Read about START-PROF pipe stress analysis software
1 - Pipeline, 2 - soil surface
Note that increased laying depth and backfill soil density positively effects stability, since the soil keeps the pipe from buckling.
Due to this, overload factors for soil, pipe, insulation and product weight are automatically set as less than unity. If bend radius is increased, critical forces are increased, but also "self-compensation" ability is decreased, which increases equivalent forces. Therefore, exact recommendations for changing the initial bend radius to increase stability cannot be given. A certain middle value must be found by changing various properties and running several test analyses. For more information, see bend stability analysis methods.
Several conditions are checked:
Input data can be copied using the
toolbar
icon and inserted into any other Start-Elements analysis by using the 
toolbar icon in
that file.
Property |
Description |
External diameter, D |
External pipe diameter, D |
Pipe wall thickness, S |
Nominal wall thickness |
External casing diameter, Dc |
External insulation casing diameter. If insulation is absent, set as 0 |
Ambient temperature |
Average wall (metal) temperature at the time when pipe segments become a single joined structure. More... |
Design temperature |
Design temperature. More... |
Depth, Z |
Depth (distance from soil surface to pipe axis) |
Bend radius, ρ |
Element bend radius |
Angle of horizontal slant, φ |
Angle between the plane passing through the bend and the plane passing through the curve peak and perpendicular to the vertical plane |
Turn angle, α |
External angle between straight elements adjoining the bend |
Uniform pipe weight |
Pipeline and adjoining equipment uniform weight. More... |
Uniform insulation weight |
Uniform insulation weight. More... |
Uniform product weight |
Uniform product weight. More... |
Backfill soil number |
Trench soil number, can be selected from the soil database (see appendix 1 below) |
Base soil number |
Base (undisturbed) soil number, can be selected from the soil database. |
Design pressure, P |
Design pressure in operation state. Set for all standards except SNIP 2.05.06-85. More... |
Operation pressure, Pop |
Operation pressure (based on standards). Set when analyzing with SNIP 2.05.06-85. More... |
Steel brand |
Pipe material from the materials database |
Insulation type |
Insulation type: armopenobeton, polymer, polyurethane, other |
After analysis, the maximum value of stability margin K is displayed. Stability conditions are considered to be met if K ≤ 1.
Pipe. Buried > Long-radius Bend Stability