What you have described is only used on printed circuit boards, to melt existing soft solder in an attempt to fix any loose connections, maybe even some open circuits if you are lucky. Its not welding, which fuses the 2 metals together by heating them so much that they melt and mix together. Nor is it soldering, where a binding alloy melts between the 2 metals, filling any gaps and firmly holds them together; It is just soldering with an oven, and has no tactile strength whatsoever, which of course it does not need, as it's purpose is to merely coat conductors to create an electrical circuit. And you certainly cannot do any welding, braising or soldering of things with water/fluids in or around them.
@Fumferknuckle
Different metals require different techniques to join them together, and it gets a lot more complicated if you have 2 different ones. Copper, brass, steel, and stainless steel can be braised together, though you certainly need to have some experience - you might be able to clump it into a mess that holds on your first try if you are just joining copper to copper, but anything else is out of the question. Attempting it and making a mess of it tends to make it impossible for anyone to fix afterwards, as due each metal having completely different melting points, and rates at which they disperse heat, it is very easy to melt one of the 2 completely, or carbonize and "dirty" the joints so much that no solder will ever stick. Then there is aluminium and aluminium alloys - you cannot solder them at all, as they have very low melting points - too low to use a flame on. Alum needs to be balustraded, a type of welding, and makes it very difficult to bond to anything other than itself.
Coming back to the topic - joining "heating pipes" - it all depends on the metals involved. Some heat exchangers, like those you find in air conditioning equipment, are made with copper tubes, as they need to be able to handle rapid temperature changes without cracking/fracturing due to expansion & stress, and as such can be repaired and modified relatively easily if the aluminium fins in the area are cut away. You also find some heat sinks with copper tubes in them like this too. Then there are other heat exchangers that have linear climbs/declines, and don't have to handle the temp swings. Like a radiator in a car, or the heat exchanger used for water cooling a CPU.Inclined to crack as much as they expand, its not something to worry about under normal operating conditions,and thus are generally just made out of aluminium or alloys, which is much cheaper than copper. So bottom line is if its orange/brown you can do it, but if silver/black it should be left alone.
But saying that, there is nothing stopping you from fitting flexible lines, without welding - using clamps, threaded fittings, or glues. Im in the middle of water cooling my PS4, so actually had to do this myself when I broke a line trying to squeeze everything in. Ended up having to glue new fittings into the pump housing, and fit new lines between it and the radiator, and am prob just going to hose clamp to the radiator stubs. You can get around a lot of mech welding with fittings, and unless it is an absolute necessity for either thermals or strength, that they be directly connected, often times it can be better not to. it makes things a lot more manageable for any maintenance and repairs, if you can simply disconnect things.
Spoiler: You can NOT infact cleanly hide the fan and/or rad in the case of a PS4 pro, without gutting the power supply. No matter how much room there seemed to be, it was never enough, no matter how i shuffled things. 5mm to short, or 10mm too tight, or 5mm too long, always 5-10mm off (<1/4-3/8 inch) .Always something in the way. Considering sripping the supply, just out of spite, and just make it into an external xformer, or maybe even modify an xbox supply. Piece of shit better still work at the end. LOL
