pipe sizing
TRANSCRIPT
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PRESENTATION TO TRAINEES PRESENTATION TO TRAINEES ONON
PIPE SIZINGPIPE SIZING
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PIPE SIZINGPIPE SIZINGPIPE SIZINGPIPE SIZING
PIPING CENTRE, CHENNAI
Length – “ l ”
Diameter – “d ”
Cross Sectional Area of Cylinder = * d2/4
Volume of Cylinder = Area * Length = (* d2/4) * ( l )
Suppose the Cylinder is filled with Water, Mass of Water in the Cylinder
= Volume * density of water = (* d2/4) * (l) *
Density = Mass / Volume (unit is kg/m3)
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PIPE SIZINGPIPE SIZINGPIPE SIZINGPIPE SIZING
Mass of water in the Cylinder (m) = (* d2/4) * (l) *
Suppose the water in the cylinder is flowing at a rate of ‘m’ kg in time ‘t’
Flow rate (Q) = m/t = (* d2/4) * (l/t) *
Velocity of flow in the cylinder – (Displacement / time) = (l/t) = ‘v’ m/s
Q = (* d2/4) * (v) *
Q – flow rate (kg/s) , d – Internal diameter of Pipe in “m’
V – velocity of fluid in m/s , – density in kg / m3
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PIPE SIZINGPIPE SIZINGPIPE SIZINGPIPE SIZING
Q = (* d2/4) * (v) *
Q – flow rate (kg/s) , d – Internal diameter of Pipe in “m’
V – velocity of fluid in m/s , – density in kg / m3
Normally following units are used
Q – flow rate (tonnes/hr) , d – Internal diameter of Pipe in “mm’
V – velocity of fluid in m/s ,
Instead of density – density in kg / m3,
Specific Volume “”= 1/ , unit in m3/kg
Q = (* d2/4) * (v) * becomes
Q * (1000/3600) = * (d/1000)2/4 *(v) * (1/ )
Therfore d2 = 4*Q*(1000/3600) *(1/v)*(1000)2/
ID of Pipe ‘d’ in mm = 595*SQRT(Q* / v)
d = 595*SQRT(flow*spvol/velocity)
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INPUTS REQUIRED FOR PIPE SIZINGINPUTS REQUIRED FOR PIPE SIZINGINPUTS REQUIRED FOR PIPE SIZINGINPUTS REQUIRED FOR PIPE SIZING
FLOW (TONNES / HR)FLOW (TONNES / HR)
VELOCITY OF FLUID (M/S)VELOCITY OF FLUID (M/S)
SPECIFIC VOLUME OF FLUID (MSPECIFIC VOLUME OF FLUID (M33/KG)/KG)
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FLOWFLOWFLOWFLOW
The flow to various equipments are The flow to various equipments are decided by the respective Equipment decided by the respective Equipment Manufacturers. The Turbine Manufacturer Manufacturers. The Turbine Manufacturer decides the quantity of steam or water decides the quantity of steam or water from / to various TG equipments like from / to various TG equipments like Turbine, Condenser, Heaters etc. The Turbine, Condenser, Heaters etc. The Boiler manufacturer decides the quantity Boiler manufacturer decides the quantity of steam or water to from various Boiler of steam or water to from various Boiler side equipments like Boiler, Air heaters, side equipments like Boiler, Air heaters, Fans etc. Fans etc.
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SPECIFIC VOLUMESPECIFIC VOLUMESPECIFIC VOLUMESPECIFIC VOLUME
SPECIFIC VOLUME OF A FLUID SPECIFIC VOLUME OF A FLUID DEPENDS ON THE WORKING PRESSURE DEPENDS ON THE WORKING PRESSURE AND WORKING TEMPERATURE OF THE AND WORKING TEMPERATURE OF THE FLUID. THE SPECIFIC VOLUME IS FLUID. THE SPECIFIC VOLUME IS OBTAINED FROM THE STEAM TABLES.OBTAINED FROM THE STEAM TABLES.
WORKING PRESSURE IS EXPRESSED IN WORKING PRESSURE IS EXPRESSED IN THE UNIT kg/cmTHE UNIT kg/cm22(abs) ie Reading of (abs) ie Reading of Pressure Gauge + Atmospheric Pressure Pressure Gauge + Atmospheric Pressure which is 1 kg/cmwhich is 1 kg/cm22
WORKING TEMPERATURE IS WORKING TEMPERATURE IS EXPRESSED IN THE UNIT DEGREE EXPRESSED IN THE UNIT DEGREE CELSIUS - CELSIUS - ooCC
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SPECIFIC VOLUMESPECIFIC VOLUMESPECIFIC VOLUMESPECIFIC VOLUME
For Steam at a Pressure of 16 kg/cmFor Steam at a Pressure of 16 kg/cm22(abs) (abs) and 210and 210ooC the specific volume is 0.12991 C the specific volume is 0.12991 mm33/kg./kg.
For Steam at a Pressure of 179 For Steam at a Pressure of 179 kg/cmkg/cm22(abs) and 540(abs) and 540ooC the specific C the specific volume is 0.01884 mvolume is 0.01884 m33/kg/kg
For Water at a Pressure of 200 For Water at a Pressure of 200 kg/cmkg/cm22(abs) and 160(abs) and 160ooC the specific C the specific volume is 0.00109 mvolume is 0.00109 m33/kg/kg
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CHARACTERISTICS OF SPECIFIC VOLUMECHARACTERISTICS OF SPECIFIC VOLUMECHARACTERISTICS OF SPECIFIC VOLUMECHARACTERISTICS OF SPECIFIC VOLUME
For Steam and water at the same pressure , specific volume For Steam and water at the same pressure , specific volume increases with temperatureincreases with temperature
16 kg/cm16 kg/cm22, 210, 210ooC – 0.12911 mC – 0.12911 m33/kg/kg
16 kg/cm16 kg/cm22, 310, 310ooC – 0.16521 mC – 0.16521 m33/kg/kg
For Steam, at the same temperature, specific volume decreases For Steam, at the same temperature, specific volume decreases with increase in pressurewith increase in pressure
14 kg/cm14 kg/cm22, 210, 210ooC – 0.15046 mC – 0.15046 m33/kg/kg
16 kg/cm16 kg/cm22, 210, 210ooC – 0.12911 mC – 0.12911 m33/kg/kg
For Water specific volume does not change with increase in For Water specific volume does not change with increase in pressure, being an incompressible fluid.pressure, being an incompressible fluid.
