Hydraulic Calculation Lecture-Piping I

Mar.2006Novin Parsian Co.

Hydraulic calculation in piping networks(Piping Training Courses)

Author:Armin Eftekhari


Introduction of the trainer

Armin Eftekhari

§ Marital status : Married§ Age : 34 years ( 8th Sep. 1972)§ Place of Birth : Tehran§ M.S. in Mechanical Engineering (Applied Mechanics)[ Sep.1995 ~ Sep.1998 ] Azad University of Tehran§ B.S. in Mechanical Engineering (Solid Mechanics)[ Sep.1990 ~ Jan.1995 ] Azad University of Tehran [ Sep. 2000 until now ] Montreal Consulting Engineering Company(Tehran / Iran)

Designer of piping & auxiliary systems of power plants§ Design of design criteria, system description, Process Flow Diagram, Piping & instrumentation diagram, General & equipment arrangement, Pipe route, Pipinglayout, Isometric, Input for civil work Drawing, Piping specification, Insulationspecification, Preparation of line list, valve list, equipment list, stress analysis,MTO(Material take off), supporting, sizing &pressure drop calculation of thefollowing systems :§ Natural gas system§ Gas oil system§ Auxiliary cooling system§ Compressed air system§ Lube oil system

Personal Information

Education

Professional experience

Example 1

Sequence Of Simulation

COMPRESSIBLE FLOW IN

PIPING

Pipe Sizing Calculations

Requirements & contract

Recommendations

Pressure drop

Velocity

Sizing Criteria

Hydraulic Calculation Definition

Network inlet & outlet

Labeling Diagram

Piping Network

Topics

Introduction of trainer


Introduction of the trainer

Armin Eftekhari

§ Production & Supply water system§ Air conditioning system§ Plumbing System§ Chemical drain & sewage systemMechanical Cordinator§ Kazeroon Gas Turbine Power Plants§ Damavand Gas Turbine Power Plants§ Sanadaj Gas Turbine Power Plants§ Shirvan Gas Turbine Power PlantsHead Of piping GroupWorking with the following soft wares:Windows 2000 / XP ,Word , Excel, Access, Power point, Front PageAuto cad , Microstation ,Caesar II, Cadworx , Pipe net, Trace calculator , Insulation calculator,PDSWorking with the following Computer languages:Matlab, Qbasic,Fortran

Trainings Excel, Cadworx, Caesar II ,Micro station,Siemens technology transfer for combined cycles(Equipment & General Modules)English( fluent in specking, Reading & writing)Farsi(Native Language)

Languages

Professional experience

Additional professional skills

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Schedule

TopicsTopics

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics


1- Piping Network

2- Labeling Diagram

3- Inlets and Outlets

4- Hydraulic Calculation

5- Sizing Criteria 5.1- Velocity 5.2- Pressure drop 5.3- System requirements & contract (client) recommendations

6- Pipe sizing calculation

7- Steady single phase compressible & incompressible flow in piping systems

8- Sequence of simulation

9- Example #1

10- Example #2

11-Introduction of pipe net Software


Basic Definitions

1- Piping Network

In general, networks consist of a number of components (Pipes, Ducts, Pumps, Valves, Filters, Orifice Plates, Fixed Pressure Drops and Nozzles) all connected together. The points at which the components may be joined to other components are referred to as nodes. Consider, for example, the simple system shown below, which consists of a single pipe with a nozzle on one end. A fluid enters at theopen end of the pipe and is discharged through the nozzle.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Basic Definitions

This network can be represented schematically by the diagram shown below.

2- Labeling Diagram

Notice how the pipe, nozzle and nodes have each been given a label. When preparing a network for simulation every component and every node must be given a label which identifies it uniquely. The production of a fully labelled schematic diagram is an essential part of any simulation.Labels may either be tagged or untagged.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Basic Definitions

Labels can be tagged or untagged.Tags can be used to make labels more meaningful, and to allow sections of large networks to be more easily identified. In our schematic diagram we have labeled the pipe as P/1(tagged label), the nozzle as 100(untaged label), and the nodes as 1 and 2(untaged label).

