( 25mm ) should suffice as it complies with the minimum requirement of that standard.
RE: Lap Welded for Bottom and Annular Plates
Well, I guess I should move on, thanks IFRs!
sajk14,
Thanks for the reference, that really helps!!!