There are several Oxy/acetylene rigs in that shop. I bet the big boiler/heater setup vents out through that brick wall. Coolest rig is that auto/roller welding unit just in front of the guy on the right. The deal there is the torch is on rollers that they move along the joint of the steel plates aligned underneath it. Makes it much easier to weld a straight long joint between two plates. Not sure if that would have been manually moved or driven by an electric motor (with some kind of speed control). Anyway, that's doing it old school and a pro could make a joint stronger than the base metal.

First, that looks like a hell on earth place to work. Second, is that some sort of furnace or heater on the right? It looks to have a door for loading in coal or some sort of fuel. It has ducts coming from it ending in the work space but it doesn't seem to be the normal combustion chamber / heat exchanger arrangement. It doesn't have a chimney, it looks like all the combustion byproducts are vented into the work area. Not to mention all the tanks of explosive gases near by, some right next to the "heater".

During World War II Mare Island Naval Shipyard turned out scores of ships and submarines, assembling new destroyer escorts with prefabricated sections brought in from as far away as Colorado. Warships damaged in battle were also repaired and refitted in the base's drydocks. By the end of the war, Mare Island had produced 17 submarines, four submarine tenders, 31 destroyer escorts, 33 small craft and more than 300 landing craft.