API 510 Pressure Vessel Internal Inspection 1

[Kaplin]

API 510 says that an external inspection may be acceptable when size, configuration or lack of access makes vessel entry for internal inspection physically impossible.

This may be a silly question, but having never seen an internal inspection, how much access is required? Does someone physically have to fit inside? What testing is required for an internal inspection?

 

[Tankman650]

An internal inspection is generally a 100% visual inspection with additional UT thickness measurements and NDT of nozzles and seam welds as required.

Yes, you need access to 100% of the interior. This may require internal scaffolding.

UT thickness measurements are required to determine the corrosion-rate. Although these measurements may be taken externally, most process vessels are insulated and it is cost effective in many cases to obtain thickness measurements on the interior so that insulation may remain in place. Only sample areas of insulation are removed around nozzles and suspect areas to verify interior measurements and check for under insulation corrosion.

 

[Kaplin]

Thank-you for the reply Tankman - I'm generally interested in smaller 45-70 ft3 air receivers. Although they all contain man-holes, is there a specific dimension in which the vessel is considered too small to enter?

 

[Norphlet]

API 510 gives the judgment to authorized pressure vessel inspectors. API 510 says:

At the discretion of the authorized pressure vessel inspector, on-stream inspection may be substitued for internal inspection in the following situations:
a. When size, configuration, or lack of access make vessel entry for internal inspection physically impossible.
b. ------

Yes, authorized pressure vessel inspectors, maintenance persons, and related persons completely get inside of the vessels.

 

[RVTMan]

Are remote visual inspections (via video camera systems) acceptable in some instances?