Maximum Allowable Pipe Span Length

Step 1: Variables Definition 

𝐷 − Pipe Outside Diameter [in]

𝑊 − Weight [lb/ft], includes water weight if hydrostatic testing is specified

MOAP − Maximum Allowable Operating Pressure [psi]

SMYS − Specified Minimum Yield Strength or Grade of Steel [psi]

OP − Operating Pressure [psi]

𝑡 − Pipe Wall Thickness [in]

𝑆−Section Modulus [in²]

𝐼−Moment of Inertia[in⁴]

𝑒− Modulus of Elasticity (29000 ksi)

𝐻 − Hoop Stress [psi]

𝐵 − Bending Stress [psi]

𝑀 − Bending Moment [ft−lb]

𝐿 − Span Length [ft]

𝑑 − Deflection [in]

Step 2: Calculate Hoop Stress

Where 𝑃 = MOP

Step 3: Calculate Maximum Allowable Bending Stress

 Solve Von Mises Equation through Quadratic Equation, and then solve for Bending Stress B

Step 4: Calculate Maximum Allowable Bending Moment

Step 5: Calculate Maximum Span Length L, due to Bending

Step 6: Calculate Maximum Span Length L, due to Deflection

Input Parameters

1. To create a new case, click the “Add Case” button
2. Select the Maximum Allowable Pipe Span Length (G) module.
3. Enter Case Name, Location, Date and any necessary notes.
4. Fill out all required fields.
5. Make sure the values you are inputting are in the correct units.
6. Click the CALCULATE button.

• Nominal Pipe Size
• Wall Thickness (in.)
• Grade
• Pipe Class
• Youngs Modulus of Steel (psi)
• Poisson’s Ratio for Steel
• Average Unit Weight of Steel (Calculated)
• Pipe installed after November 11, 1970 (Y/N)

Outputs/Reports

1. View the results.
2. If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
3. To SAVE, fill out all required case details then click the SAVE button.
4. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
5. To generate a REPORT, click the REPORT button.
6. The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
7. To delete a case, click the DELETE icon near the top of the widget.

Related Links