100 kg/cm100 kg/cm22, 150, 150ooC – 0.00108 mC – 0.00108 m33/kg/kg
150 kg/cm150 kg/cm22, 150, 150ooC – 0.00108 mC – 0.00108 m33/kg/kg
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ALLOWABLE VELOCITYALLOWABLE VELOCITYALLOWABLE VELOCITYALLOWABLE VELOCITY
SELECTION OF THE MAXIMUM ALLOWABLE SELECTION OF THE MAXIMUM ALLOWABLE VELOCITY OF A FLUID IS IMPORTANT FROM VELOCITY OF A FLUID IS IMPORTANT FROM FOLLOWING POINTS OF CONSIDERATIONFOLLOWING POINTS OF CONSIDERATION
PRESSURE LOSS OF THE FLUID IN THE PRESSURE LOSS OF THE FLUID IN THE PIPE LINE (BEING DIRECTLY PIPE LINE (BEING DIRECTLY PROPORTIONAL TO SQUARE OF PROPORTIONAL TO SQUARE OF VELOCITY OF FLUID).VELOCITY OF FLUID).
EROSIONEROSION
VIBRATIONVIBRATION
PIPING CENTRE, CHENNAI
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ALLOWABLE VELOCITYALLOWABLE VELOCITYALLOWABLE VELOCITYALLOWABLE VELOCITY
ALLOWABLE VELOCITY SHOULD BE CHOSEN AS ALLOWABLE VELOCITY SHOULD BE CHOSEN AS PER GOOD DESIGN PRACTICE OR AS PER THE PER GOOD DESIGN PRACTICE OR AS PER THE GUIDELINES SPECIFIED FOR VARIOUS SYSTEMS BY GUIDELINES SPECIFIED FOR VARIOUS SYSTEMS BY
THE PROJECT CONSULTANT / CUSTOMERTHE PROJECT CONSULTANT / CUSTOMER..
PIPING CENTRE, CHENNAI
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ALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHEL
SUPERHEATED STEAM – 50 to 70 m/s SUPERHEATED STEAM – 50 to 70 m/s
(STEAM WITH PRESSURE GREATER THAN 50 kg/sqcm and (STEAM WITH PRESSURE GREATER THAN 50 kg/sqcm and TEMPERATURE GREATER THAN 400 DEG C)TEMPERATURE GREATER THAN 400 DEG C)
APPLICATIONS - MAIN STEAM, HOT REHEAT, COLD REHEAT, HP APPLICATIONS - MAIN STEAM, HOT REHEAT, COLD REHEAT, HP BYPASS U/s & LP BYPASS U/s BYPASS U/s & LP BYPASS U/s
LP BYPASS D/s & HP BYPASS D/s – 100 m/sLP BYPASS D/s & HP BYPASS D/s – 100 m/s
AUX STEAM (SATURATED) – 20 to 30 m/sAUX STEAM (SATURATED) – 20 to 30 m/s
(STEAM WITH PRESSURE LESS THAN 20 kg/sqcm and OPERATING (STEAM WITH PRESSURE LESS THAN 20 kg/sqcm and OPERATING TEMPERATURE VERY CLOSE TO SATURATION TEMPERATURE AT TEMPERATURE VERY CLOSE TO SATURATION TEMPERATURE AT THAT PRESSURE)THAT PRESSURE)
AUX STEAM (SUPERHEATED) – 30 to 40 m/sAUX STEAM (SUPERHEATED) – 30 to 40 m/s
(STEAM WITH PRESSURE LESS THAN 20 kg/sqcm and (STEAM WITH PRESSURE LESS THAN 20 kg/sqcm and TEMPERATURE 20-30 deg MORE THAN SATURATION TEMPERATURE 20-30 deg MORE THAN SATURATION TEMPERATURE AT THAT PRESSURE)TEMPERATURE AT THAT PRESSURE)
PIPING CENTRE, CHENNAI
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ALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHELALLOWABLE VELOCITY GUIDELINES USED IN BHEL
CONDENSATE DISCHARGE – 1.5 – 3 m/sCONDENSATE DISCHARGE – 1.5 – 3 m/s
BFP SUCTION – 1 – 1.5 m/sBFP SUCTION – 1 – 1.5 m/s
BFP DISCHARGE – 3-6 m/sBFP DISCHARGE – 3-6 m/s
COOLING WATER LINES – 1- 2 m/sCOOLING WATER LINES – 1- 2 m/s
PIPING CENTRE, CHENNAI
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STEAM (TEMPERATURE – ENTHALPY DIAGRAM)STEAM (TEMPERATURE – ENTHALPY DIAGRAM)STEAM (TEMPERATURE – ENTHALPY DIAGRAM)STEAM (TEMPERATURE – ENTHALPY DIAGRAM)
PIPING CENTRE, CHENNAI
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PIPING CENTRE, CHENNAI
PIPES ARE NORMALLY SPECIFIED BY PIPES ARE NORMALLY SPECIFIED BY THEIR OUTER DIAMETER IN MM AND THEIR OUTER DIAMETER IN MM AND THICKNESS IN MM . IN SOME SPECIAL THICKNESS IN MM . IN SOME SPECIAL CASES A PIPE IS SPECIFIED BY ITS CASES A PIPE IS SPECIFIED BY ITS INNER DIAMETER WHICH IS THEN INNER DIAMETER WHICH IS THEN CALLED AN ID CONTROLLED PIPE.CALLED AN ID CONTROLLED PIPE.
