Some points to consider:

1.    You are right about the requirement for VT during all phases (before, during and after) of the welding process. This will certainly satisfy minimum code requirements and provide greater safety. D1.1 Section 6.9 requires VT of all welds. If Chpater 17 of the NBC does not have a provision which allows for a lower frequency, than I presume that is what you'll have to go with.

2.    According to D1.1 Sections 2.20, 5.26.1.4, and 6.10, MT and PT will not be required, except for determining the extent of cracks in welds.

3.    If there is welding of rebar to structural steel involved, welders and WPSs will have to be qualified to both D1.1 and D1.4. See also PCI MNL Article 2.3.1

4.    In addition to NBC Chapter 17 which references AWS D1.1, useful references are D1.1 Section 6 Part A and Table 6.1, PCI MNL 116 Article 2.3 and IBC Table 1704.3.  The IBC does allow for periodic inspections of certain welds while D1.1 Sections 6.9 and C6.9 do not. I included the IBC Table because it clearly elucidates the different items which require inspection; something you can modify to suit your needs and still meet BOCA requirements.

Thanks for your insight...it is very helpful.

I read that RI's building commission adopted the 2003 IBC last July. When will building departments in the state start requiring that building structures be designed according to IBC provisions?