1. Design of a Gas Pipeline & Main Equipment , System in Gas Pipeline by
PETROFED
(6th Programme on Oil & Gas transportation through Pipeline)
IIPM GURGAON
8th- -10th July , 2009
Intricacies of
Design of a Gas Pipeline
&
Main Equipment , System in Gas Pipeline by
Rahul Gautam
Chief Manager (Pipeline)
Project Development
GAIL(INDIA) LTD

2. Contents Typical Pipeline System Typical Input Parameter for designing
Design Basis
Modeling & Simulation
Optimization
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD

3. Typical Pipeline System
Pipeline Types
Gas Source
Gas Gathering System
Gas
Treatment
Gas
Transmission
Gas
Distribution
Typical Gas Transmission & Distribution DT SV IP RT RT
DT: Dispatch Terminal
SV: Sectionalizing Valve
IP : Intermediate Pigging Station
RT : Receiving Terminal
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
Contd.…

4. Typical Schematic for Pipeline System
Typical Pipeline System
x- ings
RAIL/ROAD/RIVER
GAS FIELD
RECEIVING
TERMINAL / DELIVERY TERMINAL CS
GGS & GT
CTP IP SV
SV: Sectionalizing Valve
IP : Intermediate Pigging Station
CS: Compressor Station
RT : Receiving Terminal
GGS : Gas Gathering System
GT: Gas Treatment
GAS
RECEIVING
STATION
Typical Schematic for Pipeline System

5. Typical Pipeline System
A typical gas pipeline system comprise of the following
Gas Receiving Station
- Place where pipeline receives the gas.
Sectionalizing Valve Station
- To carry out routine maintenance or emergency
maintenance of pipeline venting of gas is to be restricted.
Intermediate Pigging Station
- To ensure continuous gas flow through pipeline, regular
and periodical cleaning of pipeline is required.
- The pigging is carried out various kind of Pig e.g. Scrapper Pig,
Gauzing Pig, Foam Pig etc.
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD

6. Typical Pipeline System
A V
T G
P G
TYPICAL SV STATION
Utility Connection – 2”
By pass Line
MAINLINE
MANIFOLD FOR PG /TG

7. Typical Pipeline System

8. Typical Pipeline System
Compression System
- To economize the flow through pipeline
- Located enroute of the pipeline to boost the gas pressure
- Reciprocating compressor verse Centrifugal compressor
- Reciprocating compressor : up to gas volume of SCM/Hr
higher compression ration ( up to 10)
- Centrifugal compressor : higher volume flow
Compression ratio 1.5 to 2.0
Compressor installation like a process
plant requiring all kind of utilities
(Power, Water, Air, Fuel , Fire Fighting
and Control Room System)
Receiving Terminal
- For supplying gas to various customers : designed to handle the
required flow for single
and multiple users.
- The terminal contain filters, pressure regulator, heater, metering
device, online gas chromatograph, flow computer and odorizing unit
(if required) 8
Contd.…
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD 8

9. TRANSPORTATION OF GAS WITH COMPRESSOR STATIONS (TYPICAL)
Typical Pipeline System CS
Off take of Gas CS CS
Gas Supply Pressure CS CS
Delivery of gas
TRANSPORTATION OF GAS WITH COMPRESSOR STATIONS (TYPICAL) 9
Contd.…
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD 9

10. Typical Pipeline System
Scrubber
Filters
P R Unit
Metering Unit
Custody T/P
PCV-1
SDV-1
Meter-1
Flow computer-1
15 Mts
Gas Chromatograph
SDV-2
PCV-2
Meter-2
Flow computer-2
By-Pass
40 Meter
Schematic (Typical ) for Receiving Terminal at Customer site
Not to Scale

