Advice Please

[Aireys]

Retaining nuts on low carbon steel Truck Body’s are to be welded inside the chassis sub frame.
The Truck body’s are to be made in batches of 2000 with 90 retaining nuts on each body.

Can someone state a suitable welding process for this application and the reasons for selecting this process?
Can you please explain how energy for welding is generated, and describe how the weld pool is protected from atmospheric contamination.

Many thanks
Stuart

[Sberry]

Was there a link to load with this? I doubt its a conventional weld, prolly resistance with special machine, there really isnt a weld pool.