Valve Sizing & Test Oct2018 English

Valve Sizing & TestControl Valve

Stanley ParkPresident, P.E.S&T International Co.Mobile : +82(0)10-3840-0721Tel/ Fax : +82(0)2-400-8039E-mail : [email protected]

Globe Valve Butterfly Valve Ball Valve

S&T S&T International Co.

This is a summary of my knowledge, experience in a number of projects, and excerpts from various books and the Internet to help engineers working in the

plant field. October 2018

● Valve Capacity Unit

● Valve Selection Procedure

● Cv Simplified Formula

● Valve Size Selection Example

● Interpretation for Items on the Data Sheet

● Noise Calculation

● Valve Leak Calculation

● Non-Destructive Examination

● Control Valve Various Test

Content

S&T International Co.

1. The valve size is based on fluid dynamics and requires knowledge of fluid properties and limited conditions.

2. Cv(Constant Value)

A unit of valve capacity, expressed as US Gallon(3.785 liters) per minute, when water at 15.6°C flows through the valve at a valve inlet / outlet pressure differential

of 1 psi.

● Valve Capacity Unit


Ø

The larger the Cv, the smaller the seat dia.(Ø) is.

That is, Cv is the valve seat dia. size, and the inlet / outlet diameter of the valve becomes

larger and smaller in proportion thereto.

The Cv value plays a decisive role in defining the valve, and the maximum seat size with the

same Cv value can be applied to the extent that cavitation does not occur.

This is called choked flow and refers to when the pressure drop is so severe that no further

increase in flow rate occurs.

Assuming that the Cv value is 100, the valve should be designed so that the opening of the

valve is usually at least 15(15%) to 85(85%) maximum.

As can be seen from the characteristic curve of the valve:

Operation at less than 15% may result in chattering (vibration due to fluid vortex on the seat

surface and plug head surface) as the gap between the seat and plug becomes narrower,

At 85% or more of operation, the flow rate can be rapidly increased to a small movement of

the plug.

▶ Pipe Coefficient (Fip-Piping Geometry Factor)

▶ Seat Dia.

● Valve Selection Procedure


No

Yes

No

No

Yes

Writing DATA SHEET

CorrectionFactor?

CV CorrectionCalculation

CV Calculation (VALVE Capacity)

Valve Type Selection

Valve Characteristic & Size Decision

Rangeability, Allowable Leak Rate

ProperVelocity? Body Size Change

Noise Calculation

NoiseLimitation?

Noise ControlMeasures

Body, Trim Material Selection

Packing, Gasket Selection

Temp. & Pressure Regulation Suitability

CostEffective?

Actuator and Accessories Selection

Completion of Selection

● Cv Simplified FormulaS&T International Co.

Fluid Pressure Formula(SI Unit) Abbreviation

Liquid Cv = 1.17 x VV: m/hr G: Specific Gravity (Water = 1 ) dP: kg/cm

Gas VapordP < P1 / 2 Cv = V/287 x P1, P2: Valve Inlet/Outlet Pressure(kg/cm.A)

V: m/hr G: Specific Density (Air = 1) t: fluid Temperature (°C)

dP ≥ P1 / 2 Cv = V

SteamdP < P1 / 2 Cv = P1, P2: Valve Inlet/Outlet Pressure(kg/cm.A)

W: kg/hr Tsh: Degree of Superheat (°C)

dP ≥ P1 / 2 Cv =

⁄ ( . + ) ( + )⁄( . + ) ( + )⁄

∗ + . . + ∗ + . ). ∗ ▪ The Cv value in the maximum flow rate and the minimum differential pressure state is the maximum Cv value, and the Cv value in the minimum flow and the

maximum differential pressure state is the minimum Cv value.

▪ It is common to select the nominal diameter by adding a margin of 10 to 20% to the calculated maximum Cv value (when the correction value is less accurate

or when the formula is simplified).

▪ The flow rate under the set pressure condition is insufficient capacity because only the minimum flow rate flows. Therefore, when the differential pressure(ΔP)

is applied, selecting the secondary pressure(P2) as the set pressure + offset 5kgf/cm2 can prevent capacity shortage.

● Valve Size Selection ExampleS&T International Co.

