PERFORMANCE PERFORMANCE EVALUATION OF CONTROL EVALUATION OF CONTROL
VALVESVALVES
NIDHIN MANOHAR
TESTING OF VALVES• ROUTINE TESTS
– MATERIAL TEST
– VISUAL INSPECTION
– DIMENSIONAL CHECK
– HYDRAULIC PRESSURE TEST
– GLAND LEAKAGE TEST
– SEAT LEAKAGE TEST
• TYPE TESTS– VALVE FLOW CO-EFFICIENT (CV)
– INHERENT FLOW CHARACTERISTICS
– LIQUID PRESSURE RECOVERY FACTOR (FL)
– PIPING GEOMETRY FACTOR (FP)
MATERIAL TEST
– INSPCTION OF MATERIAL SHALL BE CONDUCTED IN ACCORDANCE WITH THE MATERIAL SPECIFICATIONS
– THE MATERIAL OF WHICH QUALITY HAS BEEN ASCERTAINED MAY BE EXEMPTED FROM THE MATERIAL TEST
Visual InspectionCasting - Shall be free from blow holes, fins, sand
burning, sand holes, scale, cracks etc.Forging - Shall be free from Laps, setting down
flaws etc.Machining - Shall be free from harmful defects.surface Shall be uniformly finishedValve Seat - Valve seat face shall be free from blow holesFlow passage - Well finished and cleaned
EVERY NOOK AND CORNER SHALL BEAPPROPRIATELY CHAMFERED OR ROUNDED
JIS B 200 3 - 1987
Inspection of Dimensions1. Ends : Flange diameter, flange thickness, flange
facings, flange drilling, spot facing, threads and welding end dimensions - as per Std.
2. Flatness : The flatness shall be in such a way that whenof face a straight edge is placed on the face, a feeler
strip of 0.15mm shall not enter anywhere between the straight edge and the contact
face3. Diameter : ‘ID’ of valve as per Standard of end openings4. End to end Dimensions Tolerance on End to End
Nominal size of valve Dimensions 250mm and less +/- 2mm
300mm and more +/- 4mm
Parallelism of Ends
Contact faces - In case of flanged and butt welding ends
Plain or Threaded bores - In case of screwed and socket
welding ends. To be inspected
Nominal Size 50mm and Smaller 20’
Larger than 50mm upto and including 250mm 15’
300mm and larger 10’
)D
AA(Tan 121
Nominal Size
50mm and Smaller 20’
Larger than 50mm upto and including 15’
250mm
30mm and larger 10’
Misalignment between the axes of the ends shall not exceed
0.5mm / 100mm of end to end dimension
Misalignment of Ends
Hydraulic Pressure Test (OR) Shell test
1. Control valve without painting shall be tested
2. Valve ends - Closed
3. Valve opening- Partial
4. Gland packing - Sufficiently tight to maintain the test
pressure
5. Test temperature - Ambient
6. Test pressure - 1.5 times of rated pressure
7. Test time
Nominal Diameter (mm) Test time (sec.)50 (or) less 1565 to 200 60250 or over 180
At intervals of 5 seconds the valve shall be tapped with a soft hammer
There shall be no leakage or wetting of surfaceReference StandardsIS 10189 - Part 1IS 6157 - 1971JIS B 2003 - 1987API 598
Gland Leakage Test
This test shall be made consecutively with shell test or
hydraulic pressure test
Seat Leakage Test
ANSI B 16.104 - Control valves seat leakage
Class I : Modification of Class II, III or IV. No test is required
Class II : 1. Double seat control valves
2. Balanced single port with piston and metalto metal seats
Class III : 1. Class II with higher degree of seat and seal tightness
Class IV : 1. Unbalanced single port single seat
2. Balanced single port with extra tight piston rings or
other sealing means and metal to metal seats
Test Procedure for Class II, III and IV
Test Medium : Water
Test Temperature: Between 10oC and 52oC
Test Pressure : 3 - 4 bar or maximum operating p
whichever is less
Valve Position : Fully closed, outlet open to Atm. Pressure
applied at valve inlet
Leakage rate shall be within the following vales
Class II - 0.5% of rated capacity
Class III - 0.1% of rated capacity
Class IV - 0.01% of rated capacity
Flowrate Data - Accurate to +/- 10% of Reading
Seat Leakage Test for Class V Valves
Class V Valves : Metal seat, unbalanced single port, single seat or
balanced single port with exceptional seat and seal tightness
Test Procedure : Same as than for Class II, III and IV valves except
the following.
