https://www.youtube.com/watch?v=z0_hKcPtu-I
This industry video from Korean steelsmiths Dai Han Anchor shows workers forging and testing the largest anchor chains in the world. A fascinating mix of forge technology and cutting-edge quality control awaits.
Each link is subjected to checks for internal and external flaws, then subjected to punishing load tests. They have to be strong enough to moor an oil tanker or cruise ship safely.
They developed their own 12-step process which includes flash butt welding and stud inserting. In B4 obligatory Simpsons ref:
• DAI HAN ANCHOR CHAIN MFG.CO., LTD (YouTube / DHAC)