ASME STANDARD ASME B36.10 LISTS ASME STANDARD ASME B36.10 LISTS THE VARIOUS STANDARD OUTER THE VARIOUS STANDARD OUTER DIAMETERS AND THICKNESSES IN DIAMETERS AND THICKNESSES IN WHICH PIPES ARE MANUFACTUREDWHICH PIPES ARE MANUFACTURED
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PIPING CENTRE, CHENNAI
INCH NB OD STD XS XXS 10 20 30 40 60 80 100 120 140 1601/2 15 21.3 2.77 3.73 7.47 2.77 3.73 4.781 25 33.4 3.38 4.55 9.09 3.38 4.55 6.35
1-1/2 40 48.3 3.68 5.08 10.15 3.68 5.08 7.142 50 60.3 3.91 5.54 11.07 3.91 5.54 8.74
2-1/2 65 73 5.16 7.01 14.02 5.16 7.01 9.533 80 88.9 5.49 7.62 15.24 5.49 7.62 11.134 100 114.3 6.02 8.56 17.12 6.02 8.56 11.13 13.496 150 168.3 7.11 10.97 21.95 7.11 10.97 14.27 18.268 200 219.1 8.18 12.7 22.23 6.35 7.04 8.18 10.31 12.7 15.09 18.26 20.62 23.0110 250 273 9.27 12.7 25.4 6.35 7.8 9.27 12.7 15.09 18.26 21.44 25.4 28.5812 300 323.9 9.53 12.7 25.4 6.35 8.38 10.31 14.27 17.48 21.44 25.4 28.58 33.3214 350 355.6 9.53 12.7 6.35 7.92 9.53 11.16 15.09 19.05 23.83 27.79 31.75 35.7116 400 406.4 9.53 12.7 6.35 7.92 12.7 16.66 21.44 26.19 30.96 36.53 40.4918 450 457 9.53 12.7 6.35 7.92 11.13 14.27 19.05 23.83 29.36 34.93 39.67 45.2420 500 508 9.53 12.7 6.35 9.53 12.7 15.09 20.62 26.19 32.54 38.1 44.45 50.0122 550 559 9.53 12.7 6.35 9.53 12.7 22.23 28.58 34.93 41.28 47.63 53.9824 600 610 9.53 12.7 6.35 9.53 14.27 17.48 24.61 30.96 38.89 46.02 52.37 59.5426 650 660 9.53 12.7 7.92 12.728 700 711 9.53 12.7 7.92 12.7 15.8830 750 762 9.53 12.7 7.92 12.7 15.8832 800 813 9.53 12.7 7.92 12.7 15.88 17.4834 850 864 9.53 12.7 7.92 12.7 15.88 17.4836 900 914 9.53 12.7 7.92 12.7 15.88 19.0538 950 965 9.53 12.740 1000 1016 9.53 12.742 1050 1067 9.53 12.744 1100 1118 9.53 12.746 1150 1168 9.53 12.748 1200 1219 9.53 12.752 1300 1321 9.53 12.754 1350 1372 9.53 12.756 1400 1422 9.53 12.760 1500 1524 9.53 12.7
THICKNESS SCHEDULESDIAMETER
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PIPING CENTRE, CHENNAI
SELECT A PIPE OF DIAMETER GREATER SELECT A PIPE OF DIAMETER GREATER THAN THE CALCULATED ID.THAN THE CALCULATED ID.
THEN PROCEED TO DO THE THICKNESS THEN PROCEED TO DO THE THICKNESS CALCULATIONCALCULATION
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PIPING CENTRE, CHENNAI
THICKNESS OF THE PIPE WITH THICKNESS OF THE PIPE WITH SPECIFIED OUTER SPECIFIED OUTER DIAMETERDIAMETER IS CALCULATED USING THE FORMULA as per IS CALCULATED USING THE FORMULA as per
REG 350 OFREG 350 OF IBR IBR (INDIAN BOILER REGULATIONS CODE) (INDIAN BOILER REGULATIONS CODE)
T(MINIMUM) = P*D
(2*S*E+P)+ C
P – DESIGN PRESSURE IN KG/SQCM(G)
D – OUTER DIAMETER OF PIPE in mm
E – WELD JOINT EFFICIENCY FACTOR (1 FOR SEAMLESS PIPES, 0.8-0.95 FOR WELDED PIPES)
S – ALLOWABLE STRESS OF PIPE MATERIAL AS PER ASME SEC IID STANDARD in kg/cm2
C – COROSSION ALLOWANCE –0.75 mm
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PIPING CENTRE, CHENNAI
THICKNESS OF THE PIPE WITH THICKNESS OF THE PIPE WITH SPECIFIED INNER SPECIFIED INNER DIAMETERDIAMETER IS CALCULATED USING THE FORMULA as per IS CALCULATED USING THE FORMULA as per
REG 350 OFREG 350 OF IBR IBR (INDIAN BOILER REGULATIONS CODE) (INDIAN BOILER REGULATIONS CODE)
T(MINIMUM) = P*d
(2*S*E-P)
+ C
P – DESIGN PRESSURE IN KG/SQCM(G)
d – INNER DIAMETER OF PIPE in mm
E – WELD JOINT EFFICIENCY FACTOR (1 FOR SEAMLESS PIPES, 0.8-0.95 FOR WELDED PIPES)
S – ALLOWABLE STRESS OF PIPE MATERIAL AS PER ASME SEC IID STANDARD in kg/cm2
C – COROSSION ALLOWANCE –0.75 mm
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PIPING CENTRE, CHENNAI
