Axial force Time history analysis


In Annex 1,

I showed the formula from API520, where the force resulting from the opening of the safety valve, consisting of the dynamic and static forces, is determined.
The Autopipe program, in the tab Loads>Fluid transient determines the force value from the dynamic effect (Annex 2).

When performing a Timehistory analysis, the occasional stress program adds the flow loads and gives results in the form of pipe stresses.
I would like to ask whether the static force component of the pressure and the active surface of the pipeline should be added in each bend of the pipeline section (similarly to expension joints when entering difference betwen the effective area of the expansion joints and the cross section of pipe )?
Thank you in advance for your quick reply.

  • Hi Grzegorz,

    From the mention of API 520, I assume you are asking about a pressure relief valve.  In this case, please take a look at our Steam Relief utility (Loads Ribbon) available that will automatically calculate the thrust load from some user inputs of the pressure relief/vent arrangement.  AutoPIPE applies this thrust load as a forcing function to the model by automatically creating the Time History Profile and Time History Locations files.

    The Fluid Transient utility that you are mentioning here can also be used for pressure relief valves to take into consideration the acoustic shocks in the pipeline due to the rapid opening and closing of the valve.  This calculated force is based on Joukowsky's Equation to calculate the pressure rise that will occur with the change in velocity of the contents of the pipe.  This pressure rise is then multiplied by the area of the pipe section prior to the bend where the force is being applied.  Using this utility automatically calculates the forcing function to be applied at each change in direction in the pipeline, and creates the Time History Profile and Time History Location files for the user.

    There are training classes for both of these available on the LEARNserver:

    I hope this helps.

    Jessica Alegre

    This is a test