11. Typical Input Parameters
Type of Natural Gas
- Associated Gas
- Non Associated Gas / Free Gas
- Dry Natural Gas
- Wet Natural Gas
- Sour Natural Gas
Gas Composition
Gas Supply Pressure and Temperature
Gas Volume ( To be Transported) and off-Take of gas enroute
pipeline ( if any)
Route / Terrain
Delivery Point
Gas volume at delivery point
Required Pressure and Temperature at Delivery Point 11
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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12. Design Basis Pipeline System Starting Point
- Supply Gas Pressure (Kg/Cm2g)
- Supply Gas Temperature (deg. C)
- Gas Volume
- Gas Quality and Gas Composition
Route /Terrain
- Class location
- x-ings ( NH/SH/RAIL/ROAD/RIVER/MAJOR RIVER)
Delivery Point
- Delivery Gas Pressure (Kg/Cm2g)
- Delivery Gas Temperature (deg. C)
- Gas Volume
- Gas Quality and Gas Composition 12
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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13. Design Basis Linepipe - Design Pressure - Wall Thickness
- Roughness with internal coating and without internal coating
- Gas Composition
- Soil temperature
- Elevation
- Efficiency
- Flow
- Configuration
-Velocity in pipe
Metering
- Supply Pressure and temperature
- Flow
- Gas Quality and Gas Composition
- Type of meter (Orifice / Turbine Meter / USM)
- Configuration
- Pressure Loss
- Accuracy
- Rangeability 13
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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14. Design Basis Compressor Station - Gas arrival pressure and Temperature
- Compressor Ratio
- Discharge Pressure and Temperature of Gas
- Flow
- Gas Quality and Gas Composition
- Compression efficiency
- Compression spacing
- Compressibility
- Configuration
- Compression Power 14
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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15. Modeling and Simulation
Pipeline modeling constitutes a Graphical Representation of the pipeline system involving receiving stations Sectionalizing Valve Station, Intermediate Pigging Station, Compressor / Pump Station and Receiving Terminal.
- Pipeline design (optimal Line pipe size, compressor requirement, loop line and
other equipments location including SCADA & Telemetry System)
- Pipeline performance (Throughput optimization)
- Tracking gas composition
- Minimize fuel consumption
- Pipeline systems operation
- Create Emergency Plan
- Leak Detection Module
- Alarms Generation 15
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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16. TYPICAL SCHEMATIC FOR MODELLING PIPELINE SYSTEM
End Point
Dedicated Pipeline
Spurline
770 KM
Trunk Line
TRUNK LINE
CUSTOMER LOCATION
TAP-OFF POINTS
CGD
SPURLINES
40 KM
Compressor
Starting Point
TYPICAL SCHEMATIC FOR MODELLING PIPELINE SYSTEM

