Jouko,
The fact that welds, All welds, are subject to "NDE" has nothing what-so-ever with the minimum distance between welds.

And yes the proper term is NDE (Non-Destructive Examination) not NDT.


See the following website for an article (American Welding Society)with more details on NDE:
http://www.ndt.net/article/0698/hayes/hayes.htm