Theinspector's responsibilities, as defined in API 936, include visual and mechanical inspection of installed linings.Hammer testingis one such non-destructive method used to detect delamination, voids, and rebound areas by listening for variations in sound. It is a practical method during and after installation.
Other tasks like providing compliance documentation or water testing are typically done by the contractor or laboratory personnel.
Reference:
API Std 936, Section 7.1 - "Inspectors shall perform hammer testing as part of surface inspection to detect voids and delamination."