Valve Size Available Trim Cv

inch mm ASME 150, 300, 600 900-1500 25001/2 12 1 1.5 2.53/4 20 1 1.5 2.5 4 61 25 1 1.5 2.5 4 6 9 12 8 6

1 1/2 40 1 1.5 2.5 4 6 9 12 16 20 25 20 162 50 1 1.5 2.5 4 6 9 12 16 20 25 30 35 46 36 253 80 15 25 30 46 75 99 76 504 100 25 46 75 110 135 195 135 110

Table 2: Contoured and Multi-Step Trims(Severn Glocon Catalogue)

Note: Multi-step trim options are indicated in green.

If you want to supply water with P1 pressure of 6kgf / cm2, P2 pressure of 3kgf / cm2, and flow rate of 20m3 / hr, what is the valve size?

1. Cv Calculation

2. Valve Size SelectionThe designer can obtain a catalog of several makers beforehand, and when selecting a valve, the valve size can be easily selected by calculating the Cv value.

In case of special case, designers directly designate size etc. in consideration of all characteristics, but In the general case, the performance of the valve is

reviewed and evaluated based on the recommendation of the manufacturer.

15)35.0(6

12017.11117.1 =+-

´´=´´=PGQCv△

v Q = Flow Rate, G1 = Specific Gravity

ΔP = P1 - (Offset 0.5 + P2)


▪ Tag Number: To indicate the role of the valve in the system, distinguish the Tag # Initial by alphabet.FV-xxx controls the flow rate, TV-xxx controls the temperature, PV-xxx controls the pressure, HV-xxx controls the Choke valve in the Local Control Panel by hand.

▪ Valve Name: Give the system a name after its use or application location.Example - Gas to Flare: The purpose of sending gas to the Flare Stack. Pump

▪ CASE I, -II, -III, -IV(flow rate, pressure, temperature, etc.): Valve Max., Normal, Min. means that the plant is operated by increasing the future capacity and by

spring, summer, autumn, winter or emergency, or the rise in the flow and pressure from the subsea oil field and the gas field

indicates different conditions depending on the initial, middle, and late periods

▪ Vapor Pressure: Refer to my article "Valve Cavitation" as an element that causes cavitation or flashing in the valve.▪ Viscosity: If the oil sludge is a fluid, consider Hole Dia. It should be designed large.▪ Required Cv: Valve is designed with a flow margin of about 20%, which is the value obtained by simple Cv calculation.

▪ 밸브 Travel: Normally, Globe Type is estimated at 60% - 70%, but sometimes it is required to 50% in order to increase plant

production. Even though the Anti-surge valve is a fast stroke, since the effective flow rate at the compressor suction is only

about 60% due to the time difference, the effective fluid rate for Joule Thomson valve to lower the temperature by expanding

the gas through the valve is about 80%, hence the flow rate shall be 1.25 times, and 1.5 times for Expander Bypass.The Butterfly type is between 45% and 50%, but be careful not to operate less than 15%. As shown in the valve characteristic

curve, when the valve inlet pressure is high, the chattering is likely to occur at below 15% (the valve outlet pressure is 0 barg

when the valve is completely closed).▪ Acceptable Noise Levels: Do not exceed the values recommended by Occupational Safety & Health Administration(OSHA).

That is, 24-hour operation(85dBA and less), intermittent operation(90dBA), Infrequent operation(105dBA). Noise generation

elements include Mechanical vibration, Hydro-dynamic noise(Cavitation, Flashing, Turbulence), and Aero-dynamic noise

(Turbulence at Vena Contract).

● Interpretation for Items on the Data Sheet


▪ Body/Bonnet Material: It is designed according to customer's piping spec. and fluid type and temperature.

ANSI Class 150# ASTM A216 WCB cast iron valves can be used up to 20kg/cm2 at temperatures below 38°C and up to 5.5kg/cm2 at 427°C. Therefore, ANSI Class 150#

WC is not necessarily available within 150#(10kgkg/cm2), but the operating pressure is different depending on temperature. The special material is expensive and uses

overlay or cladding to coat only inside the body for cost effective.

Overlay Welding rod of special material is attached to the wall by arc welding, and then the surface is polished with a grinder.

Cladding Unlike joining two materials, the welding metal is placed on the surface of the base material and welded.

Overlay Welding Clad Welding


Stellite® For erosion resistance and corrosion resistance, the welding electrode is Co, Cr, W (cobalt/ chrome/ tungsten) alloy coated with Plasma Transferred Arc Welding

and hardness is not lowered even at high temperature. For large diameter seat ring and seat Stellite® is required, the implementation of Leakage Class V and VI

requires a high level skilled manufacturing process.

