CITY GAS DISTRIBUTION
GSPC GAS
The Pathway
GSPC Gas Company Ltd., a group company of the Gujarat State Petroleum Corporation has been
established to complete the presence of GSPC in the Energy Value Chain. GSPC Gas always
works towards a principal aim to supply natural gas to retail customers, i.e. Domestic,
Commercial/Non-Commercial, Industrial and CNG. GSPC Gas is playing a vital role to cater to
the natural gas demand up to the last mile of the retail network. GSPC Gas is envisioned to be
complementary to Gujarat State Petronet Ltd. (GSPL), which is evident from the presence of
GSPC Gas retail network starting at every point and location that the GSPL network ends.
Core Philosophy
The GSPC Group's foray into Gas Distribution in a big way bears testimony to the core
philosophy of being 'A Complete Energy Company'.
Main Segments (Status on 31st May 2014)
GSPC Gas is supplying natural gas to more than 4, 96,138 domestic households, 1,918
commercial and non-commercial segments and 1,897 industrial customers. GSPC Gas also
supplies natural gas in the form of Compressed Natural Gas (CNG) through 159 CNG
stations across the state that caters to more than 89,000 vehicles per day.
PNG Domestic
PNG Industrial
PNG Commercial
Figure 1 - Main Sectors where Natural Gas is provided by GSPC Gas
1
City Gas Distribution by Sarthak Kishore| GSPC GAS
CNG
Chapter 1 – Natural Gas and its Applications
Naturally gas is composed primarily of Methane with minor quantities of Ethane, Propane,
Carbon Dioxide, Nitrogen and Traces of Higher Hydrocarbon and Oxygen. It is a vital
component of the world's supply of energy. It is one of the cleanest, safest, and most useful of all
energy sources.
It is a Non- Poisonous, Non- Toxic, Colorless, tasteless combustible source of Energy. It has no
odor of its own; however, for City Gas Distribution Ethyl Mercaptan is added for distinct color
so that layman can identify the leak if any nearby and report to the authorities for necessary
corrective option.
Table 1 - Composition of Natural Gas
Component
Chemical Formulae
Percentage
Methane
Ethane
Propane
Butane
Carbon Dioxide
Oxygen
Nitrogen
Hydrogen Sulphide
Rare Gases
CH4
C2H6
C3H8
C4H10
C02
02
N2
H2S
He, Ne, Ar, Xe
70%-90%
0%-20%
0%-8%
0%-0.2%
0%-5%
0%-5%
Traces
Table 2 - Properties of Natural Gas
Specific Gravity (Air 1.0)
0.56% to 0.67%
Boiling Point
-161°C
Melting Point
-182°C
Flash Point
-161°C
Auto Ignition Temperature
560°C
Flammable Limit
5% to 15% by volume in air
Critical Pressure
45.99 Bar
Critical Temperature
-82.59°C
Natural Gas Applications
I.
Domestic Usage: Most commonly known use of Natural Gas. It can be used for
cooking, water warming, heating and air conditioning. Domestic appliances are
increasingly improved in order to use natural gas more economically and safely.
Operating cost of natural gas equipment is generally lower than those of other energy
sources.
II.
Industrial Usage: It is used to treat waste material, for incineration, drying,
dehumidification, heating and cooling, and cogeneration. It is used as an input to
manufacture pulp and paper, metals, chemicals, clay, glass and to process certain foods.
III.
Commercial Purpose: Main commercial centers which use natural gas are Hotels,
healthcare facilities and office buildings for cooking, cooling and heating purposes.
IV.
Natural Gas Vehicles (NGVs): It can be used as a motor vehicle fuel – as CNG
(Compressed Natural Gas) and as LPG (Liquefied Natural Gas). Natural gas vehicles
fleet accounts for about one and a half million vehicles worldwide. Concerns about air
quality in most parts of the world are increasing the interest in using natural gas as a fuel
for vehicles. Cars using natural gas are estimated to emit 20% less greenhouse gases than
gasoline or diesel cars. In many countries NGVs are introduced to replace buses, taxis
and other public vehicle fleets. Natural gas in vehicles is inexpensive and convenient.
Figure 2 - Natural Gas Consumption In India (Sector wise), 2011
Chapter 2 - what is CNG and PNG?
2.1. CNG (Compressed Natural Gas)

CNG (compressed natural gas) is natural gas mainly containing methane which is
compressed up to 250 bars and used as vehicular fuel in vehicles running on CNG kits.

It has a Research Octane Number in excess of 120. The excellent knock resisting
property of CNG allows for use of a higher compression ratio resulting in an increased
power output and greater fuel economy when compared to petrol.

