Thickness checks for Mechanical integrity with PSM

[StoneCold]

I have a question about how others are doing thickness checks for mechanical integrity with PSM. I am in colorado. We are having a hard time finding a local contractor that can do thickness checks (ultrasonic) on glass lined equipment. In the past we have always used a third party to validate the thickenss checks. However I wonder if we really need to do that and we could do the measurements ourselves if we documented it well.
Opinions on that?
Anyone with experience on glass lined equipment doing it themselves?

Thanks
StoneCold

 

[skearse]

Are these for reactors (pressure vessels) or storage tanks? Do you also do spark testing on the glass itself? Do your internal people have any NDT dertifications? Regardless, especially since you are in a "compliance" situation, I would probably recommend staying with a 3rd party verification-just an added layer of comfort.