THICKNESS OF THE PIPE WITH THICKNESS OF THE PIPE WITH SPECIFIED OUTER SPECIFIED OUTER DIAMETERDIAMETER IS CALCULATED USING THE FORMULA IS CALCULATED USING THE FORMULA as per as per ASME B31.1ASME B31.1
T(MINIMUM) = P*D
2*(S*E+P*y)+ A
P – DESIGN PRESSURE IN KG/SQCM(G)
D – OUTER DIAMETER OF PIPE in mm
E – WELD JOINT EFFICIENCY FACTOR (1 FOR SEAMLESS PIPES, 0.8-0.95 FOR WELDED PIPES)
S – ALLOWABLE STRESS OF PIPE MATERIAL AS PER ASME SEC IID STANDARD in kg/cm2
Y - FACTOR DEPENDING ON THE DESIGN TEMPERATURE, TO BE TAKEN FROM ASME B31.1
A – COROSSION ALLOWANCE –(1 OR 1.6 MM)
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PIPING CENTRE, CHENNAI
THICKNESS OF THE PIPE WITH THICKNESS OF THE PIPE WITH SPECIFIED INNER SPECIFIED INNER DIAMETERDIAMETER IS CALCULATED USING THE FORMULA IS CALCULATED USING THE FORMULA as per as per ASME B31.1ASME B31.1
T(MINIMUM) = P*d +2*S*E*A+2*P*y*A
2*(S*E+P*y - P)P – DESIGN PRESSURE IN KG/SQCM(G)
d – INNER DIAMETER OF PIPE in mm
E – WELD JOINT EFFICIENCY FACTOR (1 FOR SEAMLESS PIPES, 0.8-0.95 FOR WELDED PIPES)
S – ALLOWABLE STRESS OF PIPE MATERIAL AS PER ASME SEC IID STANDARD in kg/cm2
Y - FACTOR DEPENDING ON THE DESIGN TEMPERATURE, TO BE TAKEN FROM ASME B31.1
A – COROSSION ALLOWANCE –(1 OR 1.6 MM)
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Y- FACTOR AS PER ASME B 31.1Y- FACTOR AS PER ASME B 31.1Y- FACTOR AS PER ASME B 31.1Y- FACTOR AS PER ASME B 31.1
TEMP 0-482 DEG C – Y = 0.4TEMP 0-482 DEG C – Y = 0.4
AT TEMP 510 DEG C – Y = 0.5AT TEMP 510 DEG C – Y = 0.5
AT TEMP 540 DEG C & ABOVE – Y = 0.7AT TEMP 540 DEG C & ABOVE – Y = 0.7
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BASIS FOR THICKNESS FORMULABASIS FOR THICKNESS FORMULABASIS FOR THICKNESS FORMULABASIS FOR THICKNESS FORMULA
2r
dx
t
tConsider the fluid inside the pipe with pressure ‘p’ acting on a
small length dx of the pipe, h – the hoop stress arising due to the reaction
P*2*r dx = h * 2*t*dx
h = p*r / t
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DESIGN PRESSUREDESIGN PRESSUREDESIGN PRESSUREDESIGN PRESSURE
THE PIPING SYSTEM MUST BE DESIGNED TO SAFELY CONTAIN THE PIPING SYSTEM MUST BE DESIGNED TO SAFELY CONTAIN THE MAXIMUM POSSIBLE PRESSURE.THE MAXIMUM POSSIBLE PRESSURE.
FACTORS SUCH AS FAILURE OF CONTROL DEVICES, EVENTS FACTORS SUCH AS FAILURE OF CONTROL DEVICES, EVENTS LIKE SURGE, SAFETY RELIEF VALVES ETC SHOULD BE LIKE SURGE, SAFETY RELIEF VALVES ETC SHOULD BE CONSIDERED WHILE ARRIVING AT THE DESIGN PRESSURECONSIDERED WHILE ARRIVING AT THE DESIGN PRESSURE
DESIGN PRESSURE IS EXPRESSED IN KG/CMDESIGN PRESSURE IS EXPRESSED IN KG/CM22(G)(G)
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MAIN STEAM – SET PRESSURE OF SAFETY VALVE MAIN STEAM – SET PRESSURE OF SAFETY VALVE AT SUPER HEATER OUTLET.AT SUPER HEATER OUTLET.
HOT REHEAT – LOWEST SET PRESSURE OF SAFETY HOT REHEAT – LOWEST SET PRESSURE OF SAFETY VALVE AT REHEATER OUTLETVALVE AT REHEATER OUTLET
COLD REHEAT – MAXIMUM SET PRESSURE OF COLD REHEAT – MAXIMUM SET PRESSURE OF SAFETY VALVE AT REHEATER INLETSAFETY VALVE AT REHEATER INLET
BOILER FEED DISCHARGE – SHUT OFF HEAD OF AT BOILER FEED DISCHARGE – SHUT OFF HEAD OF AT MAXIMUM PUMP SPEED CORRESPONDING TO MIN MAXIMUM PUMP SPEED CORRESPONDING TO MIN RECIRCULATION FLOW.RECIRCULATION FLOW.
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DESIGN TEMPERATUREDESIGN TEMPERATUREDESIGN TEMPERATUREDESIGN TEMPERATURE
THE PIPING SYSTEM MUST BE DESIGNED FOR THE MAXIMUM THE PIPING SYSTEM MUST BE DESIGNED FOR THE MAXIMUM SUSTAINED TEMPERATURE OF THE MEDIUM.SUSTAINED TEMPERATURE OF THE MEDIUM.
