Oxy-Fuel Cutting with Acetylene
Burning fuel in the presence of oxygen produces an intensely hot flame that has been used to cut and weld metal for more than a century. For the operator, the only decision that needs to be made before production begins is the type of fuel to use. Common fuels include acetylene, propane, and propylene and each has benefits and detractions. Acetylene, for example, is expensive and prone to explosions under high pressure (such as in compressed gas tanks). However, despite its cost and safety risks, acetylene is still the primary fuel used in oxy-fuel processes. Why?
Acetylene is Still the Number One Cutting Gas
There is two reasons that acetylene is still the number one fuel of choice for oxy-fuel cutting and welding processes and the reason is quite simple. It is the longest established cutting gas and acetylene burns the hottest of any of the commonly used fuels. For obvious reasons, a high temperature is effective for melting pieces of metal, either for purposes of fusing or separating, and acetylene is second to none in this regard. Whereas a propane flame burns at about 2,000 degrees Celsius in oxygen, acetylene burns in excess of 3,100 degrees Celsius and propylene burns at 3,100 C. That vast difference in temperature makes acetylene an excellent fuel for cutting and welding, especially when working with thin metals.
Better for Thin Metals
The reason that acetylene is best for thin metals is because the high heat allows for fast, precise cuts. But, the reason acetylene is not as suited for a large piece of metal has to do with the limitations of the fuel. Acetylene is highly unstable under pressure and must be stored and handled carefully. As part of the safety measures, acetylene tanks are filled with a porous material and acetone, into which the acetylene is dissolved. All of this means that acetylene is limited to a delivery pressure of no more than 15 psi. Overall, acetylene has an extremely hot localized flame but has a lower total heat output potential than propylene or propane. So, when applied to very thick pieces of metal, acetylene may cause excessive splatter if the pre-heating process takes too long. Generally the thicker the metal to be cut the more appropriate Propylene becomes as a cutting gas.
Acetylene Starts Cutting Faster
While acetylene may not be the best fuel for large single projects, the high heat and localized flame can increase production and cut quality for appropriately sized projects where many small cuts need to be made. On top of increased production and quality, acetylene also uses less oxygen during combustion that the alternative fuels, a characteristic though any savings are offset by the increased cost of acetylene. All in all, even though acetylene fuel costs are high, it does have some money saving characteristics, especially if production rates are increased.
Acetylene is the most unstable and expensive fuel for oxy-fuel cutting and welding, but it remains a popular choice among professionals and hobbyists. For clean cuts of thin metals and high productions, acetylene is still the leader.
Acetylene Safety Issues
Due to its inherent instability and bad safety record we have decided not to stock acetylene. Storing, transporting and using acetylene has not got a good safety record.
