Allowable load fail in moment in that attachment.

Allowable load for 8”

Fx=6060, Mx= 8075
Fy=7425, My= 5710
Fz=7425, Mz = 5710

As per analysis at node 330 (8”)

Fx=2371, Mx=-9036
Fy=6187, My= -1214
Fz=7118, Mz = 2996

In that case how should arrest the moment in –RX?

Hi Kevin,

From the model my assumption is that the reason of increase in the moment in X-direction will be the arrengment you have between node number 64 to 130.
The distance is not clear from the graphics. Can you attached one more copy with the distance mention clearly? The arrengment looks so stiff that there is no any pipe piece to take care of the movement due to thermal expansion near the nozzle . attach the distance also.

Regards,
RK

Please find the attachment. Shall I give +RX on node320.if i give, moment will be allowable.

HI Kevin,

I could not see node 320. But is it possible to make some routine change? I mean this conncetion to nozzle looks so stiff that there is no any chance of free expansion of pipe.

About the Rx support yes you can give that, but befor that you must know how you will built this support.

Hi kevin
It is not possible to comment just with graphix.

Just to deal with moment problem. In one direction moment could be high because high force in another perpendicular either direction. Long unsupported portion or using a spring instead of rigid support sometimes leads to increase in moment.

For your case I guess temperature is positive, you should not put Y guide support at node 63, that may increase Y force at node 330 & creat moment in X direction. Even if you like a guide there you can put it with gap.
At node 90 also I do not think Y direction support is quite good.

If you can increase leg of each branch that also improve piping flexibility.

Please just do not try match the allowable value somehow, try to understand effect of each support how they are affecting the result.
When I work with a critical system I make number of caesar run with different combination of support to understand the system behavior properly. Once it is clear it will be very easy to find a solution.

Please do not take my comments otherwise.


Regards

Habib

Looking at the graphic it does not appear you have considered any equipment growth. At sensitive equipment in order to have accurate loadings that accurate Nozzle Displacements caused by equipment growth are considered.

Hello Kavin,

Habib's suggestions are excellent. He has done this before.

Quite often, how a piping system behaves in response to forces and moments is counter-intuitive. I find it useful to look at the deflected shape of the piping system. This helps visualize what is happening and what you need to do to reduce your forces and / or moments acting on equipment connections or tank nozzles. When viewing the deflected shape, one can sometimes notice a piping configuration that tends to behave in a teeter-tottering manner.

This is consistent with Habib's suggestion " .... try to understand ..."

Regards,

Pat

Hi Habib,

Thanks for your valuable information. i got it. i have one more doubt any standard support for arresting moment in rx, ry, rz.

Hi kavin

You can not make support that only arrest rx, ry or rz.
Make use of guide/axial stop to reduce moment.


Habib

The stress on the attachment is a result from all forces an moments.
If one moment (Mx > as allowabled Mx) , then mean that not stress is to high, because the moment My and Mz < My,z allowabled.

hi ohiiger,
i can't get u.please explain in brief.

Your calculated forces are < as your allowabled forces.
So we can look only to the moments.
If you attachment on node 111 (Plot), then Mx a torsion moment.
My and Mz are bending moments.
Then your comparison stress must be lower as allowable stress.

Hi kavin
What ohliger is trying to explain, even if one directional force or one directional moment exceed the corresponding allowable still we can accept that if resultant calculated force is less that resultant force allowable & calculated resultant moment is less that resultant moment allowable.

This concept sometime we may use but it will not be accepted for all kind of equipment & may not be accepted for all vendor/Client.

Regards

Habib

The stress, the displacement and the function are important for a engineer
say this your vendor/Client.

hi Stress Engineer

In 16" line 1500Kpa at 240degC but length of the pipe is 2000mm. whether it considered for analysis or not.If i do analysis it will fail in allowable nozzle load.

Shabeer,hi


•Did you check the support lift-off?
•Did you incorporate the thermal growth from the equipment? You may model your equipment in Caesar and have a connecting node to your piping.
•Please continue model the nozzle piece maybe 300mm or less up to the vessel interconnection, and take the schedule from the vendor drawing especially that you have a tight layout.
•Try to remove the guide at node 63.
•At node 45, your taking support from the equipment please verify if you have incorporated the displacements of your equipment. Lastly, check the orientation of your guide.

Have a nice day.