Plating A coating method in which a metal product is connected to a negative electrode (-), a metal to be coated on the surface is connected to a positive electrode (+),

two metals are immersed in the electrolyte solution.

Enthalpy of the system and state of matterPrinciples of Plasma WeldingPlating


▪ Pipe Line: Valve ANSI Class Rating and materials are the base data for the specification, which is specified by the customer and the supplier usually follows this standard.

▪ Valve Type: In recent years, the control valve is almost always designated as the Globe Type. However, it is also possible to specify an economical butterfly type for large

flow and low pressure, and a ball type (MOV for almost all) when Pig Launcher for removing sludge in pipe is applied.

▪ Valve Size: It refers to the flange size of the valve. All manufacturers use the Valve Sizing Program to select the valve, its value as Cv, and the valve size from its own

catalogue. Some manufacturers quote a smaller valve size for price competitiveness, which is directly related to the valve travel.

Globe, Butterfly, Ball Type Design conforms to standards such as ANSI, ASME, ISA, EN, etc. TEST conforms to API, ASME, ISA, ISO, MSS SP Standard

Wellhead Choke Valves are subject to slight dimensional differences by manufacturer and must receive separate dimensional drawings.

▪ ANSI Class: Refer to the attached ANSI Class Rating Table for material, temperature and maximum pressure.

▪ Maximum Pressure: It is used with the same concept as Design Pressure. If this value is not displayed, Critical Pressure is also applied.

▪ Pipeline Insulation: Insulation plays a role as a sound absorbing material at the same time, and the effect of insulation (sound absorption) varies depending on its kind,

thickness and density. This should be applied by seeking technical consultation with insulation makers.

▪ Bonnet Type: Union Bonnet(for low temperature/low pressure), Screwed Bonnet(for small diameter/low pressure), Bolted Flanged Yoke Bonnet(OS & Y, no corrosion

concerns and for manual valves), Bolted Flanged Bonnet(For high temperature/high pressure), Plain Bonnet(for -20°C to 230°C), Fin Bonnet (Heat dissipation for gland

packing protection), Extended Bonnet(Liquefied hydrogen, Icing prevention around packing and stem for LNG), Bellow Seal Bonnet(for toxic, explosive, high temperature

fluid) and Special Seal Bonnet

▪ Flange Surface Roughness : Roughness Tester ►

- Ra(Center line average roughness) The mean deviation of peaks and valleys deviating from the mean line

over the entire length of the roughness curve

- Rmax(Maximum height) Vertical distance from the highest peak to the deepest valley with a section curve

- Rz(10 point average roughness) In section curves, mean depth difference for the average height of the six highest peaks and the five deepest valleys

▪ Packing Type/Material: PTFE (up to 30kg/cm2 for pressure, -200°C to 230°C), Grafoil (low coefficient of friction and up to 3,500°C), Neoprene, Buna-N(apply V-shaped

ring to low temperature air or water, etc.). In recent years, almost all specifications require VOC packaging (see my Fugitive Emission Article).Fugitive Emission Bellow seal is required to meet the tightness class A, but a valve size greater than 2 "does not apply due to the yield strength of the material.


▪ Trim Size: Rated Cv value is obtained by determining and is usually the same as the seat diameter.

▪ Trim Type: Marked as Contoured, Drilled Hole Cage(1CC, 2CC, 3CC, 4CC), Multi-path/Multi-stage or Standard, Anti-Cavitation, Low Noise

▪ Trim Characteristic: Linear (Level Control, Anti-surge valve if Delta P is constant), Equal% (constant flow rate changes to percent constant in valve opening, applied as

pressure control), Modified Parabolic (often used as an alternative to Equal%), Quick Opening (Not applicable)

▪ Plug Type: Unbalanced There is no hole for pressure equilibrium in the plug. Low Delta P is applied or small size valve.

Balanced Hole is installed for balancing in the plug and a pilot plug is installed so that pressure balance is achieved. Since the soft seat is not suitable at high

pressure and high temperature, set the single seat to reduce the leaks. For large capacity, install the single seat valve for the balance due to the force limit of

the actuator.

▪ Plug Material: In general, hard facings are applied to the area of contact with the fluid for erosion resistance and corrosion resistance.

▪ Seat Material: Single Seat Actuator force is required to be larger than double seat for the same capacity.

