Distance between 2 longitudinal welds of different panels

By joao56777 Date 03-17-2016 11:14

I have a doubt that i would like to share with the forum,

I have 2 panels, with 3 longitudinal welds. After the longitudinal welds, this two panels will be welded with a transverslsal weld.
Because the width of every plate is not the same, when we make the transversal weld, the longitudinal welds dont fit in the same line. They will be disalligned with each other.

This is any problem?

Attachment: Untitled.jpg (30k)

By Don56

Date 03-17-2016 20:28

Are you welding to any construction/design code? Often it is mandated that the welds be offset by several inches.

By joao56777 Date 03-17-2016 22:48

This for welds of a double bottom of a ship. normally, the weld beads will be offset, like a pressure vessel construction. But in this type of construction i didnt find nothing... the "good practices", i think this need to be disaligned and not alligned

By Don56

Date 03-18-2016 19:25

If you do not have a design code for guidance you should use good engineering practices.

By welderbrent (*****)

Date 03-19-2016 00:16

joao,

WELCOME TO THE AWS WELDING FORUM!!

A ship? Now, last I looked, AWS has limited codes for ship welding. Those they do have are the D3 series: Steel Hull Welding, Underwater Welding, Aluminum Hull Welding, and Welding Through Paint Primers.

But, what you are asking is an engineering stress calculation query. This will not be covered in much detail in any welding codes.

It will most definitely depend upon stresses and how they are trying to distribute them. Some will be handled better in line while others will want to be offset. In all construction it is the same and they don't pay us to GUESS what we THINK may work best or to tell everyone else some old wives tale we heard about what needs to be done. We are paid to do the job as specified in the Contract Documents according to the approved erection and shop drawings. He may be wrong, but the engineer ALWAYS knows best.

He Is In Control, Have a Great Day, Brent

By 803056

Date 03-21-2016 01:52

Standard practice is to weld the longitudinals (per your sketch) first, followed by the transverse seam.

Were you to weld the transverse seam first and then the longitudinal seams, the residual stress in the transverse seams could tear (crack) the transverse seams.

In many cases, it is preferable to have the joints offset because the mechanical properties of the plate are often superior to the properties of the weld due to the course grain of the weld (compared to the fine grain of the plate). In many cases the plate is subject to bidirectional rolling to enhance the mechanical properties in the X and Y directions and to reduce the anisotropic properties that result when the plate is rolled in one direction.

Al