Test Pressure : Maximum service p not exceeding the maximum
operating pressure (“ 7 Bar” pressure drop
minimum”
Allowable Leakage Rate - 5 x 10-4 ml / min
Seat Leakage for Class VI ValvesClass VI Valves : Resllient seating control valve either unbalanced
or balanced single port with ‘O’ rings or similar gapless seals
Test Procedure Test medium : Air or Nitrogen gas at 10-52oCTest Pressure : Maximum rated ‘p ‘ or 3.5 bar whichever is less.Allowable Leakage RateNominal Port Dia (mm) ML per minute25 0.1538 0.3051 0.4564 0.6076 0.90102 1.70152 4.00203 6.75
FLOW TEST ON VALVES
• Introduction• The Water Flow Test Facility of FCRI• Test for Cv - Characteristics• Test for FL - Characteristics• Test for Torque Characteristics• Test for Pressure Drop - Flow Characteristics• Conclusion
INTRODUCTION TO THE WATER FLOW TEST FACILITY OF FCRI
• Basic Method Adopted for Flow Measurement• The Water Flow Test Facility• Method of Flow Measurement• Flow Rate Calculation• Overall Uncertainty
WATER FLOW LABORATORY
• TESTING OF VALVES
• CALIBRATION OF FLOWMETERS
• RELATED R&D WORKS
CALIBRATION
• PRIMARY METHOD
• SECONDARY METHOD
PRIMARY METHOD
• USING BASIC PARAMETERS– Length– Mass– Time– Temperature
• (ex.) WEIGHING METHOD
• VOLUMETRIC METHOD
SECONDARY METHOD
• USING A REFERENCE FLOWMETER– ELECTROMAGNETIC FLOWMETERS– TURBINE FLOWMETERS– INSERTION FLOWMETERS
Fig. GRAVIMETRIC WEIGHING SYSTEM
B
A
E
G
M
JL
K
I
H
EF
F
A - Constant head tank - Capacity 50 m^3B - Duplex filter - 600mm N.B.C - Electromagnetic flow meter - 300mm dia.D - Electromagnetic flow meter - 150mm dia.E - 2 High pressure pumps each capable of
delivering 0.125 m^3/sec.at 100 MF - 4 Low pressure pumps each capable of
delivering 1.4 m^3/sec.at 30 MG - Water reservoir - Capacity about 320 m^3H - Control valve diverter system - Capacity 20 TonneI - Control valve diverter system - Capacity 2 TonneJ - Weigh tank - Capacity 20 Tonne
K - Weigh tank - Capacity 2 TonneL - Steelyard for weigh bridgeM - Overflow return line
Schematic of Water flow laboratory
C
D
F
F
L
Test lines (100mm to 600mm)
900mm Test line
N - Electromagnetic flow meter - 600mm dia.
N
CALCULATION OF FLOW RATE
where Q - Volumetric flow rate (m3/hr)
W1 - Initial mass of weigh tank (Kg)
W2 - Final mass of weigh tank (kg) t - Collection time (Sec) - Density of water (kg/m3) (Density of distilled water at line temperature x Relative density of water) B - Buoyancy correction factor (B = 1 + E = 1.00106,
OVERALL UNCERTAINTY = BETTER THAN +/- 0.1%
E aM P
( )1 1
rhmtxxBxWWQ /33600)12(
FISH TAILDIVERTOR
DETERMINATION OF Cv CHARACTERISTICS
• The Test Set up
• Instrumentation
• Method of Test
• Cv Calculation
• Presentation of Result
Cv Test set-up
INSTRUMENTATION
• PARAMETERS TO BE MEASURED
1. Differential Pressure
2. Flowrate
3. Upstream Pressure
4. Temperature of Fluid
5. Valve Travel
1. Differential Pressure Pressure gauge / Pressure Transducer Accuracy - Within +/-2% of Actual value
2. Flow rate Gravimetric method / Reference flowmeter Accuracy - Within +/- 2% of Actual value
3. Upstream Pressure Pressure gauge / Pressure Transducer Accuracy - Within +/- 2% of Actual value
4. Fluid Temperature
RTD / Thermometer
Accuracy - Within +/- 1 deg.C
5. Valve Travel
Dial Gauge / Scale
Accuracy - Within +/- 0.5% of Rated Travel
Cv TEST METHOD• Valve Travel 100%• Differential Pressures a) Just below the onset of cavitation or the maximum available in the test facility whichever is less b) About 50% of (a) c) About 10% of (a)• Mean Cv• % Cv• % Valve Travel
Cv CALCULATION
Where Cv = Valve flow co-efficientQ = Volumetric flow ratedp = Pressure DifferentialGf = Liquid specific gravityN1 = Numerical constant for units of measurements used = 0.865 if ‘dp’ is in ‘Bar’ and ‘Q’ is in m3/hr
2/1
1
)(dpGf
NQ
Cv
)(100)(
%RatedCv
xobtainedCvCv
TravelRatedxTravelValve
TravelValve100
%
Cv Curve
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