HI ALL
I AM NEW FOR CAESAR 5.1
IN ANAYSIS,WHY SHOULD WE GIVE DISPLACEMENT IN PIPE?
WHEN PIPE CONNECTED IN VESSEL NOZZLE THAT REGION WILL BE AN RIGID.IT MEANS NO MOVEMENT IN THAT NODE.CAN I SUGGEST TO GIVE ANCOR INSTEAD OF DISPLACEMENT. HOW I CAN CHECK ANALYSIS WILL BE CORRECT OR NOT.

IN WHAT BASIS ANALYSIS RESULT WILL BE CHECKED.
HOW I GIVE SUPPORT BASED ON WHAT?

WIHT REGARDS
SRINI

I guess you are new to stress analysis as well. Have you considered that the vessel your pipe is connected to might expand or contract ?

Talk to your lead engineer. You need help.

hi moverz
thanks for suggestion....
why should give displcement in nozzle point of the pipe?
when i give more support to that region like rx, ry y?
how its possible to model?

Hi,

Equipments undergo thermal expansion once subjected to heat, consequently nozzle connection points on equipments will have displacements.

Use the Caesar II help function to know more about modelling?




Best wishes,

Shabeer,

As an example, consider a tower 50m tall, running at 300 deg. C. The top nozzle will expand around 180mm upward. Are you seriously thinking that the nozzle could be modelled in a stress calculation simply as an anchor ?

Hi shabeer,

I suggest you read a book of material science first and/or machine design books. There you will find the effect of loading in your material and the modes of failure. For piping system consider a simple cantilever beam where at the end is fix and the other end is free. Now exerting effort on the free end will cause a deflection(DISPLACEMENT)..... That means, too much force applied will cause the material to yield and probably fail.

http://en.wikipedia.org/wiki/Cantilever_beam

Regards!

Hi Shabeer,

The effect of the equipment nozzle movement on your piping system will depend on the extent of nozzle movement which again depends on factors like temp. of equipment (causing expansion of nozzle), vibration, etc.
Talk to your lead engineer. If the equipment is a cold one, you can carry out the analysis with nozzle as anchor "only to get preliminary loading". Then, as the nozzle movement information comes from the equipment vendor in future, you can incorporate the same in your analysis to get the exact results.
For vibrating(rotary) or high temp. equipments, nozzle displacemnts are critical and must be certainly incorporated.

Regards,
ASA

think about railroad in daylight, it may help you to imagine how vessel is grown up due to thermal effect

Dear Shaber,

The concept of "FREE BODY DIAGRAM" is quite good answer for you question. When we anlyzed a selected system then all Forces, Moments, Displacements ect directed to it comes from outside system and has effect shall be applied in analysis/calculation.

I am busy with 12 lines where design temperature is around 100 C but one end moves 170 mm down and about 5 and 40 mm horizontal. Thermal expansion of the pipe is minimal compared to these forced movements. To leave them out I would not include 48 VJ flange adaptors into the design and lines would fail when started up.

Just a warning. If you give displacements X, Y, and Z and leave the remaining rotations blank you will have funny results because you are telling CAESAR II that the pipe can rotate freely.

Many stress engineers like to put ANC connected to CNode, which has displacements.

... or alternatively, specify the XYZ displacements and then specify zero for the RX, RY, and RZ rotations.

Shabeer,
Another thing, check if analysis required vessel settlement to be considered, which also to be provided using displacement option.

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Naren