Single Use Compensator Analysis

Read about START-PROF pipe stress analysis software

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Single Use Compensators allows to pre-stretch a buried pipeline. Pre-stretching is done by pre-heating the pipeline up to the temperature half of temperature range in operating mode. After initializing Single Use Compensators and welding the edges of their restraints, the pipeline becomes a continuous structure. Therefore, these expansion joints are used only once. Ideally, Single Use Compensators allow the laying of a pipeline as long straight sections, where thermal deformation from heating and cooling is compensated for by axial stress of compression/expansion of pipe material.

Start-Elements allows approximate modeling of spacing between Single Use Compensators and locking temperature.

Therefore, START-PROF analyses are more accurate and precise than Start-Elements, so Start-Elements should be used only for preliminary analyses. Final safety checks should be done with START-PROF.

If Single Use Compensator use conditions are not met, an error message "Single Use Compensators cannot be inserted. Temperature difference is too high" will be displayed:



Sr - stress range from hot to cold temperature difference,

Sa - allowable stress. For CJJ/T 81-2013 code Sa = min(3*Sh, Ss),

Sh - allowable hot stress,

Ss - allowable local wall stability stress per EN 13941 p.

If this error occurs  - try to increase the wall thickness to increase Ss value or use another steel with higher Sh value.

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.

Input data



External diameter, Dа

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

Cold temperature

Average wall (metal) temperature after cooling.

Operation temperature

Operation temperature in operation state. More...

Depth, Z

Depth (distance from soil surface to pipe axis)

Uniform pipe weight

Piping 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)

Operation pressure, P

Operation pressure in operation state. Set for all standards except SNIP 2.05.06-85. More...

Steel grade

Pipe material from the materials database

Weld pressure quality factor

Set based on standards. Can be calculated automatically by pressing . More...

Insulation type

Insulation type: Armopenobeton, polymer, polyurethane, other.


After analysis, the following output is displayed



Spacing  Lmax

Maximum spacing between Single Use Compensators based on strength requirements

Locking temperature

Temperature at which expansion joints are locked

Menu Access

Expansion joints > Single use. Analysis of Lmax and Locking Temperature