Acet - Propane - Thoughts on gear

[woodlandfarms]

My Santa thread took a turn, and I would love to start a new one to get as much info as possible.

If I know squat about welding, I really know nothing about cutting, bending, melding steel. I have been around it, done it a few times, but none of it my own gear.

I have permission to get a used oxy set. I want to bend and cut, no brazing. I have read on many sites that Oxy Propane is a better way to go, Propane being cheaper, and a hotter cut, a bit harder tecnique to learn. Apparently scrappers use Oxy Propane more than Acet.

I saw the notes that buying used is high risk, low reward. As I know so little about what I am looking at, seems to me like an accident waiting to happen and maybe a new system would be better.

Plasma is out for the moment, not till next year.

So bring on your insight on all issues including used, brands, oxy v propane, and any other insights that might keep me from getting killed.

 

[Shield Arc]

I just switched over to propane last summer. I hadn't used it since the mid 1980s working on a joint venture project where the other contractor was the sponsor. In my opinion it cuts just a little slower, and takes just a few seconds longer to pre heat. But it does make for some nice cuts.
Here is a great video about cutting with propane.
A picture of a cut I made on 3/8-inch flatbar, and 1-inch plate.

Propane & Oxygen Torch Cutting Instructional Video - YouTube

 

[kcender]

I have used both and prefer acetylene as it has a more concetrated flame and is hotter,in my understanding of it.

 

[Bird]

Many years ago, I went to a welding supply house intending to buy an oxygen/acetylene rig, having never used any kind of welder. The salesman asked where it would be kept . . . in my attached garage. He suggested I use oxygen/MAPP gas instead; said it would be a lot safer, especially since an acetylene leak could be very dangerous in an attached garage, while you would smell MAPP gas before it got to a dangerous level.

I bought that oxygen/MAPP gas rig, took it home, read the manual, and tried, quite unsuccessfully, to weld 2 pieces of steel together. So I took it back to that salesman and told him I didn't think that was going to work. We went out into their shop and he proceeded, with that rig, to demonstrate as pretty a job of welding as you've ever seen. So I went back home and learned to use it; great little rig.:laughing:

I've not personally used oxygen/propane but a farmer neighbor, who was also the fire chief on our volunteer fire department, had an oxygen/propane rig and I've seen him cut thick pipe with it, and saw my brother use it to do some welding on one of our fire trucks; both worked very well.

That same brother had an oxygen/acetylene rig himself, and knew how to use it. I'm no welder, but I've used his oxygen/acetylene rig, and I've used a Lincoln tombstone.

So, if I were in your place, I'd go with the oxygen/propane.

 

[Gary Fowler]

According to the data, propane produces more BTU than Acetylene but when in actual use, it is like Shieldarc says, it take a bit longer to get preheated but once the metal gets hot then it cuts fine. It has a bit of a learning curve when compared to acetylene but they both work. Supposedly you have to have special hoses rated for propane vs acetylene but I have seen folks use acetylene hoses with propane and switch back and forth and doesnt seem to bother them. Maybe the propane softens the hoses over many years or something, but there is hoses made for both so if buying new, just get the dual purpose hose. The only other difference is in the cutting tip itself. Propane requires more gas so the tip (usually two piece) has more preheat orifices. It does put more heat back on your hands also when preheating than acetylene which seems to concentrate the heat closer to the tip. I use acetylene in my rig simply because that is what I am used to using and it lasts a long time. As for smell, a little leak and you will smell it just like propane. Acetylene does smoke a lot if fired up without any oxygen expecially if on a low flow rate. Propane burns cleaner with hardly any smoke, BUT, if you learn to light the torch using O2 and gas at the same time, no smoke and you can braze, weld, cut with the same bottles. With the price of propane now, I am not too sure that it is any cheaper than acetylene to use either, but might be more convenient if you already have a bunch of bottle for your BBQ.
The one thing that propane has over acetylene is the stability. Acetylene gas becomes unstable at pressures over 15 PSI therefore when in the tank it is dissolved in Acetone and stored in a porous concrete like material in the acetylene tank so it can be pressurized to 250PSI. The tanks must always be kept in the vertical position when in use (good idea to keep them vertical at all time) in order to keep the liquid acetone from filling your hoses. Propane has no pressure limits for safety but might not have good tank pressure in extreme cold. I have had to bring my propane BBQ tanks inside to warm up in order to have any vapor pressure when the temps were in the -20C range.

 

[AKwelder]

I have used both and each has its advantage

Acetylene is more common and the parts and tools are cheaper, if you are going to pick up craigslist parts and garage sale items most are not propane. When i was first cutting i i cratered a several tips, and used way to much oxygen. I have heard but do not have proof that propane uses much more oxygen. When heating and bending Acetylene seems to work better for the average user

propane is cheap and everywhere, the standard bottle off your BBQ grill will work, I have seen scrap cutters using a HUGE tank of liquid O2 and a 20 pound propane unit

 

[Shield Arc]

Here's what the propane tips look like that I use on my Victor torch.

 

[yomax4]

Victor makes anice 1pc propane tip too. I cut with Propane or Propylene and save my acetylene for brazing. Usually with Propane or Propylene, They cost the same as Acetylene but last 3 X longer. Big savings if all you do is heat and cut. I will say, of all the alternate fuel gas conversions I have done over the years, For some reason all those folks end up back with Acetylene. It's one of the welding worlds greates mysteries..

 

[dstig1]

Like I am the right guy to answer this... But I can give the reasons why I went propane...

1. New equipment. Got tired of looking for used as many were beat to death. This means you can get whatever you want. I got a decent smith set at the LWS for $250. I could have done a few bucks cheaper online, but not a ton, I needed it sooner rather than later, and these guys treat me right. So I got propane.
2. I can't cut with a torch for crapola, so I figured it really doesn't matter which one cuts "better". My time on acetylene was certainly nothing great...
3. I have a spare grill tank right here, and sure don't have room for yet another tank with acetylene.
4. Propane seems a bit safer than acetylene, though they are both flammable gasses that can make large booms if things go wrong.

So I got that set (Smiths Toughcut lower level line). The guy said that the only real difference was the type T hose (You can use type R in a pinch but it supposedly breaks down in a shortish time) and the tips were made from brass instead of copper (ont he acet rigs) as the flame threw more BTUs near the tip, so they needed to be brass for a bit more heat resistance. He might have been full of it on that last one, but, they were indeed brass vs copper on the same set that was spec'd for acetylene.

These things suck oxygen but use like no fuel. I went through about 3x 125 cf O2 tanks on one project, and the propane 20 lb tanks was still more than half full (then used it on the grill half the summer...). Get the biggest O2 tank you can as the refill cost is much less per unit that way. I can't fit a bigger tank right now or I would have stepped up to the next size (330cf). It is close to $40 for the O2 fill on mine, and like $60 on the larger tank. Hard to argue with those economics.

The physics indicate that there is more BTU output from Propane but a higher actual flame temp from acetylene. That is probably the difference people see on the initial preheat.

I still suck at cutting, but it works just fine overall. I know the problem is me and not the torch. Maybe someday I will get good at it, but I need room for a bigger O2 tank before I am going to spend that kind of time practicing...

My $0.02

 

[muddstopper]

To me the big plus of propane versus Acet is that if I run out, I can go down to the local convience store and do a bottle exchange on a late Saturday, and not have to worry about whether or not the welding supply is open.