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LESSONS & TOPICS

Calculate Initial Movement

Calculate Initial Movement

For piping system connected to equipment such as pumps, compressors, turbine, tank, it is imperative to calculate the Initial Movement of the Nozzle using Equipment operating temeprature. This is mainly due to our stress calcualtion will be started on the point where pipe flanges conected to nozzle equipment, and this point will be treated as Anchor with Displacement, as sample shown below for pump.

 

In order to calculate the Nozzle displacement, we will use formula which was included on seperate course: Introduction to Piping Stress, and for the sake of this course will be shown below:

Where:
w = the distance from center of the pump anchor support to the center of nozzle (lateral)
e = Coefficient of Thermal Expansion of the pump at Temperature.
The result could be positive or negative depend on the agreed axis .
As we know that, for Hot Temperature, nozzle will expand away from the center of pump support, and with being connected to the pipe, which also has their won thermal expansion, will create a forces and moments toward the pump nozzle. Those laods need to be checked against pump allowable laod.
 

Next, we will see the case with pipe support on the vessel, with temperature operating of 200oC, coming out from the nozzle at elevation of EL. 12000 mm, and making route as below with some expansion loop to absorb the thermal expansion of the pipe, as shown below.

First, we calculate the initial movement of Nozzle A. Since the pipe will be supported at Point B, then we also need to calculate the movement of Pipe support point B, either 1) by multiplying the distance from the bottom (fix point) to the support location with thermal expansion of equipment at Operating Temperature, or 2) by substracting Movement of Nozzle A with the result of multiplying the distance between Nozzle A nad POint B with Thermal expansion.