DESIGN TEMPERATURE IS EXPRESSED IN DESIGN TEMPERATURE IS EXPRESSED IN ooCC
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ALLOWABLE STRESS OF THE MATERIALALLOWABLE STRESS OF THE MATERIALALLOWABLE STRESS OF THE MATERIALALLOWABLE STRESS OF THE MATERIAL
ALLOWABLE STRESS FOR THE MATERIAL FOR THE DESIGN ALLOWABLE STRESS FOR THE MATERIAL FOR THE DESIGN TEMPERATURE IS ADOPTED FROM THE ASME SEC IID TEMPERATURE IS ADOPTED FROM THE ASME SEC IID STANDARD. ALLOWABLE STRESS IS EXPRESSED IN KG/CMSTANDARD. ALLOWABLE STRESS IS EXPRESSED IN KG/CM2. 2. THE HOOP STRESS ON THE MATERIAL SHOULD BE LESS THAN THE HOOP STRESS ON THE MATERIAL SHOULD BE LESS THAN THE ALLOWABLE STRESS FOR THE TEMPERATURETHE ALLOWABLE STRESS FOR THE TEMPERATURE
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CRITERIA FOR ALLOWABLE STRESSCRITERIA FOR ALLOWABLE STRESSCRITERIA FOR ALLOWABLE STRESSCRITERIA FOR ALLOWABLE STRESS
ALLOWABLE STRESS IS THE LOWEST ALLOWABLE STRESS IS THE LOWEST OF THE FOLLOWING BELOW CREEP OF THE FOLLOWING BELOW CREEP TEMPERATURETEMPERATURE
Specified minimum tensile strength at room Specified minimum tensile strength at room temperature divided by 3.5temperature divided by 3.5
Tensile strength at service temperature Tensile strength at service temperature divided by 3.5divided by 3.5
2/3 of specified min yield strength at room 2/3 of specified min yield strength at room temperaturetemperature
2/3 of specified yield strength at service 2/3 of specified yield strength at service temperaturetemperature
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CRITERIAL FOR ALLOWABLE STRESSCRITERIAL FOR ALLOWABLE STRESSCRITERIAL FOR ALLOWABLE STRESSCRITERIAL FOR ALLOWABLE STRESS
ALLOWABLE STRESS IS THE LOWEST ALLOWABLE STRESS IS THE LOWEST OF THE FOLLOWING ABOVE CREEP OF THE FOLLOWING ABOVE CREEP TEMPERATURETEMPERATURE
100% of the average stress to produce a 100% of the average stress to produce a creep rate of 0.01% / 1000 hrscreep rate of 0.01% / 1000 hrs
67% of the average stress to cause rupture 67% of the average stress to cause rupture at the end of 100,000 hoursat the end of 100,000 hours
80% of minimum stress to cause rupture at 80% of minimum stress to cause rupture at the end of 100,000 hoursthe end of 100,000 hours
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HOOKE’S LAWHOOKE’S LAWHOOKE’S LAWHOOKE’S LAW
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CREEPCREEPCREEPCREEP
Creep is the term used to describe the Creep is the term used to describe the tendency of a material to deform tendency of a material to deform permanently at higher temperatures. permanently at higher temperatures. Material deformation occurs as a result of Material deformation occurs as a result of long term exposure to levels of stress that long term exposure to levels of stress that are below the yield or ultimate strength of are below the yield or ultimate strength of the material.The rate of this damage is a the material.The rate of this damage is a function of the material properties, function of the material properties, exposure time, exposure temperature and exposure time, exposure temperature and the applied load (stress). the applied load (stress).
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WALL THICKNESS CALCULATIONWALL THICKNESS CALCULATIONWALL THICKNESS CALCULATIONWALL THICKNESS CALCULATION
CALCULATE THE MINIMUM WALL CALCULATE THE MINIMUM WALL THICKNESS (TMIN) FOR THE PIPE FOR THICKNESS (TMIN) FOR THE PIPE FOR THE DESIGN CONDITIONS SUCH AS THE DESIGN CONDITIONS SUCH AS PRESSURE, TEMPERATURE AND PRESSURE, TEMPERATURE AND MATERIAL. DO THE MINIMUM WALL MATERIAL. DO THE MINIMUM WALL THICKNESS CALCULATION AS PER THICKNESS CALCULATION AS PER BOTH IBR AND ASME FORMULA AND BOTH IBR AND ASME FORMULA AND TAKE THE HIGHER VALUE.TAKE THE HIGHER VALUE.
ARRIVE AT THE NOMINAL WALL ARRIVE AT THE NOMINAL WALL THICKNESS (TNOM) BY ADDING THE THICKNESS (TNOM) BY ADDING THE PIPE MANUFACTURER’S TOLERANCE OF PIPE MANUFACTURER’S TOLERANCE OF (-12.5%) ON THE MINIMUM WALL (-12.5%) ON THE MINIMUM WALL THICKNESS – (TNOM = TMIN / 0.875)THICKNESS – (TNOM = TMIN / 0.875)
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WALL THICKNESS CALCULATIONWALL THICKNESS CALCULATIONWALL THICKNESS CALCULATIONWALL THICKNESS CALCULATION
SELECT A PIPE WITH WALL THICKNESS SELECT A PIPE WITH WALL THICKNESS HIGHER THAN THE NOMINAL WALL HIGHER THAN THE NOMINAL WALL THICKNESS, FROM THE ASME B36.10 THICKNESS, FROM THE ASME B36.10 STANDARD OR RATIONALIZED LIST OF STANDARD OR RATIONALIZED LIST OF PIPES.PIPES.
CALCULATE THE ID OF THE SELECTED CALCULATE THE ID OF THE SELECTED PIPE. IF THE ID IS GREATER THAN THE PIPE. IF THE ID IS GREATER THAN THE CALCULATED ID , SELECTION IS OK, CALCULATED ID , SELECTION IS OK, OTHER WISE SELECT THE NEXT HIGHER OTHER WISE SELECT THE NEXT HIGHER OD AND REPEAT THE PIPE THICKNESS OD AND REPEAT THE PIPE THICKNESS CALCULATION.CALCULATION.
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SAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATION
AUXILIARY STEAM LINE TO SCAPHAUXILIARY STEAM LINE TO SCAPH
FLOW = 32 T/HRFLOW = 32 T/HR
OPERATING PRESSURE = 16 kg/cmOPERATING PRESSURE = 16 kg/cm22(a)(a)
OPERATING TEMPERATURE = 210OPERATING TEMPERATURE = 210ooCC
DESIGN PRESSURE = 20 kg/cmDESIGN PRESSURE = 20 kg/cm22(g)(g)
DESIGN TEMPERATURE = 210DESIGN TEMPERATURE = 210ooCC
MATERIAL = SA106GRBMATERIAL = SA106GRB
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CALCULATION OF IDCALCULATION OF IDCALCULATION OF IDCALCULATION OF ID
THE SATURATION TEMPERATURE THE SATURATION TEMPERATURE CORRESPONDING TO 16 kg/cmCORRESPONDING TO 16 kg/cm22(a) is (a) is 200200ooC. SINCE THE DEGREE OF C. SINCE THE DEGREE OF SUPERHEAT (OPERATING TEMP- SAT SUPERHEAT (OPERATING TEMP- SAT TEMP = 210-200= 10TEMP = 210-200= 10ooC) IS LESS THAN C) IS LESS THAN 2020ooC, THE MAX ALLOWABLE VELOCITY C, THE MAX ALLOWABLE VELOCITY IS 30 m/sIS 30 m/s
SPECIFIC VOLUME CORRESPONDING TO SPECIFIC VOLUME CORRESPONDING TO 16 kg/cm16 kg/cm22(g) AND 210(g) AND 210ooC is 0.12991 MC is 0.12991 M33/KG./KG.
