4 KW generator set

[PITMIX]

No, an anaconda welds. It's professional equipment for refrigeration installations and it costs the skin of the buttocks.
What you need to look for is first and foremost why your fittings are breaking.

Normally copper does the trick. It is easy to work with welded or mechanically connected.
I did a Pantone assembly on a mini bike, the copper fittings broke because I hadn't taken care of the assembly. The engine vibrated the reactor. In addition the weight of the reactor was on the exhaust outlet. That's where it broke.
The best is still to make everything in very solid steel and arc welded. Secure everything correctly engine and reactor together, and arrange to fix the engine on a frame with silent blocks between the engine and the frame.
The connection of the reactor outlet to the admission you can do it with reinforced hose. Available in auto discount stores (Norauto, Autobac...).