# pipe bending chart

It was more a straight line than a bend! deduct 6 inches for a 90. Many protractors are very difficult to read exactly what you want, and 1 or 2 degrees off is very common. I always start with the basic bends first. I'd eye off the 90 right, but I need a banger at starting height. This leaves the pipe horizontal, with the end being bent upward. 3D and 5D bends are most common use in long pipelines, since they provide better efficiency in changing directions. The relatively simple math formulas of sine, cosine, and tangent can be used to determine the angles of the triangle, and, therefore, the necessary angles of your pipe bend(s). The math formulas we will be using are sine, cosine, and tangent. The 2.5" per inch of rise applies only to a 22/45 saddle, not a 10/22 or a 30/60 degree saddle. When calculating bend allowances to determine the cut length of HDPE conduit or PVC pipe, one must calculate from the center line radius (CLR) of the finished, bent pipe. Dan Harmon (author) from Boise, Idaho on September 15, 2014: That depends on what you are doing. Note that making concentric bends requires using some additional math not discussed in this article. You would have to check in practice, but I suspect that the NEC figure is to the inside of the bend, meaning that the loss will be 3/4" less than what is calculated: the length of the completed bend will be 3/4" more than the minimum radius. Question: how do i figure out the development for a 15 degree saddle bend if the center line radius is 25"? Your calculator will give you the sine, cosine, and tangent of any angle. Dan Harmon (author) from Boise, Idaho on October 05, 2010: Indeed it is, although few electricians realize it or use it. Hahahahah. It's much appreciated. BendWorks ® Software. What is the conduit shrinkage—that is, the amount by which the center of the bend will be closer to the end of the conduit than the measured length of pipe? Dan Harmon (author) from Boise, Idaho on April 13, 2015: LOL - that's the way it goes, John. AESS Fabrication; Curved Architectural Stairs; Heavy Fabrication. I'm sure the problem is in the bending process - the wrong angle (are you using the bender on it's side and measuring with the rod that comes out to indicate bend? Have you picked up an error elsewhere in the article that I missed when proofreading? Octal Pipe Fittings is engaged in providing completely piping solutions for industrial companies. One I use all the time is the "rolling offset.". Answer: Not in the sense of the formulas given here. (Or send inquiry to info@octalpipefittings.com). Then mark line "C" using same measurement as line "B" above but mark on opposite side of center Line "A". Will take days to understand and experience I'm sure. The tube is also loosely held by two other dies, the wiper die and the pressure die. This is great and wow... Love it so much very educating. The "B" bend is not at the same point on the bender, but at the center of the chosen degree for the center bend. In the diagram below, the heavy black line represents the bent piece of conduit; the green triangle shows some useful lengths and angles. So, we have 2.125" x tan(15), or 2.125" x .268, which gives us .5695. It is very important to get the two marks at exactly the same place on the bender, and it isn't always easy with big pipe. But you can block it in and print it that way. It is a pleasure to share what I have learned over the years, and I'm always glad when someone finds it useful. There is a use for it!!! shrink = hypotenuse(offset bend marks) - cos of angle X hypotenuse. Yes, the very word ("math") scares a lot of people off, but it really isn't hard. Maximums are as high as you wish. The black line represents an offset bend in a tube; the red triangle represents the triangular geometry this offset creates. After you’ve selected the appropriate die for bending your pipe, based on the pipe’s outside diameter and wall thickness, you should be able to find the radius of the bend. Multiply the radius of the bend you want to make by 6.28, then by degrees, bend and divide by 360. There will be some "shrinkage", which can be found by the math formula of Shrink=4.25-4.25*cos(22) = .31" in your case. ### Subscribe

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