CVN is required when the design authority, i.e., Engineer, specifies CVN has to be addressed. The Engineer also has to specify the test temperature and the required "absorbed energy" required to pass the test.
Best regards - Al
Wouter,
Both 1) and 2) are correct. The SEV's, as described in Table 4.6, become applicable whenever your application requires that welding procedure qualification includes impact testing. In the case of your 2) below, the minimum action required is that your weld an additional coupon(s) and do CVN testing in accordance with AWS D1.1, Section 4, Part D - "Requirements for CVN Testing" as well as any additional/alternate requirements from the contract documents, such as test temperature, total number of test specimens, etc.
When doing this additional CVN test coupon, care must be taken to insure that all welding is done within the variables of the original PQR/WPS.
Hope this helps.