A flare wrench, also known as a flare-nut wrench, tube wrench or line wrench is used for gripping the nuts on the ends of tubes (like automotive brake lines and household Plumbing). It is similar to a box-end wrench but, instead of encircling the nut completely, it has a narrow opening just wide enough to allow the wrench to fit over the tube. This allows for maximum contact on plumbing nuts, which are typically softer metals and therefore more prone to damage from open-ended wrenches. See images of flare nut wrenches by searching Google and see what purchase links pop up. Cheers
An open end wrench.
Open end, box end, with 6-point or 12 point box end, flare end, ratcheting end-wrench, Crescent (or aka adjustable), crowsfoot, pipe wrench and more
Flare nut wrenches are just small wrenches, usually 5/16 or similar with a slot to pass over the pipe.
Use a flare nut wrench, and hold whatever it is screwed into from turning to prevent damaging the tubing
You will need a 5/8" flare nut wrench and a 1" open end wrench to access the fuel filter. To be safe, disconnect the neg battery cable from battery. Follow the fuel line to the carburetor. Slide the 5/8" flare wrench over on to the 5/8" flare nut at the end of the fuel line then slide the 1" open end wrench onto the larger fitting at the carburetor and turn the flare nut CCW from the fitting while holding the 1" fitting from turning. A small amount of fuel will run out so have some rags handy. With the flare nut removed and fuel line pulled out from the large fitting use the 1" open end wrench to remove the large fitting from carb. Take note of the order and direction of parts as they come out. Be sure the thin round nylon gasket doesn't get lost and remains attached to the inside end of the large fitting, this is what seals the fitting to the carburetor body. Reverse order to install.
The only reason there is problem in loosening the fuel lines is the wrong wrench is being used, which can slip on the fittings. A flare nut wrench should be used and these are then easy to properly loosen and tighten.
Your question needs some clarification. If you meant to say how do you replace the front/rear flexible brake hoses (assuming you have rear disc) or how do you replace all of the brake lines on my Accord that would greatly help direct a more direct response. You should have specific hand tool before changing your brake lines, and that is a flare nut wrench. I have a 10mm and 12mm flare nut wrench that works well. This wrench if thicker than a standard wrench and one side is approximately 75% closed (like a box end wrench) to allow for more contact area and reduce stripping the flare nut. There are also clips that hold the line to a bracket where the 'hard' & 'flexible' lines connect. Leave this in-place until you have loosened the connector (and install the clip) before you tighten the connector
The brake lines are 1/8 inch. Rather than buy lines and bend and flare the ends of them it is just as economical to buy pre-formed lines at the auto parts with the ends already flared and the flare nuts on them. Use a flare nut wrench to loosen and tighten the nuts.
It is best to use a flare nut wrench and a narrow open end wrech. Use penetrating oil prior to taking it out.
AP Flare = Atmospheric Pressure Flare
Its (7/8) 22.5mm but you'll need it to be short and thin . I'm making one . The other size is 16mm(5/8) . a regular flare nut wrench will work on it .
the fire sent a flare into the air.the flare from the fire was warm.