There's lots of good information already up.
I can join metal sufficiently well for yard work, but have had the pleasure of watching some absolute master craftsmen in action on equipment that I've been the engineer in charge of.
Spent an hour watching one TIG expert manufacture new blade tip tenons on a steam turbine (english and german blade fitters reckon his work was best in world, including their factory technicians) in 410 stainless, and weld 410 stainless coverband back together with inconel...at the end of the hour, I was fatigued, and he was working 12 hour shifts...gets phonecalls from all over the country.
Another boiler job, I watch two guys welding pressure tube, one on the torch, one feeding wire. One of them I've seen put the root run in on the back of a tube, while he watched the action through a hole he burned through the front of the weld prep...his welds pass radiography 95% of the time...neither of them have any formal qualifications, the turbine guy does.
A friend's husband makes a living working at a workshop that
Also seen qualified guys fail at a hand rail test.
To give an idea of the demand, the welding codes in Oz allow people with no qualifications whatsoever weld on pressure equipment and structures, as long as they pass the tests, keep doing that work at least once every 3 months, and work under a certificated supervisor...must also "qualify" by sample weld subject to destructive testing on each weld procedure (combination of materials, thicknesses, positions, and arrangements).
It's a fascinating field.
But you need to decide what you want to do.
Boilermaking (plate work and fabrication of big steel stuff);
Precious welding (pressure welding on certified vessels);
Factory/production (combinations of those above);
Hardfacing, for construction and mining equipment;
Field specialty work (like power stations);
Newer fields like plastic.
While ever there is a coal fired power station, there will be a need for guys who can be on site in 12 hours, work 10 days straight 12 hours per day, while hanging upside down on a swinging stage 50 feet up in the air.
While our waterways become depleted, we need more water treatment equipment, and people who can stick high end stainless together without creating rust spots.
With a massively aging fleet of power stations, we need people who can cut out and replace welds in 30" pipes, 4" think in mongrel materials like 1/2Cr, 1/2Mo, 1/4V, where the welds age at twice the rate as the pipe.
Keep something else up your sleeve 'though, as many of the precious welded that I know never retire as welders. Their eyes go, they lose the mobility to crawl 30' through 2' crawl spaces across 6" spaced 2" tubes
