LITTLE P.ENG. FOR ENGINEERING CONSULTANCY SERVICES

Cold spring is the process of offsetting (or pre-loading) the piping system with displacement loads (usually accomplished by cutting short or long the pipe runs between two anchors) for the purpose of reducing the absolute expansion load on the system. Cold spring is used to: hasten the thermal shakedown of the system in fewer operating cycles reduce the magnitude of loads on equipment and restraints, since often, only a single application of a large load is sufficient to dam

As discussed elsewhere in these seminar notes, CNODES (short for connecting nodes) are used with a restraint whenever a point in the piping system is retrained against another point in the system. The CNODE point may be physically on a vessel, a steel structure, or another piece of pipe; or it may be a fictitious node which can be used to model a wide range of system behaviors, such as settlement. For example, pipe on pipe supports can only be modeled using CNODES. One exampl

Elements of structural steel members may be incorporated into the model of the piping system through the use of the structural steel modeler. These elements may vary from a single member (such as a saddle, welded to the pipe), to a complete restraint structure, to a complete model of the building steel. The steel may be modeled in order to include the stiffness of the structure in the analysis, or in order to calculate the loads on the steel for stress analysis of these membe

In Section 2.3.3 of these seminar notes the significant effect that restraint stiffnesses may have on the piping system was described. Assuming restraints are rigid (when they are far from rigid) can lead to grossly conservative designs, possibly resulting in the unnecessary modification of the system. However, assuming that restraints are rigid cannot always be counted on to produce conservative solutions in a complex piping system, either. It is therefore often necessary to

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