dear everyone

Could someone please help me for Thrust force and Reaction force in pump modeling.
Our piping system is connected to cooling water pumps with 38” suction and 36”discharge which are pressurized at 4bar. pressure thurst is Calculated by EJMA STANDARD ASSOCIATION. when I was modeling tie rod expansion joint , the resulting value of caesar program was lager than EJMA value of single expansion joint.
Could anyone tell me to clarify what differences between the resulting value of caesar and Hand calculation of based on EJMA.?
I wish you explain the difference to me in detail.
Detail is provided .
.CAESAR CALCULATION VS Hand calculation for EJMA CODE
Hand calculation for EJMA
FA: 736 N
FS: 26049 N
FP:27792 N

The result .
hand calculation based on EJMA
Main anchor A: 26785 N
Nozzle Flange with Cnode :-1006N
Main anchor C:-26785 N

Caesar calculation
Main anchor A: 29667N
Nozzle Flange with Cnode :26762 N
Main anchor C:26762 N



Any way the resulting value is not within allowable limits as per vendor .
I just mean saying ,I want know why flange with Cnode and Main anchor C Have the same value ??.
In my view , flange with Cnode is related with reaction force . right?
Otherwise now what should I consider ?
if thrust force inserted forcibly in caesar, Where could I have to input anchor node or flange with Cnode connected to expansion joint flange node?

1 equation : effective id *P
2 equation : effective area 4/pi(out diamter^2-indiameter^2)*P
also what kinda thrust force Equation do i have to consider? 1 or 2 ??
i am wondering Flange face with Cnode will be input FS(thrust force plus,minus) forcibly in force and moment table , or considered Reaction force ,? if you have any experience of this issue , plz tell me .
I just dunno wat to do with maself. Plz help me ..

plz help me asap

Hi Joekangmin

I guess you put tied expansion bellow in suction line horizontally in between your pump nozzle & main Anchor.

Now According to EJMA you have to put Main Anchor to take care thrust force for UNTIED expansion bellow. But you are using a tied bellow so Main anchor is not required.

In tied bellow NO axial movement is allowed so when you use tied bellow in between anchor & nozzle point( Another anchor) it act as two anchor in a straight line so you are getting equal & opposite thermal force in both the point..................
Answering your question 1 **********I just mean saying ,I want know why flange with Cnode and Main anchor C Have the same value ??.**************

Answering your question 2 **********Thrust force will be effective id *P

There will be small difference in manual axial thrust force calculation & caesar output axial force because in caesar thermal effect of piping & thrust force jointly give effect on output whereas in manual calculation you are considering only thrust force.


In some company practice people use Anchor support very close to tied expansion bellow & then put pump nozzle. Concept is to isolate total piping system from pump nozzle. You can not justify it by using caesar calculation & moreover it is valid ONLY for cooling water service pump.
If you check thermal displacement between anchor & pump nozzle it will be vary small, tied bellow assembly may absorb this small thermal movement in Practical aspect. In theoretical aspect there will be huge thermal force in both side ( opposite direction) & caesar will reflect the same.

Trust that clarifies.

Regards

Habib

Note: Sometimes you can add ties rods (reccomended) as back-up for your anchor. (just in case your anchor fail)

regards,