That's the only way I have ever seen it done. With the right prep work it makes a seamless weld. The guy I saw doing it makes polypropylene tanks for electrolysis operations. It was either polypropylene or polyethylene. I forget. After the welds were made, he used what looked like a hand held high voltage emitter. He ran the emitter on one inside of the weld, and a screwdriver (or anything conductive) on the outside. If the arc touched the screwdriver, there was a leak. Pretty neat.
I have recently bought a Lester hot air welder for building some PVC chemical tanks. I have played around with it quite a bit, and I'm starting to get better at welding with the simple pendulum technique. But now I'm interested in making polypropylene tanks for a higher temperature application. My local plastics fabricator told me PVC is the easiest plastic to work with. The materials I work with is mostly
Actually, I always found PVC kind of a bother to weld as it scorches so easily. PE and PP are a dream to weld in comparison so you should have little if no difficulty. A feed tip is highly recommended as you are able to press the rod into the seam. And though air has been used, nitrogen is still the preferred gas medium, especially for water tight welds.
PP (and PE) welds a bit slower than PVC but gives you more control as a result. If you use natural color PP (which I suspect you will), the rod will turn transparent when heated and look like clear silicone squeezed from a tube. But it will return to a translucent state when cooled.
Though you will have to adjust your technique when you get a feed tip, you can use the tip you have now and weld free hand. The feed tip increases you speed significantly and makes a much better looking weld.
PP has what I consider a citric smell when heated. One way to identify it.
Of course, the best way to understand all this is to play play play. Have fun.
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