In the inspection, test, and maintenance procedure for a valve other than a post indicator or wall indicator valve under component replacement action requirements, what is the last step to be performed?

• A. Main drain test
• B. Final valve adjustment
• C. Pressure test of the line
• D. Visual inspection

Answer: (A)

The last step is the main drain test. After completing all other checks and adjustments, this test confirms the drainage path from the main line operates correctly and that the system can be depressurized and drained without leaks. It verifies the valve assembly and its connections will behave properly when the system is drained, which is essential before putting the system back into service. Earlier steps, like a visual inspection, line pressure test, and final valve adjustments, ensure nothing obvious is amiss and the system holds pressure; the main drain test then provides the final verification that drainage works as intended and there are no hidden leaks at the drain or along the main line.