17. Modeling and Simulation
- Compressibility
- Improving delivery by making use of line pack which being function
of Pipeline pressure.
Simulator model basically works with various equation of state to compute the desire result by employing advance numerical solutions technique. Most of the simulator models have been developed by various companies who have been involved in pipeline design or information technology solution including monitoring & Control of Physical parameters. 17
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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18. Modeling and Simulation
Hydraulics /Simulation
Flow Equation
- General flow equation
- Cole-Brook white equation
- Modified Cole-Brook White equation
- AGA equation
- Weymouth equation
- Panhandle A Equation
- Panhandle B equation
The General Flow equation , also called the fundamental flow equation, for the steady state isothermal gas flow in a gas pipeline is the basic equation for relating the pressure drop with flow rate
Qb = 1.15 x 10^-3 * (Tb/ Pb) ( P1^2-P2^2 / G Tf L Z f ) ^0.5 * D^2.5
Where
Qb- gas flow rate in m3/day, Tb- base temperature , K (273+deg.C), P1- U/S pressure in kpa
f- friction factor, P2 –down stream pressure , kpa, G- gas gravity (air=1.00)
Pb- base pressure in kpa , Tf –average gas flow temperature, K (273+deg.C)
Z-gas compressibility factor at the flowing temperature , D-pipe inside diameter 18
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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19. Modeling and Simulation
Velocity in Pipes
- Represents the speed at which gas molecules move from one point to another
- Due to compressibility , the gas velocity depends upon the pressure
- Vary in pipeline, even the pipe diameter is constant
- Highest velocity at the down stream of pipeline where the pressure is the least
- Least velocity at the up stream where pressure is higher
The gas velocity at any point in a gas pipeline is given by
u=14.74 (Qb/D^2) (Pb/Tb) (ZT/P)
Where
u – gas velocity( m/s) , Qb - gas flow rate, measured at standard condition ( m^3/day), D- pipe inside diameter ( mm ), Pb- Base pressure (Kpa), Tb- average gas flowing temperature (deg. K), Z- compressibility factor at the flowing temperature, dimensionless
Erosional Velocity
Gas velocity is directly related the flow rate. As the flow rate increases, so the gas
velocity increases.
As the velocity increases, vibration and noise are evident
Higher velocities will cause erosion of the pipe interior over a long period of time.
u (max) =100 / (d) ^1/2 u (max) – ft/ s, d = gas density at flowing temperature , lb/ ft ^3 19
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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20. Modeling and Simulation
Reynolds Number
-Reynolds number is used to characterize the type of flow in a pipe, such as laminar, turbulent
or critical flow
- It is also used to calculate the friction factor in pipe flow
- It depends upon property of gas, pipe diameter etc.
Re = u D d / n
Where
Re- dimensionless, u-average velocity (m/s), D- inside diameter (mm),
d- gas density(kg/m^3), n-gas viscosity (kg /m-s)
The Reynolds number is
Re = (G Qb/n D) (Pb/Tb)
G – specific gravity of gas (air=1.0), Qb - gas flow rate, measured at standard condition ( m^3/day), D- pipe inside diameter ( mm ), Pb- Base pressure (Kpa), Tb- average gas flowing temperature (deg. K), n-viscosity of gas , poise
Laminar flow – The Re. No. is less than and equal to 2000
Turbulent flow - The Re. No. is greater 4000
Critical flow The Re. No. is undefined and in between 2000 and 4000 20
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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21. Modeling and Simulation
Friction factor
- Friction factor is dimensionless parameter and depends upon Reynolds Number of flow.
- Darcy and Fanning two friction factor are generally used, But Darcy friction factor is more
common.
Friction factor (ff ) = Darcy Friction factor (fd) /4
Moody diagram is graphic plot of the variation of the friction factor with the Reynolds number for various values of relative pipe roughness. It is a dimensionless parameter obtained by dividing the absolute (or internal pipe roughness )by the pipe diameter.
Where
Re- dimensionless, u-average velocity (m/s), D- inside diameter (mm),
d- gas density(kg/m^3), n-gas viscosity (kg /m-s)
Relative roughness : e / D
e = absolute or internal roughness of the pipe (mm)
D= pipe inside diameter (mm) 21
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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22. Pipe internal Roughness
Modeling and Simulation
Moody diagram
Laminar
Critical
Turbulent
Pipe internal Roughness
Pipe Material Roughness (mm)
Riveted Steel to 9.0
Commercial/
Welded Steel
Cast Iron
Galvanized Iron
Asphalted Cast Iron
Wrought Iron
PVC, drawn tubing, glass
Concrete
Friction factor
Roughness
Reynolds Number 22
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD 22

23. Modeling and Simulation
Other Parameters
- The effect of intermediate delivery volumes and gas injection rates along a gas pipeline
- The effect of contract delivery pressure, and regulating the pressure through control valve
- Thermal effects due to heat transfer between the gas and the surrounding soil in the buried
pipe due to
Soil temperature
Thermal Conductivities
Joule Thompson Effect 23
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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24. Pipeline Configuration
Optimization
- Without Intermediate Compressor
- With Intermediate Compressor
- With Intermediate Compressor and Loop Lining
Pipeline Configuration 24
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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25. Optimization Pipeline Configuration 100MMSCMD 50MMSCMD 50 MMSCMD
- The total pressure required for transporting gas in a pipeline under various configuration,
such as series and parallel
100MMSCMD MMSCMD MMSCMD
Series
20 MMSCMD MMSCMD
50MMSCMD
Parallel
100MMSCMD
50 MMSCMD - 25
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD 25

26. Optimization Metering System Rangeability 3:1 10:1 50:1
Orifice Turbine Ultrasonic
Standard AGA Rep AGA Rep AGA Rep. 9
Accuracy < 1% +/_0.5 % < +/- 0.5%
Rangeability : : :1
Pressure Loss Negligible
(Kg/Cm2g)
Cycle Flow Generally Appreciable Not Affected
Variation over reg.
Liquid in gas Corrosion & Corrosion & Corrosion possible
erosion damage to moving
parts 26
Rahul Gautam Chief Manger (Pipeline) Project Development GAIL(INDIA) LTD
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27. Thank You 27 27