Double Seat Leakage of fluid is present, but operation is stable and operation force is low.

Soft Seat PTFE, Viton, and Rubber. However, it is difficult to apply to high temperature and high pressure.

Metal Seat Tight shut-off is difficult, but suitable for high temperature and high pressure.

▪ Cage/Guide Material: It is applied as hardened material instead of hard facing because many drilled holes can not be machined.

▪ Actuator Type: Pneumatic, Hydraulic (Electro-Hydraulic). Refer to the article on my Actuator Type and Features for details.

▪ Failure Mode: If the air supply is interrupted, it indicates whether the valve is open (Open) or closed (Close).

Fail open must flow fluid to the system(Fire water) and Fail Close should not flow fluid (toxic gas, explosive gas, etc.).

▪ Supply Type: means Pneumatic Air or Oil

▪ Available Supply Pressure(Min./Max.): Refer to the figure for the control valve signal processing.(Normally 100psi Max. = 17.0kgf/cm2)

▪ Handwheel Type: Top Mounting (mainly for small size: 6 "or less). Side Mounting (mainly for large size)

▪ Air Volume Tank: It must be designed to withstand pressures of at least 9.3kg/cm2g(135psig) and must be manufactured in accordance with ASME VIII-Section 1

(UM Stamp) requirements. The capacity of the Control Valve should be at least two complete strokes at a minimum usable device pressure of 4.15kg/cm2(60psig)


Control Valve Signal Processing

I/P Transducer: Converter from electrical signal to air signal

Positioner : Receives air pressure signal of 0.2 - 1.0kg/cm2 controlled from I/P Transducer and sends air signal proportional to it to valve actuator, and

control the opening of the valve by receiving the position of the valve stem.


▪ Shut-off Pressure: There are 2 conditions on Pressure Control Valve(PCV) and Shut Down Valve(SDV).

a. Shut off Pressure

b. Maximum Differential Pressure for Actuator sizing. System sequence is,

Vessel A (Operating Pressure= 4.5barg) -----> PCV( Pressure Drop= 4bar). -----> SDV. -----> Vessel B (Operating Pressure= 0.5barg).

Vessel A (Design Pressure= 12.0barg). Vessel B (Design Pressure= 4.0barg)

a. Shut-off Pressure for Valve Tightness: Worst Case Design Pressure - Atmospheric Pressure = 12bar

b. Max. Differential Pressure at Actuator Design: Differential pressure at inlet / outlet of control valve requires big torque and actuator should be bigger(additional cost).

▪ Positioner Type: There are E/P Positioner와 Smart Positioner(Refer to my article “Control Valve Accessory”).

▪ Positioner Input Signal: Normally 3- 15psi(0.2 – 1.0kg/cm2)▪ Positioner Output Increase/Decrease at Signal Increase: It is related to the operation of the plant as required by the customer.

▪ Filter Regulator: Normally, 1.2 - 5.0kg/cm2 is used for pneumatic control system, and the pressure is reduced and impurities such as moisture and dust are removed.

▪ Limit/ Torque Switch: A device that sends a signal to check whether a valve is opened or closed, or sends a signal that can operate a warning or other valve

▪ Seat Leakage: Refer to my Article “Valve Seat Leakage Class”

▪ Partial Stroke Test(PST): This technique is used in control systems to test possible fail-mode percentages of shut-down valves without having to physically close valves.It is generally used in 90 degree rotary type valves such as ball valve and butterfly valve. Normally, the emergency shut-off valve requires a PST to verify that the

emergency shut-off valve is in fact functioning, since the frequency of operation during operation of the plant is very small and usually not very active at all times. If you do

not check it in the middle, it can be connected to a big accident if it does not work when it is actually needed due to mechanical sticking (Block)PST is used to assist in determining that the safety function will operate on demand. PST is most often used on high integrity emergency shutdown valves (ESDVs) in applications where closing the valve will have a high cost burden yet proving the integrity of the valve is essential to maintaining a safe facility. In addition to ESDVs PST is also used on high integrity pressure protection systems or HIPPS. IEC61508 adapts a safety life cycle approach to the management of plant safety. During the design phase of this life cycle of a safety system the required safety performance level is determined using techniques such as Markov Analysis, FMEA, Fault Tree Analysis and HAZOP. These techniques allow the user to determine the potential frequency and consequence of hazardous activities and to quantify the level of risk. A common method for this quantification is the safety integrity level. This is quantified from one to four with level four being the most hazardous.


