How to Flare a Stainless Tube

Creating a flare on a stainless steel tube is simple with tool kits designed specifically for that purpose. Most flare tool kits are designed for light-duty materials such as aluminum, copper, or soft steel. Stainless steel tube must be flared with a heavy-duty ratcheting flare tool kit. The ratchet feature prevents over-tightening. These kits cost more than light-duty kits but in some cases where corrosion resistance is necessary, such as brake lines, there is no substitute for stainless steel.

Instructions

1

Slide the tube cutter over the tube to the cutting location and close the cutter onto the tube. Hand-tighten the knob and rotate the cutter around the tube slowly, tightening the cutter every two rotations, until a groove appears. Continue until the tube breaks easily with hand pressure, as if you were breaking a stick.

2

Hold the outside corner of the tube at approximately 30 degrees against a file and rotate the tube against the file only until the rough edges are smooth, no more. To remove the inner, sharp edges, use the tip of the file to scrape the inner rim of the tube end. A chamfer tool may be used for the inner rim, if available. A chamfer tool is a cone-shaped bit that bevels the inner rim of a hole when rotated against the hole opening.

3

Any fittings that will be used later must go on the tube now. They will not fit after the flare is complete. Slide them over the end of the tube and push them down the length of the tube out of the way of the flare tool.

4

Insert the tube in the matching hole in the flare tool bar. One side of the holes in the bar have beveled edges to allow the tube to expand. The end of the tube should be facing out of the beveled side of the holes and flush with the flat surface of the bar. Tighten the bolts in both ends of the bar securely, starting with the bolt closest to the tube.

5

Slide the yoke over the bar and center the flaring cone over the tube. Some flare tool clamp bars tools have a line to indicate where to clamp the yoke. Tighten the yoke's side clamp onto the bar.

6

Apply a few drops of oil on the cone and tube end. Twist the feed screw handle clockwise until it clicks, and then turn it two more times to rub against the inside of the flare, making it smooth.

7

Turn the feed screw counterclockwise until it is above the flared tube. Loosen the side clamp and remove the yoke from the bar clamp. Loosen the bolts that hold the bar clamp together. Remove the flared tube and inspect the flared end. The flare must be smooth and free of cracks to seal properly.