Hello There,
I,ve search and read through many answer in this forum about Flexible hose,flexible connector and flexible joint....the conclusion that i got is that we don't have to model it in CAESAR II.
But i have this situation,before my pump suction and discherge nozzle there are Flexible Joint (or we call it Flexible pump connector) and also a PRV (Pressure relief valve). I have to check the Nozzle load in suction and discharge and also have to check the force and moment for PRV case. the problem and my answer is the same how about the Flexible Joint?if i don't model it i will not have a right approriate results. I try to model it from the suction nozzle to the flexible jint end, and stop there, the discherge is also the same, only that i connect the PRV line from discharge to suction with Sockolet. For you to understand my description, i attach the Picture here....
Hope that any of you can help me to give the right way to model this situation for Nozzle load check and PRV Load check.
Thanks.

Hi Dylan

Caesar don’t have provision to model flexible hose.
Making two separate model & considering both end of hose as free point is an option.

If hose is braided one it take care of pressure thrust itself, if non braided one thrust force (Pressure*area) have to add with both the Caesar model & have to make proper support accordingly.

Regards

Habib

Dylan, I'm not seen an attachment to open.

We need to be careful with our language. At least as I'm familiar with them, a generic use of "flexible connector" or "flexible joint" typically refers to a bellows type expansion joint. Those can, and MUST, be accounted for in a Caesar model, particularly of a pump system.

A flexible hose is something different. It's true a hose cannot be modeled in Caesar. I can't say I've ever seen a hose used for a pump, unless it was something very small, like a 1" chemical injection pump.

Im sorry yesterday i failed sEveral times to attach the model. Here i attach the CAESAR model and the section of my CAD drawing.
In the model you can see that for this system (Pipe 6" Sch. 40, A53 Gr B, Design Temp=48 Celcius, Amb Temp=38 Celcius, Max Suction Pressure=5.31 bar, Max. Discharge Pressure=7 Bar)i modell it only until the flexible hose and add support Z and Y after it. Actually there are Basket strainer 6 inch and gate valve 6 inch after the flexible hose at suction, and also there are check valve 6" and gate valve 6" after the flexible hose at discharge side. This is what i'm thinking: that if i modelling like this it means that the dead weight of basket strainer and gate valve and others before the flex. hose is taken care by the flexible hose itself, doesn't it? and the same at discharge the dead weight of chechk valve, gate valve and others after flex. hose is teken care by the flexible hose it self. So is it right the way i'm moelling this in case i want to check the nozzle load at suction and discharge? and also i want to check the Load during the opereation of the PRV attach at discharge side. (The PRV is in size of 1 inch).
Please enlighten me....
Thanks..

Hi Dylan
Pump nozzle will take the flange, elbow,pipe plus half the hose weight along with fluid weight inside.
As Edward mention hose is not generally used in pump suction & discharge nozzle.
For intermediate service line ( Loading & unloading), for tank settlement flexible hose generally used.
You may use untied bellow at pump suction & tied bellow at pump discharge nozzle unless your client want flexible hose as shown in attached drawings.

Regards

Habib

Yes, i have explained my client about the use of flex. Hose in pump line, but my client insist to use this flex. Hose, because their have used it for many years in their other plant n no problem with it. my question still is it right the way i'm modelling this system for nozzle load check n PRV check? Or should i modelling it with basket strainer n valve too?

Hi Dylan

You should not model until first support of suction & discharge line rather should model until half of flexible hose. Make that hose point as free ( No support). All the load in this model will be taken care of pump nozzle ( compare with allowable)

If After the hose line is stress critical, you need to make separate stress calculation for that.


Regards

Habib

OK, shr, it means i only put half of the hose weight in the model, with this model too i can check the PRV case, don't i?
About this hose why can't we use expansion joint input, and give the Bending and axial stifness, coz hose tendency to move in lateral, and i know the difference with ex. joint that hose not give any pressure thrust like expansion joint.so why we haved to model it as a half rigid here? can you explain to me so i can understand what i'm doing here?
Thanks very much for your explanation.

Regards

T. Syahdilan

Hi Dylan

1) Yes you have to check PRV case also. You may put conventional support for PRV discharge line.
2) Expansion bellow act differently than flexible hose. Bellow work like a pipe with much less stiffness property in each degree of freedom. If you use hose with long length you can change the direction unlike bellow. Hose do not transmit force & moment of piping from one side to other side like bellow (or like say small pipe piece). That’s why bellow should be included in piping model but not the flexible hose.
3) In any item with pressure there will be pressure thrust. For pipe piece it absorbed pressure thrust by longitudinal stress. Tied bellow absorbed by tie rod. Untied bellow gives external pressure thrust. Flexible hose if it is non braided one it create pressure thrust like untied bellow. If flexible hose is a braided one it can absorbed pressure by itself.
4) Half hose need to model to take half of it’s weight. Rest half weight will be transfer to other side support ( Other stress calculation)

Regards
Habib

OK Shr, thank you very much for your explanation and answer, i really appreciate it,i can clearly see what i'm doing now. And hope the best for people like you who like to share knowledge to other. thanks.

Regards

T. Syahdilan