If I understand your question correctly the criteria remain unchanged from the visual acceptance criteria.

The dye penetrant is just a tool that can help detect the ends of tight cracks or if two close indications are actually linked.

It takes some experience to read red or flourescent dye indications so as not to measure penetrant bleed onto the developer that extends beyond the actual discontinuity/defect.

Excellent topic in the metallogical section...well done!

Let me take a wild guess, is the criteria listed in said code? if so, you have to buy it!

3.2

To be use Table 6.1 of AWS D1.1 same as visual inspection.

Good Luck...