Learn more about PASS/START-PROF Pipe Stress Analysis Software
Support spacing is determined by the most restrictive of the following criteria:
Bending stress from weight loads in operating condition must not exceed allowable stress limits.
For intermediate supports (excluding anchor-adjacent spans), analyze the piping as a continuous multi-span beam with uniform loading.
Span length calculated by:
- allowable stress reduced
for pressure loading
Some codes require additional weld joint factors, plasticity factors, etc.
ASME B31.1
ASME B31.3
ASME B31.12IP
ASME B31.4, B31.8
ASME B31.5
ASME B31.9
Sh - Allowable stress at operating temperature
Sy - Yield strength
k - Safety factor (0.25-1.0)
P - Internal pressure
D - Pipe diameter
t - Wall thickness
Wc - Weld joint strength reduction factor
Maximum allowable deflection Vmax:
ASME B31.1: Vmax = min(2.5 mm [0.1 in], 0.5D)
ASME B31.3: Vmax = min(12.5 mm...25 mm [0.5 in...1.0 in], 0.5D)
ASME B31.12IP: User-specified
ASME B31.4, B31.8: User-specified
ASME B31.5: User-specified
ASME B31.9: Vmax = min(6.4 mm [0.25 in], 0.15D)
GOST codes: Vmax = 0.5D
To prevent water accumulation after drainage, GOST codes limit maximum pipe sag to 2% of nominal diameter.
Solve the following system to determine maximum allowable span length L:
For zero slope (h=0):
Minimum recommended sag allowance: max(t, 3 mm), where t = wall thickness. For spans adjacent to bends and flexible elements, use 157 instead of 384, or multiply length L by 0.8.
Support reactions must not exceed allowable capacity R.
This condition is not automatically checked by the software.
Applies to above-ground main pipelines.
This condition is not automatically checked by the software.
Property |
Description |
External diameter, D |
Pipe outside diameter |
Pipe wall thickness, S |
Nominal wall thickness |
Mill tolerance |
Manufacturing tolerance at production. More... |
Corrosion and wear allowance |
Additional wall thickness for corrosion and erosion. More... |
Operation temperature |
Operating temperature in operating condition. More... |
Weld pressure quality factor |
Set according to code requirements.
Calculate automatically
using |
Weld bending quality factor |
Set according to code requirements.
Calculate automatically
using |
Pipe weight |
Uniform pipe weight including attached equipment. More... |
Insulation weight |
Uniform insulation weight. More... |
Product weight |
Uniform fluid content weight. More... |
Operation pressure, P |
Operating pressure in operating condition. Required for all codes except SNiP 2.05.06-85. More... |
Working pressure, Pwork |
Design working pressure. Required for SNiP 2.05.06-85. More... |
Test product |
Fluid medium used for pressure testing. |
Test pressure |
Hydrotest pressure. |
Test temperature |
Temperature during pressure testing. Average pipe metal temperature during test. Typically ambient temperature (+20°C). |
Piping slope |
Pipe slope angle. Required for accurate sag and deflection calculations. |
Steel grade |
Pipe material from the materials database |
Pipe. Above-ground > Span Length Analysis
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