▪ Positioner Cam Characteristic: There really isn’t a simple way of adding or subtracting points on the installed flow characteristic to explain how the modification works.

Hopefully the following will clarify how the modification graph is constructed: I will do this by randomly choosing two controller output values on the horizontal axis, a

controller output (and therefore a uncorrected valve position) of 45% and of 60%. When the controller output (and the valve position) is 45% the flow at Point 1 will be

10% of the fully open flow. If it is desired for the system to have a linear relationship between controller output and flow (the heavy line on the graph “Desired Flow vs.

Controller Output” when the controller output is 45% the valve must be positioned, not at 45% but at a point where the flow will be 45% of the fully open flow. Following

the dashed installed flow curve to Point 2 on the installed flow curve where the flow will be the desired 45% the valve will need to be 81% open. So at this point the

modification must convert the controller’s 45% output to 81%, Point 3 on the modification graph. Looking at a second point, where the controller output is 60%, Point 4 on

the installed flow graph would put the flow at 20%, not the desired 60%. Following 60% flow to Point 5 on the installed flow graph tells us that to get 60% flow, the valve

needs to be at 88% open. So at this point the modification must convert the controller’s 60% output to 88%, Point 6 on the modification graph. If we were to repeat this

process, say, for a total of ten evenly spaced controller outputs we would get the modification (lower graph) in the figure.

Positioner Cam Characteristic Curve

A valve with a non-linear installed flow characteristic can have its characteristic ►

Modified to give a linear relationship between controller output and flow by

programming a modification curve into the DCS output or a digital positioner.

Rating of SIL(Safety Integrity Level)

SIL PFD average (average probability of failure on demand)

4 1/100,000 to ＜1/10,0003 ≥1/10,000 to ＜1/1,0002 ≥1/1,000 to ＜1/1001 ≥1/100 to ＜10


Aero-Dynamic Noise Prediction

1. Calculation by Graph

SPL = SPL ΔP + ΔSPL cg + SPL ΔP/P1 + ΔSPL k

SPL: As overall noise dB, Sound Pressure at 42 "(107 cm) from

the valve outlet and 29" (74 cm) from the pipe surface

SPL ΔP: Differential Sound Pressure Correction Factor (Fig. 1)

ΔSPL cg: Sound Pressure Correction Factor for Gas (Fig. 2)

H: Sound Pressure Correction Factor for Pressure and Valve Type

ΔSPL k: Sound Pressure Correction Factor for Pipe Thickness,

Silencer, and Insulation (Table 1)

Cd: Relative Flow Capacity(= 645*Cv/d2)

(Fig. 1 ) Differential Pressure (Fig. 2) Globe (Cage) Gas PressureCorrection Coefficient Correction Coefficient

Example In case of ANSI 300# x 4”, Globe Valve, Sch 80, Line

Size 8” P1: 615psi P2: 252psi ΔP: 348psia ΔP/P1: 0.57,

Noise Calculation is;

SPL ΔP = +51dBA(Fig. 2) ΔSPL k = -30.9dBA(Table1)

ΔSPL cg = +72dBA(Fig. 1)

SPL ΔP/P1 = +15.5dBA(Fig. 3) SPL = 51 + 72 – 30.9

= 107.6dBA

● Noise Calculation

dBAdBA


(Table 1) Pipe Thickness Sound Pressure Correction Factor (dBA)

Pipe Size (in)

Steel Schedule

10 20 30 40 60 80 100 120 140 160 STD XS XXS1 - - - -19.0 - -21.6 - - - -24.5 -19.0 -21.6 -27.6

1 1/2 - - - -19.8 - -22.6 - - - -25.6 -19.8 -22.6 -28.62 - - - -20.4 - -23.4 - - - -27.3 -204 -23.4 -29.43 - - - -23.4 - -26.2 - - - -29.5 -23.4 -26.2 -32.34 - - - -24.2 - -27.2 - -29.5 - -31.2 -24.2 -27.2 -33.26 - - - -25.9 - -29.5 - -31.8 - -33.9 -25.8 -29.5 -35.58 - -24.9 -25.8 -27.1 -29.1 -30.9 -32.4 -34.1 -35.1 -36.1 -27.1 -30.9 -35.8

