Tank Bottom Bevel

[nabeel3]

Dear All

Is it required that for an 8 mm new bottom plate replacement over existing plate shall have full penetration weld to the shell plate. I mean is a bevel required in the shell plate . All bottom plate to be replaced. Plate is A36. API code .

 

[HTURKAK]

Refer to API 650 5.1.5.7 Shell-to-Bottom Fillet Welds and Figure 5-3—Typical Roof and Bottom Joints.
What was type of the Shell-to-Bottom Weld of old base plate ?

 

[nabeel3]

Drawings are not available in the plant . The tank is constructed in the mid 80's . Now , bottom shell thickness is around 9 mm. i was thinking is it required to do bevel of the shell plate (9 mm). Also my understanding is that the new bottom plate shall also extend 50 mm outside of shell ,one of my colleague is saying for the new plate no extension is required. I am confused

 

[Dhurjati Sen]

Refer API 653 bottom plate replacement and NOT API 650.
Once you go through, hopefully, you will not have any doubt.

 

[nabeel3]

Dhurjati Sen

Oh, sure . Confusion came because of the word Bottom plate replacement. We are adding a new plate over existing bottom.

 

[HTURKAK]

..,one of my colleague is saying for the new plate no extension is required. I am confused

Your colleague is not right . The new bottom shall extend outside of shell.

Now , bottom shell thickness is around 9 mm. i was thinking is it required to do bevel of the shell plate (9 mm).

Refer yo 5.1.5.7 Shell-to-Bottom Fillet Welds.
(For bottom and annular plates with a nominal thickness 13 mm (1/2 in.), and less, the attachment between the
bottom edge of the lowest course shell plate and the bottom plate shall be a continuous fillet weld laid on each
side of the shell plate.)

 

[nabeel3]

Thank You all for your response