Plumbing bladder - GIF

[desbromilow]

a bit of a general question if you don't mind...
the heater gadget I'm seeing in these types of videos, is it just for softening the PVC to aid forming the spigot/ socket, or does the heater melt the PVC enough to form a thermoplastic weld joint?
In my part of Australia, I typically see solvent based joints when dealing with PV plumbing pipes (up to PN18), and thermoplastic welded joints in larger diameter stuff (100mm and over in black (or other colours) Pipe)

I prefer PVC for DWV (Drain Waste Vent), and brazed copper for supply, but have used PN12 and PN18 PVC pressure pipe for the retic and other gardening outlets in the back yard. The solvent glues sold for the PVC pipe come in a blue "non-pressure" glue, and a green "pressure" glue. - there is also a clear non pressure version for joints which are visible