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CALCULATION OF IDCALCULATION OF IDCALCULATION OF IDCALCULATION OF ID
ID = 595*SQRT(flow*spvol/velocity)ID = 595*SQRT(flow*spvol/velocity)
ID = 595*SQRT(32*0.12991/30)
ID = 221.49 mm
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SELECTION OF ODSELECTION OF ODSELECTION OF ODSELECTION OF OD
SELECT NEAREST STANDARD OD SELECT NEAREST STANDARD OD GREATER THAN 221.49 mm, NEAREST GREATER THAN 221.49 mm, NEAREST OD IS 273 mm. OD IS 273 mm.
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ALLOWABLE STRESSALLOWABLE STRESSALLOWABLE STRESSALLOWABLE STRESS
ALLOWABLE STRESS OF SA106GRB ALLOWABLE STRESS OF SA106GRB MATERIAL AT 210MATERIAL AT 210ooC IS 1202.24 kg/cmC IS 1202.24 kg/cm22
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SELECTION OF MINIMUM WALL THICKNESSSELECTION OF MINIMUM WALL THICKNESSSELECTION OF MINIMUM WALL THICKNESSSELECTION OF MINIMUM WALL THICKNESS
T(MINIMUM) = P*D T(MINIMUM) = P*D
(2*S*E+P)(2*S*E+P)+ C
T(MINIMUM) = 20*273
(2*1202.24*1+20)
+ 0.75
AS PER IBR
T(MIN)- IBR = 3.00 mm
T(MINIMUM) = P*D
2*(S*E+P*y)
AS PER ASME
+ A
T(MINIMUM) = 20*273
2*(1202.24*1+20*0.4)+ 1.6 T(MIN) - ASME = 3.86 mm
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SELECTION OF NOMINAL WALL THICKNESSSELECTION OF NOMINAL WALL THICKNESSSELECTION OF NOMINAL WALL THICKNESSSELECTION OF NOMINAL WALL THICKNESS
SELECT THE GREATER VALUE OF THE MINIMUM SELECT THE GREATER VALUE OF THE MINIMUM WALL THICKNESS FROM THE CALCULATIONS WALL THICKNESS FROM THE CALCULATIONS USING IBR AND ASME FORMULAE – USING IBR AND ASME FORMULAE –
TMIN = 3.86 mm (GREATER OF 3.00,3.86)TMIN = 3.86 mm (GREATER OF 3.00,3.86)
TNOM = TMIN / (1- NEGATIVE TOLERANCE) TNOM = TMIN / (1- NEGATIVE TOLERANCE)
NEGATIVE TOLERANCE = 12.5%NEGATIVE TOLERANCE = 12.5%
TNOM = 3.86 / (1-0.125) = 3.86 / 0.875 = 4.41TNOM = 3.86 / (1-0.125) = 3.86 / 0.875 = 4.41
SELECT A PIPE WITH WALL THICKNESS GREATER SELECT A PIPE WITH WALL THICKNESS GREATER THAN 4.41 mm FROM B36.10THAN 4.41 mm FROM B36.10
PIPE WITH WALL THICKNESS 6.35 mm (SCH 10) is PIPE WITH WALL THICKNESS 6.35 mm (SCH 10) is SELECTEDSELECTED
SELECTED PIPE IS OF OD 273 AND WALL SELECTED PIPE IS OF OD 273 AND WALL THICKNESS 6.35 MMTHICKNESS 6.35 MM
41
CHECK FOR IDCHECK FOR IDCHECK FOR IDCHECK FOR ID
ID REQUIRED AS PER FORMULA = 221.49 ID REQUIRED AS PER FORMULA = 221.49 mmmm
ID OF SELECTED PIPE OD 273 X 6.35 = ID OF SELECTED PIPE OD 273 X 6.35 = 273 – 2*6.35 = 260.3 mm273 – 2*6.35 = 260.3 mm
260.3 mm > 221.49 mm, HENCE 260.3 mm > 221.49 mm, HENCE SELECTED PIPE IS OK. (ID OF SELECTED SELECTED PIPE IS OK. (ID OF SELECTED PIPE SHOULD BE GREATER THAN PIPE SHOULD BE GREATER THAN CALCULATED ID)CALCULATED ID)
42
PRESSURE DROP CALCULATIONPRESSURE DROP CALCULATIONPRESSURE DROP CALCULATIONPRESSURE DROP CALCULATION
43
PRESSURE LOSS IN STRAIGHT PIPESPRESSURE LOSS IN STRAIGHT PIPESPRESSURE LOSS IN STRAIGHT PIPESPRESSURE LOSS IN STRAIGHT PIPES
PRESSURE LOSS IN PIPES IS GIVEN BY THE PRESSURE LOSS IN PIPES IS GIVEN BY THE DARCY-WEISBACH EQUATIONDARCY-WEISBACH EQUATION
p = ( f*l/d)*(vp = ( f*l/d)*(v22/2g)*(1/10000)* /2g)*(1/10000)* p = Pressure Loss in kg/cmp = Pressure Loss in kg/cm22
f = DARCY FRICTION FACTORf = DARCY FRICTION FACTOR
l = LENGTH OF PIPE IN METRESl = LENGTH OF PIPE IN METRES
d = INNER DIAMETER OF PIPE IN METRESd = INNER DIAMETER OF PIPE IN METRES
v = VELOCITY OF FLUID IN M/Sv = VELOCITY OF FLUID IN M/S
g = ACCELERATION DUE TO GRAVITY In m/sg = ACCELERATION DUE TO GRAVITY In m/s22 – – 9.81 m/s9.81 m/s22
= DENSITY IN kg/m= DENSITY IN kg/m33
44
