Lap-Weleded Bottom Joints
Lap-Weleded Bottom Joints
(OP)
We are replacing a section of bottom plate in a 40 foot dia. and 32 foot tall tank which has a lap joint. API 650 describes this type of lap joint in section 3.1.5.4-Lap-Welded Bottom Joints and shows a sketch of this type of lap in figure 3-3B. This is the lap joint where the shell sits on the bottom plate.
Is this lap formed in the fabrication shop? Or is it field bent and fitted. . The bottom plate is 1/4" thick.
If it is shop fabricated, wondering if there is a detail that shows the shop what needs to be done. Or must that detail be drawn up for the fabricator. I cannot find any exisiting tank drawings that show this detail, other than referring to the figure 3-3B in API 650.
Is this lap formed in the fabrication shop? Or is it field bent and fitted. . The bottom plate is 1/4" thick.
If it is shop fabricated, wondering if there is a detail that shows the shop what needs to be done. Or must that detail be drawn up for the fabricator. I cannot find any exisiting tank drawings that show this detail, other than referring to the figure 3-3B in API 650.





RE: Lap-Weleded Bottom Joints
Shop tanks have butt welded joints.
RE: Lap-Weleded Bottom Joints
RE: Lap-Weleded Bottom Joints
If you would like to make the breakdown then you could have them install the plates but before tacing the plates into place for welding , just have them tac the two together get all the laps right then slide the breakdown out from under the shell , make the breakdown , then slide it back under for final positioning , tacing , and welding.
The contractor if he is experianced in tanks should understand the process. although he will probably think you are crazy to ask him to make the breakdown.
Hope this helps.
RE: Lap-Weleded Bottom Joints