UTG ultrasonically measures the wall thickness of materials such as steel, plastic and also the metal thickness of a painted structure without having to remove the coating. It is ideal for measuring the effects of corrosion or erosion on tanks, pipes or any structure where access is limited to one side. Class Special/Renewal/Periodically survey. Annual/Intermediate Survey. Condition Assessment Program (CAP). Survey Condition Assessment Scheme (CAS) Survey. Transfer of Class (TOC) Survey. Owner’s Requirement Survey.