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IPASJ International Journal of Mechanical Engineering (IIJME)
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Design and Finite Element Analysis of Hydro
Test rig for testing piston valve (15-40 NB)
Kunal M. Phalak1, Abhijeet R. Patil1 , Madhura V. Barve1 , P. D. Darade2
1
Department of Mechanical Engineering, Sinhgad Institute of Technology and Science, Narhe, Pune,
1
Department of Mechanical Engineering, Sinhgad Institute of Technology and Science, Narhe, Pune,
1
Department of Mechanical Engineering, Sinhgad Institute of Technology and Science, Narhe, Pune,
2
Assistant Professor, Dept. of Mech. Engg, Sinhgad Institute of Technology and Science, Narhe, Pune.
Abstract
Piston Valve is manufactured by forging. To check leakages in the valves, hydro test rig is used. The valve is subjected to high
pressure of water while it is clamped in the test rig. To withstand such a high pressure we have designed 'hydro test rig'. In the
paper the components of the test rig are designed by theoretical method by calculations and the same design is analysed by
finite Element Method using ANSYS software.
Keywords: Piston valve, Hydro test rig, Finite Element analysis, design
1.INTRODUCTION
A Piston Valve is a zero isolation valve, in which lower and upper sealing rings along with piston replaces seat and
gland. This overcomes the difficulties usually associated with the replacements of conventional seats. The Piston Valve
is a seat less and glandless valve. At the heart of Piston Valve are the piston and sealing rigs. A burnished piston seals
against metal reinforced graphite rigs to achieve bubble tight shutoff. This unique design ensures long life even at high
temperatures up to 425 deg. Celsius.
Piston Valve is made up of forged carbon steel, which provides perfect tightness on different media such as steam,
superheated steam and condensate, heat transfer fluids and compressed air.
Figure 1: Constructional features of piston valve.
The sealing between ports is achieved by piston (outer surface) coming in contact with the inner surface of soft ring
(the lower ring) and the sealing towards atmosphere is achieved by the piston travelling upwards and by forming the
sealing (outer surface of piston and inner surface of upper ring). Hence no gland is required.
A Piston Valve is usually used for the isolation purposes. The Piston valves are used in Diary Industries, Chemical
Industries, Edible Oil Industries, Paint Industries, Petrochemicals Industries, Pharmaceuticals Industries, Fertilizers
Industries, Food Processing Industries, Pulp and Paper Industries, Textiles Industries, Oil and Gas Industries at various
pressure and temperature.
As piston valve is made up of forged carbon steel by forging process, there may be leakage in the body due to the
defects in the manufacturing process. To detect these leakages valves are tested after assembling.
Volume 3, Issue 4, April 2015
Page 36
IPASJ International Journal of Mechanical Engineering (IIJME)
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
Hydro testing as the name implies uses water as the working fluid. It is used to detect leakages present in the pressure
vessels such as pipelines, gas cylinders, boilers, fuel tanks and valves. The purpose of using hydro testing is that water
is testing as well as working fluid which gives the exact results. The pressure for testing is decided by the ANSI
standard used for manufacturing the valve. There are two methods of leak detection namely body leakage test and seat
leakage test. In the body leakage test, valve is completely filled with water, it is pressurised by using air to water
intensifier to 83 bar. The water is kept in the pressurised condition for three minutes. If leakage exists, it is observed by
visual inspection or drop in pressure observed on the pressure gauge. The seat test is carried out in the same fashion but
only the difference is that the valve is at completely closed position whereas in body testing valve is at normally opened
condition. The pressure and the time for both the tests are same.
To perform these tests we have designed hydro test rig for the valve ranging from 15NB to 40NB [1]. The design is
done by theoretical calculations and it is verified by analytically using finite element method by using ANSYS. The
results obtained from both methods are compared and discussed.
2.METHODOLOGY
Two methods are used to obtain the results and to achieve the objective of this study. The methods used are manual
calculation by using ANSI standard and finite element analysis (modelling). Manual calculation is carried out by
calculating the dimensions of the rig. On the other hand, finite element analysis is done by using ANSYS V14.0
software where to performed computer based analysis of the various variable of the component.
2.1 Design by Theoretical method
The skeleton of the test rig is designed like a hydraulic press which consists of top and bottom plate connected by two
tie rods [4]. For testing a specimen valve it is clamped between the two plates. So the main components to be designed
theoretically are top plate, bottom plate and tie rods. For this the following design parameter are used.