FRICTION FACTOR FOR PIPESFRICTION FACTOR FOR PIPESFRICTION FACTOR FOR PIPESFRICTION FACTOR FOR PIPES
DARCY FRICTION FACTOR = 4 * MOODY DARCY FRICTION FACTOR = 4 * MOODY FRICTION FACTORFRICTION FACTOR
(mm)
= Absolute Pipe Roughness in mm = 0.05 for Steel Pipe
d = Inner Diameter of Pipe in mm
Re = Reynolds Number
f = Moody Friction Factor
The Barr Equation
89.010 Re
1286.5
71.3log4
1
df
2
89.010 Re
1286.5
71.3log41
df
45
REYNOLDS NUMBERREYNOLDS NUMBERREYNOLDS NUMBERREYNOLDS NUMBER
REYNOLDS NUMBER IS A REYNOLDS NUMBER IS A DIMENSIONLESS NUMBER CALCULATED DIMENSIONLESS NUMBER CALCULATED BY THE FOLLOWING FORMULABY THE FOLLOWING FORMULA
Re = Re = *V*d/*V*d/ = DENSITY OF FLUID IN kg/m= DENSITY OF FLUID IN kg/m33
V = VELOCITY OF FLUID IN m/sV = VELOCITY OF FLUID IN m/s
d = INNER DIA OF PIPE IN mmd = INNER DIA OF PIPE IN mm
= ABSOLUTE VISCOSITY IN CENTIPOISE = ABSOLUTE VISCOSITY IN CENTIPOISE (cP) (CENTIPOISE = VISCOSITY IN KG/M-S (cP) (CENTIPOISE = VISCOSITY IN KG/M-S *1000 )*1000 )
46
REYNOLDS NUMBERREYNOLDS NUMBERREYNOLDS NUMBERREYNOLDS NUMBER
IF THE REYNOLDS NUMBER < 2000, IF THE REYNOLDS NUMBER < 2000, FLOW IS LAMINARFLOW IS LAMINAR
IF THE REYNOLDS NUMBER > 4000 IF THE REYNOLDS NUMBER > 4000 FLOW IS TURBULENTFLOW IS TURBULENT
47
FRICTION FACTOR FOR FITTINGSFRICTION FACTOR FOR FITTINGSFRICTION FACTOR FOR FITTINGSFRICTION FACTOR FOR FITTINGS
THE RESISTANCE TO FLOW OF FLUIDS THE RESISTANCE TO FLOW OF FLUIDS IN FITTINGS IS GIVEN BY A RESISTANCE IN FITTINGS IS GIVEN BY A RESISTANCE FACTOR ‘K’.FACTOR ‘K’.
K = f*(Leq/D)K = f*(Leq/D)
F = DARCY FRICTION FACTORF = DARCY FRICTION FACTOR
Leq = EQUIVALENT LENGTH OF FITTINGLeq = EQUIVALENT LENGTH OF FITTING
D = INNER DIAMETER OF PIPE IN D = INNER DIAMETER OF PIPE IN METRESMETRES
48
(Leq/D) for FITTINGS(Leq/D) for FITTINGS(Leq/D) for FITTINGS(Leq/D) for FITTINGS
(Leq/D) FOR VARIOUS FITTINGS IS (Leq/D) FOR VARIOUS FITTINGS IS OBTAINED FROM CRANES HANDBOOK OBTAINED FROM CRANES HANDBOOK OF FLOW OF FLUIDSOF FLOW OF FLUIDS
FITTING (Leq/D)
ELBOW 14
RUN TEE 20
BRANCH TEE 60
RESISTANCE FACTOR K = f * (Leq/D)
PRESSURE LOSS IN FITTINGS K = f * (Leq/D)
49
RESISTANCE FACTOR DIRECTLY GIVENRESISTANCE FACTOR DIRECTLY GIVENRESISTANCE FACTOR DIRECTLY GIVENRESISTANCE FACTOR DIRECTLY GIVEN
RESISTANCE FACTOR FOR FITTINGS RESISTANCE FACTOR FOR FITTINGS LIKE VALVES CAN BE DIRECTLY LIKE VALVES CAN BE DIRECTLY OBTAINED FROM CATALOGUES OBTAINED FROM CATALOGUES INSTEAD OF (Leq/D) METHODINSTEAD OF (Leq/D) METHOD
FITTING K
GATE VALVE – 10” 0.182
NON RETURN VALVE – 10”
0.98
50
SAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATION
FIND THE PRESSURE DROP IN THE FOLLOWING FIND THE PRESSURE DROP IN THE FOLLOWING PIPE. ALLOWED PRESSURE DROP IS 3 kg/cmPIPE. ALLOWED PRESSURE DROP IS 3 kg/cm22
PIPE SIZE – OD 273 X 28 (ID = 273-2*28 = 217 mm)PIPE SIZE – OD 273 X 28 (ID = 273-2*28 = 217 mm)
FLOW – 150 T/HRFLOW – 150 T/HR
PRESSURE AT OUTLET OF BOILER – 90kg/cmPRESSURE AT OUTLET OF BOILER – 90kg/cm22(a)(a)
TEMPERATURE AT OUTLET OF BOILER – 515 deg CTEMPERATURE AT OUTLET OF BOILER – 515 deg C
SPVOL = 0.03174 mSPVOL = 0.03174 m33/kg/kg
DENSITY = (1/SPVOL) = 25.99 kg/mDENSITY = (1/SPVOL) = 25.99 kg/m33
VISCOSITY = 0.029 cPVISCOSITY = 0.029 cP
51
SAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATIONSAMPLE CALCULATION
LENGTH OF PIPE – 65 metresLENGTH OF PIPE – 65 metres
FITTINGS IN THE LINEFITTINGS IN THE LINE
90 deg LR Elbow – 14 Nos90 deg LR Elbow – 14 Nos
Gate Valve – 1 NoGate Valve – 1 No
Run Tee – 2 NosRun Tee – 2 Nos
Flow Nozzle (Fixed Pressure Drop – 0.3 Flow Nozzle (Fixed Pressure Drop – 0.3 kg/cmkg/cm22))
52