10 - -24.9 -26.7 -28.2 -31.0 -32.4 -34.1 -35.5 -37.0 -38.0 -28.2 -31.0 -12 - -25.1 -27.5 -29.3 -32.1 -33.8 -35.6 -37.1 -38.1 -39.5 -28.6 -31.1 -14 -25.4 -27.1 -28.7 -30.0 -32.6 -34.7 -36.6 -38.0 -39.1 -40.1 -28.7 -31.2 -16 -25.3 -27.2 -28.8 -31.3 -33.6 -35.8 -37.6 -39.0 -40.4 -41.3 -28.8 -31.3 -18 -25.3 -272 -30.1 -32.3 -34.8 -36.7 -38.6 -40.1 -41.2 -42.3 -28.8 -31.3 -20 -25.4 -28.9 -31.4 -32.9 -35.6 -37.7 -39.1 -40.9 -42.3 -43.3 -28.9 -31.4 -24 -25.6 -29.1 -32.6 -34.4 -37.4 -39.4 -41.3 -42.8 -43.9 -45.0 -29.1 -32.5 -30 -27.7 31.8 -33.7 - - - - - - -29.3 -32.7 -36 -28.0 -32.2 -34.1 -35.6 - -21.6 - - - - -29.6 -32.1 -42 - - - - - - - - - - -29.8 -32.3 -46 - - - - - - - - - - -29.9 -32.4 -48 - - - - - - - - - - -30.0 -26.2 -32.552 - - - - - - - - - - -30.2 -27.2 -33.256 - - - - - - - - - - -30.3 -32.8 -60 - - - - - - - - - - -30.4 -32.9 -

(Fig.3) Globe Valve Differential Pressure

Ratio (ΔP / P1) Correction Coefficient


Aero-Dynamic Noise Prediction

1. Mathematical Calculation by GraphIt is a formula for calculating the aerodynamic noise that occurs when air, gas, or steam is used under critical differential pressure conditions.SPL = 10log10(X•η•20•2•Cv•FL•P1•P2•1012) – TL + Sg + 3SPL : Value at 91 cm from the valve(based on 1dBA = 2 x 10-4μ bar)Cv : Actual required valveFL : Inlet side pressure recovery coefficient, dimensionlessP1 : Valve Inlet Pressure(kg/cm2)P2 : Valve Outlet Pressure(kg/cm2)m : Pipe Weight(kg/m2) (Table 1) n : Frequency generation coefficient (Table 2)TL : Transmission loss

dBA = 17log10(3072m•n•/ • (Omitted for valves that emit directly into the atmosphere)

P2 Crit = P1 – F2L/(P1 – Pv)〔kg/cm2A〕 : If the difference of Kc(Cavitation Generation coefficient) and F2L is more than 10%, use Kc instead.

Pv = Vapor pressure of fluid(kg/cm2A)X = Converted Fractions of Mechanical output(= P1 – P2/ 0.47 x ＜1 less)η = Acoustic efficiency coefficient(Fig. 2) Sg = Intrinsic correction factor of gas(Table 3)

ExampleWhen Globe 2-1/2” x 1-1/4”, FL -0.8 of Valve is installed at Pipe Size 4B, Sch 40 under Steam P1= 3kg/cm2g (4.033kg/cm2A), P= 0.43kg/cm2g(1.463kg/cm2A), the Noise Calculation is;SPL = 10log10(1,356 x 0.00037 x 20.2 x 10,596 x 0.8 x 4.033 x x1.463 x 1012) – 49.7 + (-2) + 3 = 68.35dBA

SIZEm

Sch. 40 (kg/cm2)

m Sch. 80 (kg/cm2)

m Sch. 160 (kg/cm2)

1/2 22.8 30.6 43.21 26.4 35.6 49.8

1 1/2 29.0 40.0 55.72 30.8 43.5 68.4

2 1/2 40.8 55.0 74.63 43.0 59.6 80.94 47.4 66.9 105.55 51.8 74.6 124.86 55.7 85.9 142.68 64.0 99.6 180.610 72.7 117.7 224.612 80.6 136.7 260.714 87.1 149.1 280.216 99.7 168.0 317.918 112.2 186.8 354.820 118.5 205.7 392.524 136.6 242.5 467.0

(Table 1) Pipe Weight Unit (M)


Saturated Steam -2Superheated Steam -3Natural Gas -1Hydrogen -10Oxygen +0.5Ammonia -2Air 0Acetylene -1Carbon Dioxide -1Carbon Monoxide 0Helium -6.5Methane -1 Nitrogen 0Propane +1 Ethylene -1Ethane -1

