Dear all,
i am new comer for ceaser,can u tell me how can calculate the nozzle displacement with some example.......


with regards,
narayanan

Hello Narayanan,

Compile the required information:

1. Dimensions from the vessel or pump or whatever ANCHOR to the point of attachment of the pipe to the nozzle of interest. Note that most horizontal vessels will be "anchored" on one support while the other support(s) is(are) allowed to move to accommodate expansion/contraction.

2. The materials between the anchor and the nozzle and their coefficients of expansion/contraction (the coefficients of expansion/contraction will vary with changes in material).

3. The temperature changes of the materials between the anchor and the nozzle (from ambient or "installed" temperature to the operating temperature). For a tall process vessel there may be (or may not be) several "zones" with differing temperatures. If the temperature "profile" differs you will have to model to accommodate the varying temperatures.

Calculate;

The coefficient of expansion/contraction times the temperature change times the length in each direction will give you the movement from the "anchor" to the point of pipe attachment at the nozzle of interest.

It may be of some value to you to go here:

http://www.pipingdesigners.com/downloads/process%20plant%20piping%20overview.pdf

......and download Vince Carucci's piping design class notes.

Good luck.

Regards, John.

Post deleted by MGR

Narayanan

You need help. Badly. Please talk to whoever has assigned you to this task and see what resources are available in your office. The problem you ar trying to solve, and your apparent grasp of the subject, do not seem to be something that can be handled competently in this venue.

You have given nowhere near enough information to answer the question you have asked. And much of the information you have given is irrelevant to the problem.

Typically, a pump is assumed to be fixed about the center of the bearing nearest the fixed support. (Normally, the support at one end of the pump is bolted to the baseplate and the support at the other end is allowed to slide on a lubricated or PTFE slide plate.)

In order to calculate movement of a nozzle, you need to know the dimensions (X, Y, and Z) from the centerline of the pump shaft at the center of the bearing to the centerline of the nozzle you are concerned with. Most manufacturers design their pump support legs so that they are not much affected by the temperature of the process fluid, so that it is usually incorrect to assume that the pump expands from its baseplate as though all the metal between the baseplate and the nozzle was at a uniform elevated temperature.

Then, you need to know the material of the pump casing. This is often the same as the pipe material (although A-53B is a pipe grade and your pump vendor's engineer will probably get a glazed look on his face if you mention that spec to him) but I have seen many pumps with cast iron casings, or bronze casings, or other materials, bolted up to A-106B or A-53B pipe.

Then you need to know the average metal temperature of the pump casing. This may (or may not!) be the same as the process temperature for the fluid in your pipe. For instance, if you have a pump with the inlet conditions of 1 psig and 75 deg F, and discharge conditions of 350 psig and 160 deg F, the average pump casing temperature will be neither 75 F nor 160 F, but something in between.

Finally, you are ready to calculate the thermal growth as dX = alpha * dT * (X2-X1), dY = alpha * dT * (Y2-Y1), and dZ = alpha * dT * (Z2-Z1). Make suer you use the appropriate alpha for the pump casing material. And signs are important!

Much of this information will probably be unavailable to you. For the casing metal temperature, it may be conservative to assume the highest temperature of any process line. Then again, it may not be. And you don't sound like you have the necessary experience to tell the difference.

Good luck if you try to do this anyway. It appears that you will need it.

Narayanan,

To keep things simple, why don't you ask the vendor for the nozzle displacements?

I fully agree with Craig that you do not have the necessary experience to properly do this computation and hence it is prudent on your part to ask the vendor for this information.WRC Bulletin 449 also recommends the same.

Regards

Hi,
thank u to all for ur brief explanation......



regards

MGR