When designing piping systems in chemical plants or industrial facilities, determining proper support spacing is not just about appearance or “what feels right.”
By applying the principles of mechanics of materials, you can calculate the bending stress and deflection to ensure safety and reliability over the long term.
This article walks you through how to estimate the required support spacing for a 2-inch (50A) carbon steel pipe using basic mechanical formulas.
Even if you’re a beginner, this guide will help you move from “rule of thumb” to “calculated confidence.”
1. Calculation Model
We’ll use a simply supported beam model under uniformly distributed load — a standard assumption for pipe spans between supports.
2. Parameters
- Pipe: 50A (SGP)
- Inner Diameter: 52.9 mm
- Wall Thickness: 3.8 mm
- Material: Carbon Steel (Elastic Modulus E = 2×10¹¹ N/m²)
- Weight per Unit Length (w):
w=5.31 kg/mw = 5.31 \text{ kg/m}w=5.31 kg/m
3. Key Formulas
Bending Stress:
$$σ=\frac{M}{Z}=\frac{wl^2}{8Z}$$
Deflection:
\$$δ=\frac{5wl^4}{384EI}$$
4. Section Properties
Moment of Inertia (I):
π/32*{(60.5/1000)4-(52.9/1000)4}=2.73×10-7m4(27.3cm4)
Section Modulus (Z):
2.73×10-7/(60.5/2/1000)=9.03×10-6m3(9.03cm3)
5. Results
Bending Stress Criterion:
5.31/8/9.03×10-6×9.8=0.72×106Pa(0.72MPa)
Deflection Criterion:
(5*5.31)/(384*2×1011*2.73×10-7)=26.55/20.9664=1.26×10-6m(1.23×10-3mm)
From these results, the bending stress limit is more restrictive.
For a 50A pipe, a practical support spacing is about 3 to 4 meters.
🧩 Summary
| Criterion | Maximum Span |
|---|---|
| Bending Stress | ≤ 3.7 m |
| Deflection | ≤ 6.3 m |
In practice, use 3–4 m spacing for 50A carbon steel pipes.
Larger diameters or heavier loads require shorter spacing or stronger supports.
Understanding these calculations helps you design safer, longer-lasting piping systems — and builds confidence in your engineering decisions.
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