Hoop and Longitudinal Stress – Gas

Contents

Introduction

These stresses are used in most calculations for road and RR crossing, spans, blasting, streams, etc. before deciding on the safety of the pipe.

Live hoop and longitudinal stress must be below seam and girth weld fatigues limits. Outside force stresses must be known for proper evaluation.

S_H=\frac{PD}{2t}

S_H=\frac{PD}{2t}

Where:
𝑆_𝐻 − Hoop stress (psi)
𝑃 − Pipe internal pressure (psi)
𝐷 − Pipe outside diameter (in)
𝑡 − Pipe wall thickness (in)

S_L=\frac{PD}{4t}

S_L=\frac{PD}{4t}

Where:
𝑆_𝐿 − Longitudinal stress (psi)
𝑃 − Pipe internal pressure (psi)
𝐷 − Pipe outside diameter (in)
𝑡 − Pipe wall thickness (in)

Select the Hoop and Longitudinal Stress application from the Design & Stress Analysis Module
To create a new case, click the “Add Case” button
Enter Case Name, Location, Date and any necessary notes.
Fill out all required Parameters.
Make sure the values you are inputting are in the correct units.
Click the CALCULATE button to overview results.

If you need to modify an input parameter, click the CALCULATE button after the change.
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To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
To generate a REPORT, click the REPORT button.
The user may export the Case/Report by clicking the Export to Excel icon.
To delete a case, click the DELETE icon near the top of the widget.

Restrained versus Unrestrained Pipe (Difference in Gas vs. Liquid)?

ASME B31.4 liquid and B31.8 gas codes include calculations for the net longitudinal compressive stress that must be applied only for a restrained line that equates to a low (less than 2%) longitudinal strain. This stress status is characteristic to underground pipelines located some distance away from above ground piping facilities.
Unrestrained lines means those above ground sections of piping without axial restraint as with buried pipe with soil. In others words the soil exerts substantial axial restraint, but not fully restrained. Check Out
What is the Maximum Span Length of rev1?

Regarding span factors with and without water are based on bending stress and deflection. Larger diameter pipe spans require saddles for stability. Many standards that require pipes to be filled with water are based on bending and shear stresses not to exceed 1,500 psi and a deflection between supports not exceed 0.1 inches. Check Out
What is the model used for Thrust at Blow-Off?

HUBPL uses the equation from the DOT Inspectors Handbook:
TF = 0.5042 * G*Q^2/(P*D^2)
Check Out

Updated on December 15, 2023