B31.3 Fillet Weld Examination

[svi]

Why does ASME B31.3 Table 341.3.2 call for RT examination of fillet welds. How should I read this. I understand that RT on fillet is difficult and others methods are to be used.
I found the following reference in here,

http://www.eng-tips.com/viewthread.cfm?qid=225832

but not what I am looking for.

 

[david339933]

It is not specifically saying RT must be done, the check mark states that RT is the "method generally used for evaluating this kind of weld imperfection", (note (c)). Many other things such as weld type, joint geometry, location etc., will determine the type of NDE required.