Testing pressure = 83 bar (as per ANSI standards for class 300)
Working Pressure = 120 bar
Considering, FOS = 2
Therefore,
Nominal bore of valve = 40 mm
Specifications of Material used:i. Material used for manufacturing the machine: Mild steel
ii. Carbon content in the
mild steel: 0.40 % of carbon
3
iii. Density: 7801Kg/m
2
iv. Ultimate tensile strength of the mild
steel: 650 N/mm
2
v. Young’s modulus: 2.5X105 N/mm
vi. Poisson’s ratio: 0.30
All the components of the rig are designed as per the largest 40NB valve(bore diameter =40mm). While testing the top
and bottom plates are subjected to bending stress and tie rods are subjected to buckling stress..
2.1.1 Design of top and bottom plates
Top plate and bottom plate are subjected to the bending force produce during the clamping hence it is necessary to
consider the bending failure of the system under maximum force exerted by the clamping cylinder [5].
Let,
A = Area of the valve
Area of the valve,
Bending force on the plates,
F1 = Pressure × Area = 24 × 1256.637
F1 = 30159.286 N
Clamping Force,
F2 = 1.5 × F1 = 1.5 × 30159.288 = 45238.932 N
Stroke of the hydraulic cylinder used for clamping in test rig,
S = L1 – L2 + C
Where,
L1 = length of 40 NB valve (class 300) = 317 mm
L2 = length of 15 NB valve (class 300) = 265 mm
C = clearance = 48 mm
S = 317 – 265 + 48 = 100 mm
Volume 3, Issue 4, April 2015
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IPASJ International Journal of Mechanical Engineering (IIJME)
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
Dimensions of the Plates:
Material of the plate = Mild steel
Young’s Modulus of M. S. = E = 210 MPa
Height of the plate [7],
H = flange diameter + (internal clearance × 2) = 156 + (52 × 2) = 260 mm
Length of the plate,
L = flange diameter + (clearance × 2) + (tie rod radius × 2)
L = 156 + (52 × 2) + (10 × 2) = 320 mm
Figure 2: Bottom Plate
Thickness of the plate,
Considering, Allowable deflection in the plate = 0.1 mm
Figure 3: Plate as a simply supported beam
F2 = 45238.932 N
Taking moment about point A, ∑ MA = 0
Maximum deflection in simply supported beam,
I = 1470624.329 mm4
Area moment of inertia of the plate is given by,
2.1.2 Design of Tie Rod
Tie rod is a long column which is subjected to bending and compressive stress due to the plates and hence it undergoes
buckling. Buckling is the phenomenon which a medium or a long column fails by a combination of bending and
compression [5].
Volume 3, Issue 4, April 2015
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IPASJ International Journal of Mechanical Engineering (IIJME)
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
Material of the tie rods = Mild steel
Crushing stress = τc = 320 MPa
Length of tie rod,
L= length of 40 NB valve + (plate thickness × 2) + (flange thickness × 2)= 317 + (40×2) + (30×2) = 457 mm
Diameter of the tie rod,
Considering both the ends of tie rod fixed.
By simplifying the equation becomes,
d4 – 179.999d2 – 80173.126 = 0
d = 19.67 mm
For the safe design we have taken the diameter as 40 mm.
Hence the dimensions obtained from the theoretical calculations are summarized in the below table:
SR. NO.
1.
2.
3.
4.
Table 1: Design Results
Parameter/ Component
Dimensions
Clamping Force
45238.932 N
Stroke
100 mm
Plates (Top and Bottom )
L= 480 mm ,H= 260 mm and
t= 40 mm
Tie rod
L= 457 mm and D= 40 mm
2.2 Finite Element Analysis (FEA) of the Design
The results obtained from the theoretical calculations are analysed by using finite element method by using ANSYS.
For Finite element analysis of the test rig components, the components are modelled in CREO PARAMETRIC V2.0
and assembly of components is done. For analysis purpose ANSYS v14.0 WORKBENCH is used. In this, all the
modelled parts and assembly are uploaded in ANSYS and analysed [2]. The analysis is done according to maximum
deformation theory and maximum stress theory (maximum stress theory).
