Inspector is measuring thickness of the pipe material from near to weld with a portable ultrasonic wall thickness measurement gauge. It is a method of performing non destructive measurement (gauging). Stock Photo
Portable Ultrasonic Pipe Thickness Gauge, Through Paint | ATO.com
Simple Ways to Find Wall Thickness of a Pipe: 9 Steps
Digital caliper for tube wall thickness measurement
File:Tube thickness measured by a Vernier caliper.jpg - Wikimedia Commons
Measuring the Wall Thickness of Small-Diameter Metal and Plastic Tubing
MiniTest 7200/7400 FH: A high-end device for wall thickness measurement | UK Dyne Testing