Expert4PVC Consulting

Expansion Loops & Developed Stress

Pipe Diameter:
Pipe Material:
Pipe run :


Min. Temp.:


Max. Temp.:


Pipe Outside Diameter:
Pipe Inside Diameter:
Wall Thickness:
Dimension Ratio:
Coefficient of Expansion:
Temperature Range: (ΔT)
Change in pipe length :
Modulus of Elasticity: (E)
Allowable Working Stress:
Developed Loop Length: (L)
Area of Pipe:
Thermal Induced Stress: (St)
Longitudinal Force:

Expansion Loop 1 Expansion Loop 2 Expansion Loop 3
Rigid or restraining supports should not be placed within the developed length (L) of an expansion loop, offset or bend. Piping support guides should restrict lateral movement, yet direct axial movement into the compensating configurations. Valves and other concentrated loads should not be located within the developed length.

This calculator generates data for thermal expansion loops, thermal induced stress and the longitudinal forces. It offers several standard commercial sizes of pipes, although all combinations of pipe material, Schedule or SDR may NOT be valid!
• Basis of Calculations •
Expansion loops and offsets should be constructed with straight pipe and 90° elbows which are solvent cemented together. If threaded pipe is used in the rest of the system, it is still recommended that expansion loops and offsets be constructed with solvent cement in order to better handle the bending stresses incurred during expansion The expansion loop or offset should be located approximately at the midpoint of the pipe run and should not have any supports or anchors installed.
• • Thermal Stress • •
If thermal expansion is not accommodated. it is absorbed in the pipe as an internal compression. This creates a compressive stress in the pipe. The stress induced in a pipe which is restrained from expanding is calculated with the following formula:
St = E x expansion x ΔT

• • • • Caveat • • • •
The information and calculations provided are based on data which we believe is reliable. Expert4PVC Consulting, however can not take responsibility for the information or data contained herein and no warranty of performance for any specific purpose or particular installation of any product is expressed or implied from this calculator. Results based on the equations shown and parameters entered.
©2011 Expert4PVC Consulting rev. 20-feb-12