(Table 3) Gas Intrinsic Correction Factor

(Fig. 1) Sound Pressure Correction Factor by Differential Pressure. (SPLΔP)

Valve Type n Factor

Control Ball Valve 1.0V-Ball 1.4Single Port(Globe Valve) 1.4Angle Valve 1.4Butterfly Valve 1.4Double Port(Globe Valve) 2.24 Port Cage Valve 2.2

(Table 2) Frequency Generation Coefficient (N))

(Fig. 2) Acoustic Efficiency Coefficient


Hydro-Dynamic Noise Calculation

1. Calculation by Graph

SPL = SPLΔP + ΔSPL Cv + SPLΔP/(PL – Pv) + ΔSPL k

ΔSPL Cv : Sound Pressure Correction for Cv

SPLΔP/(PL – Pv) : Sound Pressure Correction according to Valve Shape

Example

Globe Standard Trim Cv=70 P1=250 psig, ΔP=175psia Vapor P(Pv)

SPL = SPLΔP + ΔSPL Cv + SPLΔP/(PL – Pv) + ΔSPL k

= 59 + 37 – 8 +10 = 88dBA

2. Mathematical Experience Formula

Noise is the highest in the cavitation state that occurs when the fluid is a

choked flow of liquid = F2L / (PL-Pv).The following is an empirical formula to predict noise when the pipe is Sch 40.

SPL = 10log10(Cv • FL) + 8log1014.223(P2crit – P2) +20log1014.223(P2-Pv) + 33

(Fig. 2) Valve Capacity (Cv) Sound Pressure Correction Factor

(Fig. 1) Correction Factor of Sound Pressure according to Valve Shape, SPLΔP/(P1-Pv)

● Valve Leak Calculation


Cv = 1.17 * V *

Example

In case of Valve Size = 6 inch, Cv = 175, Leakage Class IV, Test Pressure = 3kg/cm2, Leak amount is;

VLeak = 1000 * 175 * 0.0001 * 60*1.17

= 0.43L/min. = 26L/hr

V = Cv * Δ1.17 *

Leak amount = Cv value * Allowable Rate


Method Principle Detection Object / Application Remarks

1. Radiographic Test

When the transmissive radiation is projected on the test body, the defect is checked by the difference in the intensity of the transmitted radiation. That is, due to the difference in the transmission dose of the sound part and the bonding part, the defect is checked using the difference in density on the film

Detect internal / external defects of most materials such as welds and castings

- Permanent recording means- Applicable to all kinds of materials- Possible to detect surface defects and internal

defects- Radiation Safety Management Requirement

2. Ultrasonic Test

A technique of detecting discontinuity in an object by using a phenomenon in which ultrasonic acoustic impedance is reflected and refracted at another interface

Internal defect detection and thickness measurement for welds, castings, rolled products, and forgings

- Ability to estimate location and size of defects- Surface and internal defect inspection possible- Automatable

3. Magnetic Particle Test

When leakage magnetic flux is formed in the discontinuity part when magnetizing the object to be inspected, the magnetic flux is applied to this part and the magnetic flux is concentrated

Derivation of surface and under-surface defect of ferromagnetic material

- Applicable only to ferromagnetic materials- Devices and methods are simple- Visually identifiable defects- Not applicable to nonmagnetic materials- Fast and inexpensive

4. Penetration Test

As a technique to detect defects open to the surface, it is visually identified by applying developer after penetration liquid penetrates by capillary phenomenon

Surface open defect detectionfor non-porous materials such as welds and forgings

- Applied to almost all materials- Easy to apply in the field.- It is not limited to the size of the product.- equipment and methods are simple

5. Positive Material Identification (PMI)

XRF: X-Ray Fluorescence Transitions Used when you can not test in the usual way, if you suspect a mixture of materials, if the composition of the material is very important, or if you can not destroy the sample

Fluorescence X-ray is the most commonly used PMI method When the X-ray line is irradiated, the detector reads the second X-ray coming from the element, and the XRF instrument is used.

Spectroscopic AnalysisIt is based on optical emission, and its equipment consists of a sensor that analyzes the components by vaporizing the sample and a probe that emits flash

● Non-Destructive Examination


1. Radiography Test 2. Ultrasonic Test

3. Magnetic Test 4. Penetration Test

1. Induce a magnetic field in the specimen.2. Apply magnetic particles to the specimen’s surface.3. View the surface to look for particle grouping due to defects.4. De-magnetize and remove the specimen.