CALCULATION OF VELOCITYCALCULATION OF VELOCITYCALCULATION OF VELOCITYCALCULATION OF VELOCITY
VELOCITY OF FLUIDVELOCITY OF FLUID
ID = 595*SQRT(flow*spvol/velocity)
ID2 = 595*595*(flow*spvol/velocity)
velocity = 595*595*(flow*spvol/ID2)
velocity = 595*595*(150*0.03174/2172)
velocity = 43.39 m/s
53
CALCULATION OF REYNOLDS NUMBERCALCULATION OF REYNOLDS NUMBERCALCULATION OF REYNOLDS NUMBERCALCULATION OF REYNOLDS NUMBER
Re = Re = *V*d/*V*d/
Re = 25.99*43.39*217/0.029Re = 25.99*43.39*217/0.029
Re = 8438353Re = 8438353
54
CALCULATION OF MOODY FRICTION FACTORCALCULATION OF MOODY FRICTION FACTORCALCULATION OF MOODY FRICTION FACTORCALCULATION OF MOODY FRICTION FACTOR
f = 1/[-4*log10(0.05/3.71*217 + 5.1286/(8438353)0.89)]2
The Barr Equation
89.010 Re
1286.5
71.3log4
1
df
2
89.010 Re
1286.5
71.3log41
df
f = 1/[-4*log10(6.56*10-5)]2
f = 1/ [-4*- 4.18]2
f = 1/ 279.95
f = 0.00357
Darcy Friction Factor = 4*f = 0.01428
55
TOTAL PRESSURE DROPTOTAL PRESSURE DROPTOTAL PRESSURE DROPTOTAL PRESSURE DROP
PRESSURE DROP IS STRAIGHT PIPE + PRESSURE DROP IS STRAIGHT PIPE + PRESSURE DROP IN PRESSURE DROP IN FITTINGS+PRESSURE DROP IN FITTINGS+PRESSURE DROP IN VALVES+PRESSURE DROP IN FLOW VALVES+PRESSURE DROP IN FLOW NOZZLENOZZLE
56
CALCULATION OF PRESSURE LOSS IN CALCULATION OF PRESSURE LOSS IN STRAIGHTPIPESTRAIGHTPIPE
CALCULATION OF PRESSURE LOSS IN CALCULATION OF PRESSURE LOSS IN STRAIGHTPIPESTRAIGHTPIPE
p = ( f*l/d)*(vp = ( f*l/d)*(v22/2g)* /2g)* *(1/10000)*(1/10000)
p = (0.01428*67/0.217)*(43.39p = (0.01428*67/0.217)*(43.3922/2*9.81)*25.99* /2*9.81)*25.99* (1/10000)(1/10000)
p = 1.06 kg/cmp = 1.06 kg/cm22
57
PRESSURE LOSS IN FITTINGSPRESSURE LOSS IN FITTINGSPRESSURE LOSS IN FITTINGSPRESSURE LOSS IN FITTINGS
90 DEG LR ELBOW = 14 NOS90 DEG LR ELBOW = 14 NOS
RUN TEE = 2 NOSRUN TEE = 2 NOS
Leq/D FOR ONE ELBOW = 14Leq/D FOR ONE ELBOW = 14
Leq/D FOR ONE RUN TEE = 20Leq/D FOR ONE RUN TEE = 20
TOTAL Leq/D FOR FITTINGS = 14*14+2*20 = 236TOTAL Leq/D FOR FITTINGS = 14*14+2*20 = 236
TOTAL RESISTANCE K = f*Leq/DTOTAL RESISTANCE K = f*Leq/D
K = 0.01428*236 = 3.37K = 0.01428*236 = 3.37
FRICTION LOSS = K*(VFRICTION LOSS = K*(V22/2g)* /2g)* *(1/10000)*(1/10000)
FRICTION LOSS = 3.37*(43.39FRICTION LOSS = 3.37*(43.3922/2*9.81)*25.99* (1/10000)/2*9.81)*25.99* (1/10000)
FRICTION LOSS IN FITTINGS = 0.84 kg/cmFRICTION LOSS IN FITTINGS = 0.84 kg/cm22
58
PRESSURE LOSS IN VALVESPRESSURE LOSS IN VALVESPRESSURE LOSS IN VALVESPRESSURE LOSS IN VALVES
RESISTANCE FACTOR FOR GATE VALVE RESISTANCE FACTOR FOR GATE VALVE NB 250 = 0.182NB 250 = 0.182
K = 0.182K = 0.182
FRICTION LOSS = K*(VFRICTION LOSS = K*(V22/2g)* /2g)* *(1/10000)*(1/10000)
FRICTION LOSS = 0.182*(43.39FRICTION LOSS = 0.182*(43.3922/2*9.81)*25.99* (1/10000)/2*9.81)*25.99* (1/10000)
FRICTION LOSS IN GATE VALVE = 0.045 kg/cmFRICTION LOSS IN GATE VALVE = 0.045 kg/cm22
59
PRESSURE LOSS IN FLOW NOZZLEPRESSURE LOSS IN FLOW NOZZLEPRESSURE LOSS IN FLOW NOZZLEPRESSURE LOSS IN FLOW NOZZLE
FRICTION LOSS IN FLOW NOZZLE = 0.3 FRICTION LOSS IN FLOW NOZZLE = 0.3 kg/cmkg/cm2 2
60
TOTAL PRESSURE DROPTOTAL PRESSURE DROPTOTAL PRESSURE DROPTOTAL PRESSURE DROP
PRESSURE DROP IS STRAIGHT PIPE + PRESSURE DROP IN FITTINGS+PRESSURE DROP IN VALVES+PRESSURE DROP IN FLOW NOZZLE
TOTAL PRESSURE DROP = 1.06+0.84+0.05+0.3 = 2.25 kg/cm2
61
CHECK FOR ALLOWED DROPCHECK FOR ALLOWED DROPCHECK FOR ALLOWED DROPCHECK FOR ALLOWED DROP
SINCE TOTAL PRESSURE DROP OF 2.25 SINCE TOTAL PRESSURE DROP OF 2.25 kg/sqcm IS LESS THAN ALLOWED kg/sqcm IS LESS THAN ALLOWED PRESSURE DROP OF 3 kg/sqcm, THE PRESSURE DROP OF 3 kg/sqcm, THE SELECTED PIPE SIZE IS OK.SELECTED PIPE SIZE IS OK.