Bend Classifications 3D vs 3R
Bend Classifications 3D vs 3R
(OP)
I have been told that a pipeline 3D bend is equivalent to a bend with a radius of 3 x the outside diameter of the pipe, hence 3D. I have also been told that a 3R bend means the same thing as a 3D bend. They are both 3 x the outside diameter of the pipe. A lot of people get confused about the R in 3R. Does it stand for radius? If it does then how can a 3D and a 3R be equivalent?
Can anyone shed some light on the background of these two terms?
Can anyone shed some light on the background of these two terms?





RE: Bend Classifications 3D vs 3R
I would only expect to see "R" (radius) specifically mentioned on a fabrication drawing as a hard dimension, since the bend radius can theoretically be anything while the "D" (nominal pipe diameter) is obviously fixed.
Piping Design Central
RE: Bend Classifications 3D vs 3R
RE: Bend Classifications 3D vs 3R
Not much else you can say about that.
you must get smarter than the software you're using.
RE: Bend Classifications 3D vs 3R
Like so many things, it is very simple when you use all the words, but "common" shortcuts are only common to insiders. We so often do ourselves a disservice by failing to fully specify what the heck we're talking about.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist
RE: Bend Classifications 3D vs 3R
you must get smarter than the software you're using.
RE: Bend Classifications 3D vs 3R
I've never heard of anyone calling a 3D radius bend a 3R bend before now.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Bend Classifications 3D vs 3R
I often see manufactured elbows referred to as "3R" even though it doesn't really communicate. In field bends, some surveyors have really odd designations. I've only seen the 165° terminology on one alignment sheet--I sent it back and had the draftsman use the 15° terminology, I had visions of pipe bent back on itself. The draftsman said "but you can measure the angle my way, your way you have to measure to a virtual line". He was right, but running counter to custom and I wasn't going to let that cat out of the bag.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist
RE: Bend Classifications 3D vs 3R
LittleInch, your example is only 15 degrees away from a 180!
Piping Design Central
RE: Bend Classifications 3D vs 3R
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist
RE: Bend Classifications 3D vs 3R
The ohnosecond was when I realized that I wrote 180 but wanted 360.
Piping Design Central
RE: Bend Classifications 3D vs 3R
you must get smarter than the software you're using.
RE: Bend Classifications 3D vs 3R
Anyway it's easy enough to figure out, the interior angle is simply 2 x the deflection angle.
you must get smarter than the software you're using.