How does AutoPIPE calculate the Short, Long, 3D, and 5D bend radius for piping?
Open the model input grids or Bend Dialog, place cursor in the Bend Radius field and press keyboard F1 key. Help on this section will appear.
This will answer most questions about how the program calculates the automatic bend radius values.
Test Question: After reading this information above, is the bend radius based on Nominal Pipe diameter. or OD (Outside Diameter) ?
Answer: Correct, Both values are used. Nominal Pipe size will be used until the OD => 13" (330.2 mm), at this point the program will use the OD values when calculating the automatic Short, Long, 3D, or 5D bend radius values.
However, when using Nominal Pipe size = NS, the user is required to insert a value for OD (see image above).
How does the program calculate a Nominal pipe size for NS piping?
As mentioned in the help, the program still uses the same logic above:
if the pipe OD < 13" use Nominal Pipe value
if the pipe OD > 13" use the OD pipe value
Using the example information above, Nominal = NS, OD = 50 mm.
From help information above:
Short = Dia x 1
Long = Dia x 1.5
3D = Dia x 3
5D = Dia x 5
Dia = 50 mm
Short = 50 x 1 = 50 mm
Long = 50 x 1.5 = 75 mm
3D = 50 x 3 = 150 mm
5D = 50 x 5 = 250 mm
Again, compared to the model input listing above, the Nominal dia does not = 50 mm.
What is the next lowest Nominal value?
To illustrate the next lowest value, input a series of new PIPE IDs with various Nominal pipe sizes.
Notice that if Actual OD = 50 mm the next lowest Nominal = 40 mm with a Actual OD = 48.2 mm, because when Nominal = 50 the Actual OD > 50 mm.
Run the calculations with Dia = 40 mm
Short = 40 x 1 = 40 mm
Long = 40 x 1.5 = 60 mm
3D = 40 x 3 = 120 mm
5D = 40 x 5 = 200 mm
Again, compared to the model input listing above, the Nominal dia does not = 40 mm. Why?
Recall that all calculations in AutoPIPE are based on English units, the results of the calculations are then converted into what ever units specified on the General Model Options dialog. In this example Input and Output Units = SI.
Therefore, what is the next lowest Nominal pipe size in English units:
50 mm = 1.97 inches
The next lowest Nominal Pipe for 50 mm dia = 1.5 inches (38.1 mm) because when Nominal = 2.0 inches (50.8 mm) which is > 50 mm.
Run the calculations with Dia = 38.1 mm
Short = 38.1 x 1 = 38.1 mm
Long = 38.1 x 1.5 = 57.15 mm
3D = 38.1 x 3 = 114.3 mm
5D = 38.1 x 5 = 190.5 mm
Compare to input listing with rounding values:
Conclusion, AutoPIPE used 38.1 Nominal dia to calculate automatic bend radius values.
"Bend" - Model Input listing sub-report