Pull Force Calculator PE-HD
Calculates allowable pull forces for PE pipes in HDD applications as a traceable engineering estimate.
The calculator determines the allowable pull force as a result band (conservative / recommended / optimistic) and displays all intermediate values transparently in the calculation trace.
Notice: This quick check is for orientation purposes only. The results do not replace a project-specific design. Dimensioning and approval are the responsibility of the responsible engineering office. All information without guarantee. Full Disclaimer
Application Guide
When to use this calculator?
The pull force calculator is used for pre-planning and plausibility checks of pull-in operations during trenchless pipe installation (Horizontal Directional Drilling – HDD). It answers the key question:
What is the maximum tensile force the PE pipe can withstand without exceeding the allowable axial stress?
Typical use cases:
- Site preparation: Quick comparison of allowable pipe tensile capacity with a separately determined project load.
- Bid calculation: Plausibility check of the pipe dimension for a given route geometry.
- Quality assurance: Comparison of actually measured pull force against the calculated limit.
Standard vs. Pro Mode
| Standard | Pro | |
|---|---|---|
| For whom? | Quick estimates, sales, site checks | Detailed planning, engineering offices |
| Input | Pipe dimension via dropdown (DIN 8074 presets) | Free input of all parameters |
| Parameters | Material + SDR + pull duration | + Temperature, safety factor, bend radius, bending factor |
| Result | Single value + range | Single value + range + full calculation trace + impact factor chips |
Input Fields Explained
Pipe Dimension (dₑ × s)
- dₑ = Outside diameter in mm (e.g. 110, 225, 400)
- s = Wall thickness in mm (determines SDR class: SDR = dₑ / s)
- In Standard mode, only standardized combinations per DIN 8074 / ISO 4427 (EN 12201-2) are offered.
Material
- PE 100 / PE 100 RC – High-density PE types with MRS 10 (σ = 10 N/mm²). PE 100 RC additionally offers enhanced stress crack resistance (RC = Resistance to Crack). Standard material for pressure pipelines.
- PE-HD (DIN 16874) – Material with MRS 8 (σ = 8 N/mm²).
Safety Factor S (Pro)
The safety factor accounts for unknowns such as friction, borehole deviations and material tolerances.
| Value | Meaning |
|---|---|
| S = 1.00 | Optimistic – ideal conditions, for comparison only |
| S = 1.25 | Recommended internal planning value; this factor is not specified by DVGW GW 321 |
| S = 1.50 | Conservative – increased safety for difficult soil conditions |
Pull Duration
Pull duration is represented by discrete time steps from DVGW GW 321:
| Duration | Time factor f_t | Explanation |
|---|---|---|
| ≤ 30 min | 1.00 | Baseline |
| > 30 min – 20 h | 0.90 | Step reduction −10 % per DVGW GW 321 |
| > 20 h | 0.75 | Step reduction −25% per DVGW GW 321 |
Practical tip: For most standard pull-ins (up to approx. OD 400), select “≤ 30 min”. Longer durations are only realistic for very long bores (> 500 m) or large diameters.
Pipe Wall Temperature (Pro)
Temperatures outside 20–40 °C reduce the allowable stress. In summer construction conditions, pipe wall temperature can quickly reach 30–35 °C.
Bending Reduction Factor f_b (Pro)
Accounts for stress caused by curves in the bore path. Options:
- Manual entry: Typical values 0.80–0.95.
- Automatic from bend radius: In Pro mode, the planned radius R can be entered. Bending stress is then deducted directly from the available tensile stress:
$$\sigma_b = \frac{E_{short} \cdot d_e}{2000 \cdot R}$$
The remaining tensile stress is $\sigma_{eff} = \max(0, \sigma_{ans} f_t f_T / S - \sigma_b)$.
Calculation Model
The allowable pull force is determined in two steps:
1. Ring cross-sectional area:
$$A = \pi \cdot s \cdot (d_e - s)$$
2. Allowable pull force without a radius:
$$F_{zul} = \frac{A \cdot \sigma_{ans} \cdot f_t \cdot f_T \cdot f_b}{1000 \cdot S}$$
With a radius, the calculator instead uses:
$$F_{zul} = \frac{A}{1000} \cdot \max\left(0, \frac{\sigma_{ans} f_t f_T}{S} - \sigma_b\right)$$
| Symbol | Meaning | Unit |
|---|---|---|
| A | Pipe wall cross-sectional area | mm² |
| σ_ans | Short-term tensile stress of the PE material | N/mm² |
| S | Safety factor | – |
| f_t | Time reduction factor (pull duration) | – |
| f_T | Temperature reduction factor | – |
| f_b | Bending reduction factor | – |
Interpreting Results
The result is displayed as a range with three levels:
- 🟢 Conservative (S = 1.50): Capacity value with the largest internal reserve in the displayed planning band.
- 🟢 Recommended (S = 1.25): Internal planning value with an additional safety factor; GW 321 itself does not specify this factor.
- 🟡 Optimistic (S = 1.00): Theoretical maximum – for comparison only, not a design value.
Impact factor chips (Pro): Colored indicator chips show which reductions are active and how much they influence the result.
Notes & Limitations
- The result is the allowable tensile capacity of the pipe only, not required pullback force or rig capacity.
- Not considered: Borehole friction, hydrokinetic loads, reaming, cutting, breakaway and stationary loads, buoyancy, pipe string weight in the bore and external-pressure collapse.
- For SDR > 17, a project-specific stability and collapse check is particularly important.
- Project-specific approvals, manufacturer data and site-specific conditions remain mandatory.
- Reference: DVGW GW 321 (10/2003), Annex A, for the implemented time reductions and allowable pipe loading.
All data provided without warranty. Full disclaimer