Project Phase

Initiate pipeline design

 

Various options to initialize the shape of the pipeline structure and the related soil- and external support reactions can be selected here.

Design Function Phase

Click to expand/collapseProject Phase: Initial

This is the 'normal' start option, where both the pipeline and surrounding soil and supports are considered to be 'stress-less'.

The remaining options transfer a pipeline pre-deformation from another database, which means that the other pipeline must have the same number of nodes. In general to obtain reasonable results, the element division over the pipeline must be the same as well.

The parent pipeline must be defined in the 'project information' data entry group after selecting one of the options below.

For easy understanding, the pipeline is transferred as a deformed structure, kept in that shape by a set of imaginary, external forces, indicated here for the sake of simplicity as F(i).

Info The remaining options as will be described below are only available if the Phasing (F) module is present.

Click to expand/collapseProject Phase: Continue

This option transfers the pipeline shape in the same way as is the case when in design function 5 the unlock option is used. This means, that the external supports (soil included), specified in this database, are attached to the pipeline at their original 'zero'-deformation points.

In case the support system and the loadings and the pipeline properties are the same as in the database from which the deformation shape is taken, then the transferred shape will be the equilibrium state in the new situation as well.

This equilibrium results because the set of external support reactions F(e) generated in the new situation equals the imaginary set F(i). The facility may be used for an 'intelligent guess' to start a new series of calculations. Or to study the influence of small changes in support or pipeline conditions, which cannot be done with the unlock facility because that facility only allows the loading magnitudes and combination to be altered.

Warning This options is not available in the free Educational version.

Click to expand/collapseProject Phase: Phasing

This option transfers the pipeline shape in the same way as is the case when the 'Continue'-option is applied, however, with the difference that plastic deformations of the external support system are taken into account.

This means, that the external supports (soil included), specified in this database, are attached to the pipeline at such a 'zero'-deformation point, that the local F(i) force is generated only elastically by the new support system. If the new local (soil)support can deliver only a force F(e) < F(i), then the remaining force is treated as a 'disequilibrium'-force.

In case the support system and the loadings and the pipeline properties are the same as in the database from which the deformation shape is taken, then the transferred shape will be the equilibrium state in the new situation as well. However with the difference that the 'zero'-state of the pipeline is not 'stress-less' anymore if the external support system in the new situation is plastically deformed.

The facility may specifically be used for the analysis of a pipeline through a series of consecutive loadings (e.g. cyclic pressure and temperature loadings) taking into account soil hysteresis.

Or in consecutive phases the soil support system may change due to various stages of construction or natural behaviour of the surrounding soil (e.g. moving sand waves).

Warning This options is not available in the free Educational version.

Click to expand/collapseProject Phase: Pre-Displacement

This option transfers the pipeline shape in the same way as is the case when the 'Continue'-option is applied, however, with the difference that in the new situation the pipeline is fixed in its transferred shape.

The external supports (soil included), specified in this database, are attached to the pipeline at their original 'zero'-deformation points.

In case the support system and the loadings and the pipeline properties are the same as in the database from which the deformation shape is taken, then the transferred shape will be the equilibrium state in the new situation too.

If the new local (soil)support can deliver only a force F(e) < F(i), then the remaining force is treated as reaction force from some imaginary external support and reported in the output table SUPREA. The facility may specifically be used for the analysis of a 'composed' pipeline structure for instance as they are sometimes used for hot medium transport. If it is a pipeline consisting of two concentric pipelines (e.g. an inner steel, medium pipeline and an outer plastic, jacket tube), than the outer pipe stressing can be calculated in a new database using the deformation of the original steel pipe. A similar situation may be analysed in case the composed line is a steel-in-steel pipeline. In that case an 'equivalent' pipeline is analysed and the result is transferred to two new databases, representing each pipeline separately.

Warning This options is not available in the free Educational version.


H1003, last changed: 14/09/2016

See also:

Design function 1