Fact 1, I have 50 years of experience welding & cutting metal.
Fact 2, When you cut steel with either O/P or O/A the actual fuel involved in the cutting is the steel! Ever heard the term Burning Steel?
I think Esab might still have a good description of how O/A and O/P cut on their website, but I haven't had occasion to look lately.
BTW, In Laser cutting, if the laser also uses oxygen the steel is the true cutting fuel.
Your contention propane offers more BTU value is also erroneous as stated. Propane may offer more BTUs per dollar spent, but that is a difficult statement to forward given the differential in gas prices by geography and consumer. Hell a gallon of propane can currently run between 79ยข and $4.00 depending on volume and location alone.
Your suggestion buying oxygen is somehow preferable to buying acetylene indicates to me you are not conversant with the welding world. I've watched a lot of propane happy people advocating using propane over acetylene over the last 10 years on the web, and frankly most of them fit right in with the every 9 month thread where Goober discovers Petrogen gasoline torches. BTW, I bought oxygen in 122cf cylinders and I buy oxygen in Dewers. I bought based on my use, not a misguided dream of economy.
No cylinder is a torpedo. They are merely pressure vessels to be treated with appropriate respect.
Both Acetylene and Propane cylinders contain overpressure and overtemprature safetys, and in fact an Acetylene bottle in a fire blows off and roostertails far less violently than a propane cylinder in the same fire.
Burning steel gets pretty damn sophisticated once you get beyond chopping metal down to 3 feet for scrap. Suggesting that anyone who can barely chop steel with an O/A torch can transition to O/P and get the same result indicates lack of experience. In 50 years I've run across maybe 5 men who can cut as well with propane as they can with O/A. In machine cutting situations such as tractors & guided pantographs or X-Y tables and particularly on cutters where the steel lays in water damn comparable cuts can be made. Handheld free cutting Propane leaves you wanting and grinding as well as chopping dross off the back of the cut.
Propane is superior if you're cutting rust encrusted steel and also beneficial cutting sandwiched steel when the torch operator knows what he's doing.
As to "Why do you think propane won't work on steel?"; Please define what you mean by "work on". As I have previously stated the fuel gas to the torch becomes irrelevant once the cut has been established. The steel becomes the fuel that sustains the cut. Give me 15 minutes to practice up and I'll cut steel with a welding tip by turning the fuel off.
You apparently lack acquaintance with the cutting of thick steel. Should you have the chance to observe a cutter doing that work you'll notice the skilled man will use a cold chisel to feather the steel and get the cut established. That feather saves many cubic feet of fuel gas.
The reality remains a Propane torch burns more cubic feet of fuel per time than a similar sized O/A torch. Oxygen to fuel ratio is pretty much unchangeable due to those inconvenient laws of physics politicians seem to think they can repeal. More cf of fuel automatically mandates more cf of oxygen.