3- Inlets and Outlets

In the drawing of a network ,each pipe, pump, valve and filter component should have two nodes (one at each end). One of these nodes is designated the component's input node and the other is designated its output node. Note that fluid does not necessarily flow from the input node to the output node.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Sizing

4- Hydraulic Calculation

-Sizing calculation.

-Pressure Drop calculation.

-Adjust/Regulate/Control of the piping systems.

5- Sizing Criteria

1-Velocity.

2-Pressure drop.

3-System requirements and contract (client) recommendations.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Sizing

5.1- Velocity

High velocity in piping systems increases the following effects:

-Pressure Drop.

-Pipe corrosion.

-Water hammer.

-Noise (sound) emission.

In the other hand low velocities increases pipe diameter (Increase the total cost) and also increase the possibility of illuviation (Sedimentation) in a piping systems.

For fluid velocities of different systems it is better to refer to the piping hand books.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Basic Definitions

5.2- Pressure drop

Generally if is preferable to reduce pressure drop in piping system as far as possible because :

-To decreases the size of pump or compressor (Cost reduction).

-To reduces the initial pressure (i.e. in case of gravity flows).

-To decreases the energy losses.

-To reduce down stream velocity of gases and also the related corrosion and noise emission.

For admissible pressure drop for different media system it is better to refer to piping hand books (For example for Water it is 2.5 m/100m and for natural gas the total pressure drop shall be less than 10% of initial pressure).

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Basic Definitions

5.3 -System requirements & contract (client) recommendations

Some times we have to meet some conditions in Terminal points / input/out put points (according to technical matters, contract specifications or client requirements). For example:

- For a long water piping system with gravity flow may be it is needed to use velocities less than what was mentioned before.

- For a system with predefined flow characteristics in inlet and out let points (flow characteristics have been defined in terminal points).

-Climatic conditions.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Sizing

6- Pipe sizing calculation

Suppose that a pipe shall deliver a media with density of and flow rate of m’ then :

Hence :

or

000

0

QmQm

×=⇒= ρρ

VAQ ×=0

2

4 iDA π=

VDm i ××= 20

4πρ

VQDi ×

=π

0

2V

mDi ××=

πρ

0

2

ρ

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Sizing

Where; Liquid Density [kg/m³] , m’=mass flow rate [kg/s] ,

Q’=Volumetric flow rate [m³/s] , A=Pipe cross section area [m²] ,

V=Admissible flow velocity (to be taken from the table) [m/s] ,

Internal pipe diameter [m]

After calculation of the pipe inside diameter ,according to the pipe schedule and pipe dimension standard the suitable nominal diameter is selected.

Now the actual velocity of the medium in the pipe shall be calculated according to the selected nominal diameter.

Note: The metal pipe dimensions are basically according to ANSI B36.10 or API 5L.Also for PE pipe please refer to DIN 8074.

=ρ

=iD

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of fluids

7- STEADY SINGLE-PHASE COMPRESSIBLE FLOW IN PIPING

According to Darcy formula , the friction head loss in an incompressible fluid is calculated from the following formula :

Where ;

Friction Head loss [m] Darcy Friction Factor

L=Pipe Length [m] , Liquid Density [kg/m3] , V=Fluid velocity [m/s]

Internal Diameter Of pipe [m] , g=Gravity acceleration [9.81 m/s²]

2

2VDLfP

if ×××=∆⇒ ρg

VDLfH

if 2

2

×=

ff HgP ××=∆ ρ

=fH =f

=ρ

=iD

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of fluids

The Darcy friction factor is obtained from the following formula :

(for laminar flow : Re<2000 )

Expressions for calculating the loss of pressure in turbulent flow are based upon experimental data. For complete turbulence zone (Re>3000) the following has been developed by Colebrook:

Where : Roughness [mm] , Re=Reynolds No.=

Fluid viscosity [cp]

For transitional flow (2000<Re<3000)f is found by interpolating between laminar value for Re=2000 and turbulent value at Re=3000.

Re64

=f

)Re

252.127.0(768.11fD

Lnf i

+×−=ε

=εµ

ρ iVD

=µ

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of fluids

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of fluids

Pressure losses which occur in piping systems due to bends, elbows, joints, valves, and so forth are called form losses. For the recommended values of local flow resistance coefficients (K-factors) please refer to Crane Flow of Fluids.

