Oil Refinery vessel internal Surface preparation for inspection best practice?

[turnaroundeng]

Hi,

I would like to know the best practices for the preparation of internal surfaces of oil refinery equipment (vessel/tower/reactor shells) for visual inspection?

currently we use HP washing (10,000 psi) but the inspection dept always complain and demand 2nd or 3rd attempts which results in significant delays.
We have also tried grit blasting (SSPC-SP6 and even SP10) but it is also a lengthy process (including clean up of spent grit) and dust generation is always an issue.

Thanks.