Often cheaper than oil and electric heating, natural gas is used in numerous applications, including cooking on grills and stoves, heating water, running furnaces and space heaters and fueling portable fireplaces and other small household appliances and generators. However, because natural gas is flammable and heavier than air, if the gas supply lines are not properly connected, they can leak and cause a fire or explosion. Gas lines, therefore, must be connected using flare fittings or other approved fitting methods.
One type of natural gas pipe fitting is the common flare fitting used in plumbing. In this method, the pipe has a nut or flare fitting inserted over the end, then the end is flared out or widened out, much like the end of a tuba or other cone shaped object, using a special tool called a flaring tool. After this is done, a second cone shaped fitting can be inserted into the newly flared end of the pipe, and the nut that was inserted over the end of the pipe---before it was flared---can be tightened down so that the metal is crushed together, preventing any leaks or other problems. This method is used with copper tubing for gas lines.
A second type of pipe flare is used with corrugated stainless steel tubing (CSST), which is a type of gas pipe that is ribbed and that self flares when the fittings are tightened. Using CSST tubing is generally easy, as all you have to do is cut the tubing to length, insert the fittings over the end of the tubing, then tighten them together. They will crush together and flare the tube perfectly, without any need for special tools. CSST tubing is used in the natural gas industry as a safe and efficient method for connecting gas lines.
Double flaring is a type of gas line flare that is usually found in high pressure applications. Double flaring involves beginning with a standard flare, then rolling the edges of the tubing back over the initial flare to create a stronger, more rigid flare than a standard flare fitting is capable of forming.
