Calculation
L = k · di^0.67 (di in mm, L in m)
An empty, uninsulated pipe (k = 0.3) tolerates a wider support spacing than a filled, insulated pipe (k = 0.2) because its self-weight is much higher.
L = k·di^0,67 (Richtwert, AD2000-HP100R)
Support spacing of horizontal pipe runs
An empty, uninsulated pipe (k = 0.3) tolerates a wider support spacing than a filled, insulated pipe (k = 0.2) because its self-weight is much higher.
MINTSI
02
Result
Select a target and calculate.
Understand the inputs
- Support spacing L — Recommended maximum spacing between two supports.
- Execution factor k — 0.3 for an empty, uninsulated pipe; 0.2 for a filled (water) and insulated pipe.
- Pipe inside diameter di — Inside diameter per the applicable pipe standard.
Example
k = 0.3 and di = 100 mm give L ≈ 6.56 m.
Assumptions and limits
Experience-based guideline for straight runs without point loads such as valves or branches; the binding values are the allowable spacings per AD2000 code sheet HP100R.
Understand Support spacing of horizontal pipe runs
This calculator estimates the approximate support spacing of a horizontal, straight steel pipe run from the pipe inside diameter.
What does this quantity describe?
The rule of thumb L = k·di^0.67 (with di in mm and L in m) gives a guideline value for the support spacing of horizontal steel piping, depending on the execution factor k. An empty, uninsulated pipe (k = 0.3) tolerates a wider support spacing than a filled and insulated pipe (k = 0.2), because its self-weight is much higher.
Think of the sag limit on a clothesline: a heavier, wet garment (a filled, insulated pipe) needs closer support points to avoid the same sag as a light, dry one (an empty, uninsulated pipe).
Formula and variables
L = k · di^0.67 (di in mm, L in m)
L = k · di^0.67 (di in mm, L in m)di = (L/k)^(1/0.67)k = L / di^0.67
| Symbol / input | Meaning |
|---|---|
| Support spacing L | Recommended maximum spacing between two supports. |
| Execution factor k | 0.3 for an empty, uninsulated pipe; 0.2 for a filled (water) and insulated pipe. |
| Pipe inside diameter di | Inside diameter per the applicable pipe standard. |
Choose the inputs correctly
k is the execution factor (0.3 for an empty, uninsulated pipe; 0.2 for a filled and insulated pipe), and di the pipe inside diameter per the applicable pipe standard.
How to use the calculator
Choose k according to the operating state (empty/filled, insulated/uninsulated) and enter di to get the recommended support spacing L.
Worked example
k = 0.3 and di = 100 mm give L = 0.3 · 100^0.67 ≈ 6.56 m.
Understand the result and units
L ≈ 6.56 m is the approximate recommended maximum spacing between two supports for this empty, uninsulated pipe. For binding design values, refer to the allowable spacings per AD2000 code sheet HP100R.
di is given in mm, L in m; k is dimensionless. The formula is explicitly defined only for di in mm and L in m.
Why di is in mm and L is in m
As with the fillet weld throat-thickness rule of thumb, this is an empirical, non-dimensionally-homogeneous equation: the exponent 0.67 and the execution factor k were calibrated specifically for di in millimetres and L in metres. Plugging di in in a different unit would give a wrong numeric value for L, since the power function does not scale linearly with the unit. This calculator therefore always computes internally with di in millimetres, regardless of the display unit chosen at the input field.
Typical applications
The rule of thumb is used in the preliminary design stage of piping systems to quickly estimate a sensible number and arrangement of pipe supports for straight runs.
Assumptions, limits and common mistakes
The guideline applies to straight sections of horizontally installed steel piping without point loads such as valves, branches or compensators. It does not replace the binding support-spacing calculation per AD2000 code sheet HP100R, which accounts for additional factors such as deflection limit and allowable bending stress.
Common mistake: A common mistake is using the pipe outside diameter instead of the inside diameter di, or choosing k without regard to the actual operating state (empty/filled).
Frequently asked questions
Which k value do I choose for a water-filled, insulated pipe?
k = 0.2, since the higher self-weight from filling and insulation requires a tighter support spacing.
Is L a binding requirement?
No, it is an approximate guideline value; the binding allowable spacings are found in AD2000 code sheet HP100R.
Does the formula apply to vertical pipe sections too?
No, it explicitly applies to horizontally installed, straight steel piping; vertical sections have different support requirements.
What if a valve or branch sits within the section?
Then an additional point load must be considered beyond the plain rule of thumb, and verified separately.
Why doesn't L scale proportionally with diameter?
Because the exponent 0.67 is less than 1: larger pipes gain stiffness at a lower rate than their added self-weight, so support spacing increases at a diminishing rate with diameter.