# Spacing Between Piping Supports

Spacing between supports is the minimum value from the following conditions:

### Stress Condition

Bending stress from weight in a Piping heated to operation temperature must not exceed allowable

Spacing between intermediate supports for any gap except that adjoining to anchors is determined from the analysis of a Piping as a continuous multi-span beam with an uniform load.

Spam length calculated by equation:

- allowable stress reduced due to pressure load

Also some codes require to add 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 - pressure

D - diameter

t - wall thickness

Wc - weld joint strength factor

### Allowable Deflection (Vmax) Condition

Allowable deflection Vmax is:

• 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 specified by user

• ASME B31.4, B31.8 specified by user

• ASME B31.5 specified by user

• ASME B31.9 Vmax=min(6.4 mm [0.25 in]; 0.15D)

• GOST codes Vmax=0.5D

### Allowable Sag (Dmax) Condition (GOST codes)

To prevent sags where the water stays after discharging of the pipe, the maximum allowable piping sag in GOST codes is limited by 2% of nominal diameter

The following system of equations should be solved to find the maximum allowable span length L:

For zero slope (h=0) the equation is used:

It is recommended to take allowable sag not less than min(t, 3 mm), where t - is wall thickness. For spans near the bends and other flexible elements the 157 value should be used instead of 384. Or length L should be multiplied by 0.8.

The load on supports must be less then allowable R.

This condition is not checked by program

### Absence of Resonance in the Wind Flow

This condition is used for above ground main pipelines.

This condition is not checked by program

### Input data

 Property Description External diameter, D External pipe diameter, D Pipe wall thickness, S Nominal wall thickness Mill tolerance Mill tolerance at the time of production. More... Corrosion and wear allowance Corrosion and wear allowance (working mill tolerance) for wall thickness. More... Operation temperature Operation temperature in operation state. More... Weld pressure quality factor Set based on standards. Can be calculated automatically by pressing . More... Weld bending quality factor Set based on standards. Can be calculated automatically by pressing . More... Pipe weight Uniform weight of the piping and adjoining equipment. More... Insulation weight Uniform insulation weight. More... Product weight Uniform product weight. More... Operation pressure, P Operation pressure in operation state. Set for all standards except SNIP 2.05.06-85. More... Working pressure, Pwork Working pressure (based on standards). Set when analyzing with SNIP 2.05.06-85. More... Test product Product used for testing Test pressure Pressure during testing Test temperature Operation temperature in  test state. Average wall (metal) temperature along the piping during testing. Testing is usually done without product pre-heating; therefore, at air temperature. Usually set as Тtest = +200С. Piping slope Piping slope. Must be input for accurate calculate of spacing calculation conditions 2 and 3 Steel grade Pipe material from the materials database