Dears,

As we know all densities on buried pipe elements are zeroed to simulate the contentious support of pipe weight.
Also if we have a buried valve, Caesar II will zero the rigid weight in buried model.
Is it required to enter the rigid weight in buried model again or Caesar II will be considered the weight of rigid element during generation of restraint ultimate loads and stiffnesses?

Thanks

I guess you have a underground cavity for the valve, and do not think you cover the valve itself with soil. Therefore the valve cavity needs to be not buried in your model. So you can provide the weight of the valve and the pipe in that cavity.

Hi Demir,

No,In this case we have not valve pit and the extended stem valve (42",Weight=21530Kg) is buried.
And i don't know why Ceasar II remove the rigid weight and i have to enter it again in buried model or not?
As I searched in forum i couldn't find similar post in this regard.

There is a condensed mass in a small area, this will cause settlement in case there is no proper bearing foundation application under the valve which will equalise the pipe and valve behaviour in terms of settlement.
Additionally, the valve will act almost as an axial anchor due the the volume (diameter) against the pipe. How are you going to model this axial restraining and the settlement actions at around the valve?
How about the extended stem, don't you think there will be some axial displacement on the line with operation temperature? The stem will be held by the soil and may cause shear/crack at around the connection to the valve.

42" valve is not a small valve, it may require maintenance during operation? Without an underground cavity (room) you cannot make adequate maintenance.

If you put them all together the room option which is used by major engineering companies becomes reasonable (I understand the underground room has some restriction to manage/enter but still is the most viable option), otherwise this needs to be discussed by a team of engineers which includes civil engineer and the operator.

After you gave this discussion with them you will almost know what you are going to do.

Under the valve will be a concrete block which has been designed by civil.
The design is ok, my question is about CAESAR II:

Is it required to enter the rigid weight in buried model again or Caesar II will be considered the weight of rigid element during generation of restraint ultimate loads and stiffnesses?

So pipe and valve loading will be taken by the soil, and civil engineer will guarantee that there will not be any differential settlement under the concentrated load on the soil(it is hard to believe but under certain condition this may be achievable). In this case, if you model the valve buried, CAESAR II will not considered the valve mass in the analysis. Therefore you do not need to enter the valve weight since it is going to be useless in the buried model.

My question is; How you are going to model the valve axial restraining action in your model due to valve's large diameter than the pipe itself, and it is substantial?

Sometimes you can introduce the mass of the valve as load to be able to simulate the behaviour of the pipe and valve together in the valve local area. In this scenario you need to produce sufficient number of nodes on the above ground model on both sides of the valve, and for the valve. After getting the buried model the nodes introduce the load on the valve node(s).

In this case you may be able to see the valve mass effect in that area. However, introducing the concrete block will have an impact in this area and the result will not be reliable. Additionally the concrete block will have big mass that the soil again will be effected by additional settlement (Long term settlement.

I wish you and the team good luck. It is not a simple task to solve with all those factors above and probably some others. I hope the decision makers know what they are doing.

I keep forgetting to ask the installation and the operating temperatures of the pipeline. Can you please inform us about them for the sake of the discussion.

If you "bury" a run in CAESAR II, that element will have no weight. Also, any restraints added in that buried section will be removed by the program.
If you wish to include a supported, buried valve in your buried pipe analysis, reenter the valve weight and the vertical restraints in the buried model.
So I believe you can do what you wish but I agree with the several concerns expressed by Ibrahim.

Dear Ibrahim,

Thanks for your replies,
As i informed from civil department,due to nature of soil in this area the major settlement have been done by the first loading and long term settlement is minor.
yes,you are right, it is hard to simulate the valve body and its extended stem and the reaction force of soil but maybe by reentering the weight of valve and actuator and modeling the vertical restraint of valve on concrete block we will be close to real situation due to large weight of valve.

Installation temperature:20 C
Operating temp.: 58 C
Design temp. : 85 C
Design Pressure : 115 Bar