Allowable Stress Indicator / Pipe Restrained Status - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

The B31.4,B31.8, and ISO-14692 2017 codes recognize restrained and unrestrained conditions.

Restrained and unrestrained options define the stress equations used but do not affect the forces, moments, and displacements calculated for the pipe element. For example, if you select Restrained Pipeline when the pipe element is not restrained, the software uses restrained stress equations even though they do not represent the tur state of the pipe element. We recommend that you use the CAESAR II Determines option, which allows the software to make stress equation selections based on the actual operating conditions.

For B31.4, select an indicator to define the stress equations and allowable values used by the software:

Restrained Pipeline

Specifies fully restrained pipe, which is locked in position. The pipe is fully restrained beyond the virtual anchoring at bearing points (such as elbows and tees). Axial stress is defined without the use of bending moment.

Unrestrained Pipeline

Specifies all piping that is not fully restrained. Unrestrained pipe is free to displace laterally and to strain axially. Stress calculation is dominated by bending moment.

CAESAR II Determines

Specifies that the software selects the stress equations based on the calculated axial load in the piping system. The software applies the fully restrained stress calculation when the axial pipe load is within 2.5% of the limiting load, meaning the pipe is held in place by the restraint of the soil. The software applies the unrestrained stress calculations when the axial load is different from the limiting load by more than 2.5%.

The limiting load is the force needed to fully restrain the pipe's axial growth. The axial growth is due to the thermal expansion and the pressure expansion calculated when a Bourdon Pressure option is selected in the Configuration Editor or in Special Execution Parameters.

For information on the code equations used, see B31.4 and B31.4 Chapter XI.

You typically use this option with the Underground Pipe Modeler or when modeling soil/pipe interaction using restraints. For more information, see Underground Pipe Modeler.

Inland Riser/Platform

Specifies riser and platform piping on inland navigable waters and instructs the software to select different sets of allowable values as defined in the Table 403.3.1-1.

For B31.4 Ch XI, B31.8, and ISO 14692 2017, select one of the following indicators:

Restrained Pipeline

Specifies fully restrained pipe, which is locked in position. The pipe is fully restrained beyond the virtual anchoring at bearing points (such as elbows and tees). Axial stress is defined without the use of bending moment.

Unrestrained Pipeline

Specifies all piping that is not fully restrained. Unrestrained pipe is free to displace laterally and to strain axially. Stress calculation is dominated by bending moment.

CAESAR II Determines

Specifies that the software selects the stress equations based on the calculated axial load in the piping system. The software applies the fully restrained stress calculation when the axial pipe load is within 2.5% of the limiting load, meaning the pipe is held in place by the restraint of the soil. The software applies the unrestrained stress calculations when the axial load is different from the limiting load by more than 2.5%.

The limiting load is the force needed to fully restrain the pipe's axial growth. The axial growth is due to the thermal expansion and the pressure expansion calculated when a Bourdon Pressure option is selected in the Configuration Editor or in Special Execution Parameters.

For information on the code equations used, see B31.4 and B31.4 Chapter XI.

You typically use this option with the Underground Pipe Modeler or when modeling soil/pipe interaction using restraints. For more information, see Underground Pipe Modeler.

Design Factor displays on the Allowables tab of List.