Hi Jayendra, as far as I know, API 6A and API 20D do not require something specific. they refere to the common non destructive norms such as ASTM E 709 but may require a fluorescent inspection method or having spcific accaptance criteria. If we go in detail, the Pie Gauge would not be enough to validate. Off course you need a seperate validation of your fluid or suspension, magnitization, lightning (lx), etc. however, in the end the System is validated with the pie gauge having all elements verified on its own. Pie gauge allown would not enough.
W.r.t. penetrant testing, please find attached reference block we use to validate the test with. When testing youre product, you do exact the same with the reference block. This have never doubt in an Audit.