by Adam
(Omaha,NE)
I worked on Heavy equipment and spent just as much time cutting as I did welding. Most of the material we were working with was 1/2" and larger.
I found on heavy material Propylene was the way to go. However it seemed like on material smaller than 1/2" I would still use acetylene. Although I think if I did not have a choice propylene would have worked just fine.
I will say this, If you are the one buying the gas, a propylene cylinder will outlast an acetylene cylinder about 3 to 1 so financially it makes sense.