Where; Liquid Density [kg/m3] , V=Fluid velocity [m/s]

Head loss due to the fittings [m] , K=Fittings resistance coefficient

Pressure drop due to fittings [Pascal]

Form losses may also be expressed in terms of the equivalent length Le of pipe that has the same pressure head loss for the same flow rate; thus

22

22 VKPg

VKH fittingsfittings ××=∆⇒×= ρ

=ρ

=fittingsH

=∆ fittingsP

fDKL

gVK

gV

DLf i

ei

e =⇒×=×22

22

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of fluids

With this formula according to k factor of each fitting the relevant equivalent length will be obtained. For quick calculations a chart has been provided in Crane Flow of fluids.

The pressure loss due to elevation changes in a pipe section will be calculated by the following formula :

Hence the total pressure drop of a piping system will be obtained as follow :

Where is belong to any other equipment or accessory in the system.

)( 12 zzgPstatic −=∆ ρ

otheresstaticfittingsfrictiontotal PPPPP ∆+∆+∆+∆=∆

otheresP∆

othersi

total PzzgVKDLfP ∆+−++=∆ )(

2)( 12

2

ρρ

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of Fluids

8- Sequence of simulation

-Prepare a pipe route (single line) according to the technical specification and system requirements.

-Specify the process characteristics of flow in I/O points (Regarding to the Terminal point data, consumers and also system component specifications)

-Specify each pipe section and its node numbers and extract its relevant information from the pipe route and technical specifications (length of the pipe section, its start & end nodes identification, its fitting, fixed pressure drops,…).

-Calculate the pipe size of each pipe section (see page 12).

-Calculate the total pressure drop in each pipe section. It is noted that out put pressure of each pipe section shall be used as input pressure of the next pipe section.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Flow of Fluids-Example 1

-The total pressure drop is the difference between inlet pressure of the first pipe section and outlet pressure of the farthest pipe section.

Example #1 : Please specify the pressure of out put points (consumers) for the water distribution system in the next page. It is noted that according to piping specification of contract the pipe schedule for all size shall be Sch. STD commercial pipe and water temp is 15ºc.Also according to the strainer data sheet the maximum pressure drop of the strainer at dirty condition is 0.2 bar. Regarding to the piping specification All the bends are long radius (R=1.5D). The minimum pressure in inlet terminal point is 8 barg .The elevation of the inlet terminal point is 800 MSL.

Solution :

Step 1 & 2: Regarding to the technical specification and I/O process characteristics a pipe route has been prepared in the next page.Step 3:In sheet after each pipe section and its relevant nodes has been identified.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Tee branch : 1 Ball valve : 1

Tee run : 1 90º Elbow : 1

Globe valve : 1

Tee branch : 1 90º Elbow : 1

Tee branch : 1 90º Elbow : 1

Globe valve : 1

90º Elbow : 1 Gate valve : 1 check valve :1

List of Fittings

-681180564P/55

-7279880554P/44

0.2 (Strainer)16580580542P/33

-18080580532P/22

-3580580021P/11

Other pressure loss [bar]

Length [m]

Out put node

elevation [m]

Input node

elevation [m]

Out put node

Input node

Pipe SectionItem

Piping geometry information

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Pipe size calculation :

For pipe section P/1:Q’=235 m³/h , V = 3 m/s (Acc. To the admissible velocity)Hence:

Pipe sch. is STD. There fore according to the standard dimension the Nominal Diameter is selected:

DN 150 , Sch STD →Di = 154.08 mm

DN 200 , Sch STD →Di = 202.74 mm

→DN 200(Sch. STD) selected. →Di=202.74

mmD

mV

QD

i

i

166

166.03

3600/235220

=

=×

=×

=ππ

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




→ (actual velocity)

In the same way the size of the other pipe sections obtained as follow:

For pipe section P/2:Q’=80 m³/h , V = 3 m/s Hence: Di=0.097 →DN 100(Sch. STD) selected. →Di=102.26 mm ,V=2.706 m/s




Now all of the pipe section has sized. Next step is pressure drop calculation.

smVD

QVi

/022.24/ 2

0

=→×

=π

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




For pipe section P/1: pipe size is DN 200 then according to table A26 of Crane hand book pipe friction factor is obtained :

The fittings are :

90º Elbow : 1 → (From table A29)

