Whether TIG welding, Mig Welding, Stick welding, or any other process, Restarts are part of the process. If you can make a decent restart, you are a lot less likely to have weld defects and a lot more likely to make a good looking weld.
What is the 3 second rule?
The 3 second rule says that it ...
Stainless Steel needs either backing or argon shielding to the back side when the back side melts. Argon shielding usually gives the best quality but Copper or Aluminum backing can also work fine depending on engineering or code requirements
TIG Welding Stainless Steel tubing with full penetration requires a purge in order to prevent severe oxidation on the inside.
There are some applications where purging the inside is an absolute must...especially in food service applications.
The manifold in the video is not required to be done ...