Operating Principle Comparison: Spectroscopic AnalysisFluorescence Spectrophotometer vs. UV-Vis Spectrophotometer

Portable Mounting Type

5. Positive Material Identification(PMI)

XRF(X-ray Fluorescence) Spectroscopic Analysis Meter


Surface Hardness Test

SHAPE of INDENTATION

Test Indenter Side View Top View Load, P Hardness Number

Brinell 10mm Steel or Tungsten Carbide Ball

500kg 1,500kg 3,000kg

HB =

Rockwell

A

Diamond Cone

60kg HRA

100 - 500tC 150kg HRC

D 100kg HRD

B

1/16inch Diameter Steel Ball

100kg HRB

130 - 500tF 60kg HRF

G 150kg HRG

E 1/8ich Diameter Steel Ball 100kg HRE

Vickers Diamond Pyramid 1kg - 20kg HV = 1.854P/L2

Knoop Diamond Pyramid 25g - 5kg HK = 14.2P/L2

−


Typical Hydrostatic Pressure Test

● Control Valve Various Test

TEST PRESSURE by CLASS - ANSI B16.34 Unit: psig

Material Item 150lb 300lb 600lb 900lb 1500lb 2500lb

WCBMax. Operating Pressure 285 740 1480 2220 3705 6170Shell 450 1125 2225 3350 5575 9275Seat 315 815 1630 2445 4080 6790

WCB, WC9 C5, C12, LC2, LC3

Max. Operating Pressure 290 750 1500 2250 3750 6250Shell 450 1125 2225 3375 5625 9375Seat 320 825 1650 2475 4125 6875

CF8, CF8M, CF3, CF3M

Max. Operating Pressure 275 720 1440 2160 3600 6000Shell 425 1100 2125 3250 5400 9000Seat 305 795 1585 2380 3960 6600

CN7MMax. Operating Pressure 230 600 1200 1800 3000 5000Shell 350 900 1800 2700 4500 7500Seat 255 660 1320 1980 3300 5500

LCB, LC1Max. Operating Pressure 265 695 1390 2085 3470 5785Shell 400 1050 2100 3150 5225 8700Seat 296 765 1530 2295 3820 6365

TEST TIME(Min.) - API 598 Unit : second

Valve Size Shell Back Seat Seat Remark2" and below 15 15 15

2-1/2" - 6" 60 60 608" - 12' 120 60 120

14" and above 300 60 120


Typical Cv Test Setup

Cv(Constant Value): In the mid-1940s, Masoneilan's Rockwel announced that the unit of valve capacity, expressed the flow rate by US Gallon(3.7853 liter) per minute,

when 15.6°C water flows under 1 psi of pressure at the valve inlet and outlet.

● The below parameters can be obtained by the test(ANSI/ISA-75.02).

Cv : Valve Flow Coefficient

FL : Liquid Pressure Recovery Factor

Fp : Piping Geometry Factor

FLP : Product of the Liquid Pressure Recovery Factor

FR : Reynolds Number Factor and the Piping Geometry Factor

FF : Liquid Critical Pressure Ratio


Typical Functional Test Setup - Control Valve Typical Cryogenic Test

Test Procedure Test Procedure

1. Dip the valve into liquid nitrogen and check with a thermometer whether the internal temperature drops to -196°C.

2. Under the cryogenic temperature, carry out high pressure seat leak test and shell leak test

3. Perform valve functional test(open-close) at the same time

1. The valve, I/P positioner, current source generator, and instrument air supply are set up. Instrument air supply P is checked. It is set according to the I/P positioner requirements.

2. 4mA current signal is applied to the I/P positioner. The valve stem shall be in 0% travel. 20mA current signal is applied to the I/P positioner; the valve stem shall be in 100% travel. If the valve stem travel indication did not show correctly 0% or 100% travel, then travel is calibrated using the HART communicator.

3. The five point stem travel is checked for Hysteresis and Linearity check on 0%, 25%, 50%, 75, 100% and then 100%, 75%, 50%, 25% and 0% stem travel.

4. The three point stem travel is checked for Dead-band check on 5%, 50% and 95% stem travel.

Documents

Valve Sizing & Test Oct2018 English