Maximum Allowable Pullback Force Analysis
Where the pullback force calculator tells you how much tension a bore will demand, this tool answers the complementary question: how much tension the pipe can safely take. It computes the maximum allowable pullback force and the minimum allowable bend radius that keep the combined installation stresses — tensile plus bending plus external hoop — within the code-permitted limit.
Running both together closes the loop on an HDD design: the demanded pull force must stay below the allowable pull force, and the designed bore radius must stay above the minimum allowable radius, for the pipe grade and wall thickness you have specified.
Open in the Pipeline Planning Toolbox — Free 7-Day TrialWhat it determines
- Maximum allowable tensile pull force for the pipe grade and wall
- Minimum allowable bend radius at that tension
- Combined-stress utilization against the code limit
- The governing limit — tensile, bending, or combined
How the limit is set
For steel pipe, allowable installation stress is expressed as a fraction of specified minimum yield strength (SMYS); the calculator solves for the tension and radius at which the combined stress reaches that ceiling. For PE pipe, the governing limit is the material’s safe pull strength, which is reduced for the duration of the pull and for temperature per ASTM F1962 and PPI guidance.
The minimum bend radius result is especially useful during bore-path layout: it sets the tightest curve the profile can use before bending stress alone consumes the available margin.
Frequently asked questions
How is minimum bend radius related to pullback force?
Tighter radii add bending stress and amplify tension through the capstan effect, leaving less margin for tensile load. The maximum allowable pull force therefore drops as bend radius decreases — the calculator returns the pairing that just reaches the code limit.
What fraction of SMYS is used for HDD installation?
Allowable installation stress is a code- and operator-specified fraction of SMYS; the exact value depends on the governing pipeline code and project specification. The tool lets you set it so the check matches your design basis.