1. City Gas Distribution: A Network Analysis

2. Overall view

3. City gas distribution in India
Oil India ltd. was first to start distribution gas in Assam in 1960’s.
As a pilot project first city gas distribution was taken up with help of ONGC at Vadodara city in 1972.
GGCL was the first commercial city gas distributon company in India.
MGL & IGL starts city gas distribution in domestic, commercial & transport sector in Mumbai(1995) & Delhi(1998) respectively.

4. Natural Gas Why Natural gas? Advantages: Safe and clean fuel.
Excellent combustion properties.
Cheap and easily available.
Future fuel.

5. Demand of Natural Gas
Domestic gas demand in India is of order of 179MMSCMD in

6. Consumption of Natural gas

7. Feasibility

8. System design
Selection of route.
Optimum route.
System basic concept

9. Selection of route
Maximum reach of potential demand centers with minimum length.
Use of existing defined pipeline corridors by respective authorities.
Minimum disturbance to agricultural land.
Safety of people and property.
Avoidance of rocky terrain.
Flexibility of future expansion.

10. Optimum route Shortest length of pipeline grid.
Least topographical variation and minimum obstacles.
Minimum cost of system layout.
Density of traffic should be low.
Minimum no. of turning points.

11. System basic concept Pressure levels Medium pressure (26 barg)
Low pressure
(4 barg)
High pressure
(49 barg)

12. Network Steel mains (network) High pressure mains
Medium pressure mains
Above ground mains
Polyethylene
Cover clearance protection
Sectionalizing

13. Construction activities
Opening of Right of Way
Clearing & grading
Welding & radiography
Joint coating
Crossings
Hydrostatic testing

14. Sectors for city gas distribution
CNG – Transport sector
PNG – Domestic sector
PNG – Commercial sector
PNG – Industrial sector

15. Various station involved in network
City gate station (CGS)
Industrial pressure reducing station (IPRS)
District regulating station (DRS)

17. Layout of service connection
Mild density polyethylene (MDPE) as gas pipe.
Domestic connection layout

18. MDPE as gas pipe Balance rigidity & toughness Excellent ductility
Very low permeation to gas
Resistance to rapid crack
Extremely smoother interior surface
Easy to transport, handle & lay
Longer life

20. Domestic connection layout

21. Polyethylene Pipe Joining
An integral part of any pipe system is the method
used to join the system components.
Thermal heat fusion method
1. Butt fusion
2. Saddle/conventional fusion
3. Socket fusion
Electro fusion

22. Thermal Heat Fusion
Principle of heat fusion is to heat two surfaces to a designated temperature and then fuse them together by application of sufficient force.
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23. Butt fusion Most widely used method of joining.
It produces permanent, economical and flow efficient connection.

24. Saddle/conventional fusion
This is used to join a saddle to a pipe.
The external surface of both the pipe is heated and the matching surface are fitted with the help of concave and convex shaped heating tools.

25. Socket Fusion
In this technique, both the internal as well as the external surface is heated.

26. Electro Fusion

27. Maintenance Pipeline failure investigation
Periodic surveillance of pipelines
Cathodic protection.

28. Future advancement
Details of Non returning valve & metering device used in door to door supply of PNG.
Fabrication of NRV
Electric log model of city gas distribution
Details of horizontal directional drilling & auger boring.
Flow rate calculation of particular sections of a pipeline.