Gate valve : 1 → (From table A27)

check valve :1 → (From table A27)

→

The roughness of the commercial steel pipes is 0.0457mm,hence the relative roughness will be calculated as follow :

014.0=Tf

196.0014.01414 11 =⇒×=×= KfK T

112.0014.088 12 =⇒×=×= KfK T

4.1014.0100100 13 =⇒×=×= KfK T

708.1321 =→++= KKKKK

000225.074.202

0457.0===

iDRR ε

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




The Reynolds number is :

By referring to Darcy friction factor chart (see page 16) The Darcy friction Factor is obtained :

By reviewing pipe section geometry information it is seen that the input node elevation is 800m and out put node elevation is 805.

The total pressure loss of the first pipe section will be :

In the same way the pressure drop of the other pipe sections obtained as follow:

53

10095.4.001.0

20274.0/022.2/999Re ×=××

==sPas

msmmkgVDµ

ρ

0151.0=f

Pascal6.57671)800805(81.9999 =−××+2

022.2)708.120274.0350151.0(999)(

2)(

2

12

2

×+×=−++=∆ zzgVKDLfP

itotal ρρ

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




67765.4

-24821.2

50010.9

141627.7

57671.6

Total Pressure

Drop [Pascal]

0.6780.01922.040x100,0000.0005861.134P/55

-0.2480.01723.031x100,0000.0003565.984P/44

0.5000.01653.554x100,0000.0002971.11P/33

1.4160.01802.764 x100,0000.0004477.038P/22

0.5760.01474.095x100,0000.0002251.708P/11

Total Pressure

Drop [bar]

Darcy Pipe

Friction Factor

Reynolds Number

Relative Roughness

Fittings K Factor

Pipe SectionItem

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




As it is seen from the Pipe nodes arrangement :

2#sec1#sec1#3# tionpipetionpipenodenode PPPP −− ∆−∆−=

5#sec3#sec1#sec1#6# tionpipetionpipetionpipenodenode PPPPP −−− ∆−∆−∆−=

4#sec3#sec1#sec1#5# tionpipetionpipetionpipenodenode PPPPP −−− ∆−∆−∆−=⇒

barPnode 008.6416.1576.083# =−−=barPnode 246.6678.0500.0576.086# =−−−=barPnode 172.7248.0500.0576.085# =+−−=

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics



Introduction of soft ware

Pipe Net Standard Module

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics

Introduction of software



What is pipe net ?

The PIPENET suite of programs has been designed to enable the accurate simulation of fluid through a network of pipes and other components.

The full suite of programs consists of the following modules:

1-Standard Module: For general flow analysis of the single phase flow of liquids and gases.

2-Spray / Sprinkler Module: Specifically for the design of fire protection systems (deluge, ring main or sprinkler) in accordance with NFPA rules .

3-Transient Module: For the analysis of transient flow in all types of network employing a liquid. It has many applications including predicting pressure surges, calculating hydraulic transient forces and modeling control systems.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Applications

-Powerful tool in the design (sizing & pressure drop calculation) of piping systems contain single phase steady flow of liquids and gases.

-It is also a flexible tool for simulation of ducts, pumps, fans, filters, control valves, non-return valves, orifice plates, nozzles and fixed pressure drops in the piping systems.

-It can be used as an aid in designing a new network of pipes with appropriate pipe sizes and ensuring that the system specification requirements are met. It can also be used to investigate the consequences of blocked or broken pipes in the network.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




What is the advantage of this soft ware:

- A large number of inputs and outputs.

- Units - Metric, SI, British, US or User defined.

- Networks comprising any arrangement of branches, grids and loops.

- Open and closed loop systems.

- Incompressible and compressible fluids.

- Fluids at a fixed or variable temperature.

- Built-in fittings and pipe schedules and user defined fittings, pipe schedules and fluids.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics




Applications

- Ring mains for water supply.

- Coolant systems and Steam networks.

- Crude oil and Fuel oil supply lines.

- Air ducting systems.

- Water injection and Gas distribution systems.

Example 1



PIPING



Recommendations

Pressure drop

Velocity

Sizing Criteria



Labeling Diagram

Piping Network

Topics


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Hydraulic Calculation Lecture-Piping I

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