Dear All,

Currently, I am checking the forces and moments in the suction nozzles of Plunger Pump by using CAESAR II. The OEM has been determined the allowable forces and moments acceptable for this pump.

Thru CAESAR, I expected that I can simulate various conditions that probably occur at field that may lead the equipment to fail.

The following is the condition that may exist during installation:

1. Suction Piping and Suction Pump nozzle are perfectly aligned. (CASE 1)
2. Suction Piping and Suction Pump nozzle is misaligned in various degree (CASE 2)


Modeling of Case 1:

On CAESAR, I simulated that the perfectly-aligned-pump as Anchored on the suction piping. It is customary to model the pump as a rigid anchor.
Based on that modeling, I found that even though the pump nozzle is perfectly aligned, its Fz (force which co-linear with Z axis) is exceed the pump manufacturer spec (3518 LB VS 700 LB). I think this happen because of too many supports to the pump suction nozzle.


Modeling of Case 2:

On case 2, I am going to simulate the forces and moments that are applied to the pump when pipe flange in the state of misaligned. This normally happen to the piping which is forced to be aligned by using chain block.

On this case study, I assumed that the suction pipe is misaligned at Z-Axis to 4 mm (0.157”), at X-Axis 6 mm (0.236”), and at Y-Axis 6 mm (0.236”). Instead of modelling this condition as an anchor, I simulate the piping flange as a displaced pipe. The Fz value (3518 LB) is still is the most dominant force among others. Others forces and moments surprisingly is still within the OEM spec. Also the Fz value is still same as it is on Case 1.

Logically, when we pull the piping and put it into aligned by using chain block etc, it will require more moments and forces. It will then transfer them into the pump as nozzle loading. This does not make sense to me.

Is there any other idea how to simulate the state of misallignment?


Yeri

Dear Mr. Yeri can you upload the CAESAR model so i can see it.

thank you

Hi Yeri

First don't try to solve misalignment problem like this. you need to use first support close to pump as adjustable support to make it properly align.
The exercise you are doing is quite good. It will give you feelings how piping system behave under different condition. Input same displacement values with different type of suction pipe routing & compare result. Then you can get good idea about piping behave under different situation that eventually help you to solve practical stress problems.
Good luck.

Regards

Habib

Dear Yeri,

There is could be problem from frictional forces acting on the pump nozzle. This force is along the pipe. If this the case, you may use Teflon plate supports, then 0.1 friction coefficient.

best regards

Rao

Mr Dylan,

Please see the model.