2.2.1 Analysis of top and bottom plate
After modelling, the boundary conditions loads are applied to the top plate. In this plate both ends are fixed and force
15080 N is applied on one face. The maximum deflection obtained in the plate is 0.023136mm. This deflection is less
than the 0.1mm which is boundary. Similarly the analysis of bottom plate is performed [3]. The force of value 30125N
is applied on one face of bottom plate and both end fixed. We got the maximum deflection as 0.0401mm. As shown in
the figure, the central portion undergoes maximum deflection but deflection is within allowable limit that is 0.1 mm
and stress induced is also less than yield stress in both the plates hence design of the plates is safe.
Volume 3, Issue 4, April 2015
Page 39
IPASJ International Journal of Mechanical Engineering (IIJME)
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
Figure 3: FEA of top plate
Figure 4: FEA of bottom plate
2.2.2Analysis of tie rod
Third major component to be analysed is tie rod. After applying the load on its both ends the linear buckling test is
performed and we got the linear buckling of tie rod the deflection observed in it is 1.028mm which is equal to the
expected value i.e. 1mm and stress induced is also less than the yield stress. Hence the design of tie rod is safe.
Figure 5: FEA of tie rod
2.2.3 Analysis of the assembly
The loads which were applied on top and bottom plate individually before are now applied altogether on the rig
assembly. The results obtained are total deformation and equivalent stress. On comparing both the results with the
given boundary conditions the test rig design is safe. As shown in the picture below, the total deflection in the rig is
0.0470mm which is less than the 0.1mm as per boundary condition considered hence the design is safe.
The von-mises stress theory is used to check whether the design is safe or not by the design or not. According to vonmises theory, the induced stress in element must be less than the yield stress of the material. In this the maximum stress
induced in total test rig is 124.35MPa which is far less than the yield stress of mild steel.
Figure 6: FEA of Rig by Total Deformation Theory
Volume 3, Issue 4, April 2015
Fig.7 FEA of rig by Von-Mises Stress Theory
Page 40
IPASJ International Journal of Mechanical Engineering (IIJME)
A Publisher for Research Motivation........
Volume 3, Issue 4, April 2015
Web Site: http://www.ipasj.org/IIJME/IIJME.htm
Email: [email protected]
ISSN 2321-6441
3.RESULTS AND DISCUSSION
From the above theoretical method of design and finite element analysis, the design results are obtained. The results of
the theoretical calculations are summarized in table 1 while the results obtained by FEA can be stated as follows:
 The Maximum stress induced in the machine frame = 124.35 MPa
 The Maximum Displacement for this load = 0.0470 mm
 The Maximum stress induced in the rig frame (124.35 MPa) is far below the yield stress of Mild steel is i.e. 250
MPa.
 The theoretical Factor of safety can be calculated as
Therefore factor of safety obtained from the Finite Element Analysis method is nearly same as that is considered while
designing by theoretical method.
The deformation caused in each component is checked by maximum deformation theory and it is found that the
deformation produced in each component as well as in the complete assembly is less than 1 mm which is maximum
allowable deformation considered.
4.CONCLUSION
From the results obtained by both and theoretical and analytical method we can conclude that the proposed design of
the test rig is verified by using finite element analysis. All the components designed are safe from both maximum
deformation and stress theory point of view. Hence the design can be applied in the similar industrial applications.
REFERENCES
[1] P.K. Parase, M.V.Kavade & S.H.Limaye: “Design, Development and Testing of Butterfly Valve Leakage Test
Rig”, International Journal on Mechanical Engineering and Robotics (IJMER),pg 74-81,issue 2, volume 1,2013.
[2] Ankit H Parmar, Kinnarraj P Zala, Ankit Patel: “Design and Modification of Foremost Element of Hydraulic
Press”,International Journal of Innovative Science, Engineering & Technology,pg 658-667, Issue 5, July 2014.
[3] Manar Abd Elhakim Eltntawie: “Design Manufacturing and Simulate a Hydraulic Bending Press” International
Journal of Mechanical Engineering and Robotics Research, pg 1-9, on January 2013.
[4] Santoshkumar S. Maniatil, Prof. Yogita Potdar, Prof. A. C. Mattikalli: “Analysis and Structural Optimization of 5
ton H-frame Hydraulic Press”,International Journal of Innovative Science Engineering and Technology, pg 356360, on 5 July, 2014.
[5] Ramamrutham:“Strength of Materials”
[6] V. B. Bhandari:“Design of Machine Elements”
[7] ANSI standards for class 300 SWRF flange.
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