# 'Globe valve - thermal shock analysis' simulation project by ahmedhussain18

#1

I created a new simulation project called 'Globe valve - thermal shock analysis':

In this project, a thermal shock analysis of a globe valve is performed.

More of my public projects can be found here.

#2

## Description

Despite the multiple advances that have been made in the plumbing field, there is always room for improvement and optimization. For instance, let us consider a regular pipeline assembly with shutoff valves. Essentially, a shutoff valve controls (obstructs, mediates or allows) the flow of water through it. One of the most common shut of valves is the Globe Valve.

Globe valves

Oftentimes, there is hot fluid flowing through these valves, especially in heating systems such as a geyser or a space heater. Sudden exposure to these high temperatures may lead to thermal shock. By definition, a material undergoes a thermal shock when it is subject to a thermal gradient, which causes it to expand unevenly.

Conducting a Thermal Analysis for a specific design and material helps determine its behaviour under these circumstances. Through the analysis results, we can determine a new design or choose another material for a specific application.

## Project Goals

In construction, a globe valve consists of a cylindrical plug (with the axis perpendicular to the direction of water flow) suspended by a stem, which perfectly fits in between a stationary ring seat. The stem connects the plug (disk-shaped) to the valve handle as can be seen in the image above. The plug can move only in the direction perpendicular to the flow, varying the space left out for the water to pass through, thereby regulating the flow of the valve.

With the help of the SimScale platform, we shall simulate the flow of hot water through a globe valve, trying to comprehend the various processes occurring before, during and after the passage of the water through the valve.

We carry out a thermal shock analysis of a globe valve in order to test its behaviour. The analysis is performed based on the findings by Mathieu, J. P.. Based on these findings, the application of the pressure and temperature is on the extreme sides so that we can observe the effect of hot and cold thermal shock on the globe valve.

## Geometry

The geometry was provided by Mariusz Stanosz from GrabCAD and is shown in the figure below:

## Meshes

Due to the symmetry, only half of the geometry is considered for the analysis. This saves both the computation time and the result size. Furthermore, the geometry is simplified in order to easily be able to achieve a good mesh. The modified geometry used for the analysis is shown in the figure below.

The geometry was meshed using parametrized tetrahedralization with moderate fineness. The mesh is shown in the figure below.

## Simulations

A Transient, static nonlinear, uncoupled thermomechanical analysis is selected as the analysis type. All the top and side bolts including the stoppers and glant are bonded to the outer surfaces, whereas the stem bolt and the spindle are given a sliding contact against the desired surfaces.

On the other hand, Augmented Lagrange physical contact was defined between body, bonnet, and pipe joints. Symmetry is applied and the pipes are constrained via a remote displacement boundary condition. Outer surfaces are given a convection coefficient of 25 W/m2K at 307.15 K (35 oC).

Initially, the tightening of bolts is performed by setting their Reference temperature to 373.15 K (100 oC) in material parameters. By doing this, the pre-stressing is introduced due to sudden shrinkage of the bolts. After the tightening of the bolts, a pressure of 6 MPa is applied to the internal surfaces and then kept constant. Next, the hot thermal shock of 573.15 K (300 oC) is applied in 10 sec on the internal surfaces and then kept constant until the thermal equilibrium is reached. After thermal equilibrium is attained, a cold shock of 307.15 K (35 oC) was applied in another 10 sec and then kept constant until the thermal equilibrium is reached.

The analysis is run for total simulation interval of 468 sec (7.8 min) on 32 cores and takes around 323 min to complete.

## Results and Conclusions

First figure below shows the stresses produced due to initial tightening of the bolts.

Moreover, the figures below show the temperature and stress distribution at different intervals of interest.

The reaction forces produced on the bolt faces are an interesting observation. Therefore, the reaction force values are requested on one of the inner faces of the top and side bolts under Result Control. The bolts are numbered in the fashion given below (upper shows top bolts whereas lower shows side bolts).

The graph below shows the reaction forces over time on side bolts.

The graph below shows the reaction forces over time on top bolts.

The graphs above are trimmed to thermal shock phases only. Therefore, one is not able to see the initial phase of bolt tightening and pressure application, which are of little importance. Interestingly, there is a fluctuation of forces in cold shock region in second graph. This could be due to several reasons; one of which could be that from the initial tightening of top bolts to the completion of the analysis, the top physical contact remained opened, probably due to design defects. The figure below shows the contact distance in the y-direction of the top physical contact at different intervals.

Finally, figures below show the animations of full model and the upper contact region respectively.

Conclusions:

At the end of the analysis, it is safe to conclude that the performance of this globe valve can be further improved under these extreme conditions by following some improvements as mentioned below:

1. The geometry can be modified in order to restrain the opening of the bonnet. For example, the diameter of the bonnet and body holes can be decreased in order to have more area under bolts so that the tightening closes the bonnet and body well.

2. The thermal properties of the material can be changed so that it has a smaller thermal expansion factor. This will reduce the expansion of valve under extreme conditions.

3. A seal can be introduced between a bonnet and body so that after tightening, the bolt seals will compress and thus, restrain the opening of the valve after the pressure and thermal shock are applied.

## References

Mathieu, J. P., Rit, J. F., et al. “Thermal Shock Effects Modeling On A Globe Valve Body-Bonnet Bolted Flange Joint” arXiv preprint arXiv:1202.5125 (2012).

A collection of FEA resources
#3

Awesome project @ahmedhussain18! Also great result processing!

#4

Thanks @rszoeke!

#5

Very impressive, @ahmedhussain18!

#6

p.mohafezatkar@gmail.com
Hello. It is possible that you Twilight engineer the simulation geometry and mesh to provide me with this?
thank you

#7

p.mohafezatkar@gmail.com

#8

Hey @pmohafezatkar!

This project is a community project and open for everyone to make a copy or use it for his/her simulation. Please feel free to make a copy of it

Best,

• Ahmed

#9

Nicely done, very thourough and well-documented. Impressive results.

#10

Thanks @dengerer!