CNG can be used in engines with a compression ratio as high as 12:1 compared to normal
gasoline (7.5:1 to 10:1). At this high compression ratio, natural gas-fuelled engines have
higher thermal efficiencies than those fuelled by gasoline. The fuel efficiency of CNG
driven engines is about 10-20% better than diesel engines.
The following are the benefits of using CNG:
1. Green Fuel
Commonly referred to as the green fuel because of its lead and Sulphur free character, CNG
reduces harmful emissions. Being non-corrosive, it enhances the longevity of spark plugs. Due to
the absence of any lead or benzene content in CNG, the lead fouling of spark plugs and lead or
benzene pollution are eliminated.
2. Increased life of Oil
CNG does not contaminate and dilute the crankcase oil.
3. Mixes evenly in Air
Being a gaseous fuel CNG mixes in the air easily and evenly.
4. Safety
CNG is less likely to auto-ignite on hot surfaces, since it has a high auto-ignition temperature
(540°C) and a narrow range (5%-15%) of inflammability. It means that if CNG concentration in
the air is below 5% or above 15%, it will not burn.
5. Low Operational Cost
At the prevailing price of fuel in Gujarat, operational cost of CNG vehicles is 68% lower than
petrol and 36% lower than diesel.
2.2. Piped Natural Gas (PNG)
Natural gas which is maintained at low pressure less than 4 bar and carried by poly ethylene
pipeline mainly used for cooking in houses and various industrial purposes.
The ratio of carbon to hydrogen is least in methane and hence it burns almost completely making
it the cleanest fuel. It is procured from the oil / gas wells and transported through a network of
pipelines across the country.
The following are the benefits of using PNG:
1. Uninterrupted Supply
PNG offers the convenience of ensuring continuous and adequate supply of NG through pipeline,
without any storage of gas in cylinders.
2. Unmatched Convenience
The domestic consumers have to take upon themselves the tiresome task of booking an LPG
cylinder; refill time and again start the wait for the deliveryman to deliver the cylinder. Switching
over to PNG renders this entire exercise unnecessary. PNG also eliminates the tedious routine of
checking LPG refill cylinder for any suspected leakage, or it being underweight, at the time of
delivery. Precious space, occupied by LPG cylinders is also saved.
3. Safety
The combustible mixture of natural gas and air does not ignite if the mixture is leaner than 5%
and richer than 15% of the air-fuel ratio required for ignition. This narrow inflammability range
makes NG one of the safest fuels in the world.
Natural gas is lighter than air. Therefore, in case of a leakage, it just rises and disperses into thin
air given adequate ventilation. But LPG being heavier will settle at the bottom near the floor
surface.
A large quantity of LPG is stored in liquefied form in a cylinder. With PNG, it is safer since PNG
installation inside your premises contains only a limited quantity of natural gas at low pressure
i.e. 21 millibar.
On leakage, LPG expands 250 times, which is not the case with PNG. Supply in PNG can be
switched off through appliance valve and isolation valve, which fully cuts off the gas supply.
4. Billing
The user is charged only for the amount of PNG used, and no pilferage is possible with PNG as
the billing is done according to the meter. A unique feature is that the user gets to pay only after
consumption of gas. The domestic consumer pays the PNG bill only once in two months.
Moreover, there are no minimum consumption charges i.e., if there hasn’t been any consumption,
there shall not be any bill.
The user pays the gas consumption charges based on the exact consumption reading provided by
the meter installed at his premises. The bill is delivered at the user’s doorstep.
5. Customer Support
Round-the-clock customer support is assured through 24 hours toll free number backed by
control rooms, which are manned by engineers and trained technicians. Thus complaints, if any,
are promptly redressed.
6. A Versatile Fuel
Natural gas is being used predominantly as a versatile fuel in many major cities catering to
domestic and commercial applications, as a cooking fuel, for water heating, space heating, air
conditioning, etc.
7. Environment Friendly
Natural gas is one of the cleanest burning fossil fuels, and helps improve the quality of air,
especially when used in place of other more polluting energy sources. Its combustion results in
virtually no atmospheric emissions of Sulphur dioxide (SO 2), and far lower emissions of carbon
monoxide (CO), reactive hydrocarbons and carbon dioxide, than combustion of other fossil fuels.
8. No Daily Liasioning
The consumer is spared the task of liasioning with oil companies and co-coordinating with them
for ensuring the daily supply of fuel, because PNG is supplied directly through pipes. The daily
bills, settlements and reconciliation are also avoided as the consumer is billed once a month, and
that too as per the meter reading.
Chapter 3 – Overview of CGD Business
A City gas distribution means a distribution system in which CNG & PNG sold to various
segments by interconnecting gas pipeline & related equipments.
Currently the CGD segment constitutes 10 percent of the total gas consumption in India. It is
worth noting that this has been achieved in the past five years itself. It is expected to reach a
share of 20 percent by FY20. The supply of natural gas for CGD is around 13 mmscmd in FY11
against the demand of 15.83 mmscmd in the country. Increasing demand from commercial and
small industrial customers within the city limits, in addition to the automotive and residential
demand, are the key drivers of growth in this segment. Much of the demand in future will
continue to be as a result of customers finding natural gas to be more competitive than other
fuels coupled with ease of handling and lower pollution.
On the supply side expectation of large volumes of gas being made available within the next few
years, though both new domestic finds and imports, has created greater compulsions for
developing the CGD market. With an estimated demand of 100 mmscmd by FY 20, CGD market
is expected to grow by leaps and bounds.
3.1. CGD Players in India
Table 3
S.
No.
Name of the CGD
Network
Area Covered
1
2
3
4
5
6
Sonipat CGD Network
Meerut CGD Network
Kakinada CGD Network
Dewas CGD Network
Kota CGD Network
Mathura CGD Network
Sonipat
Meerut
Kakinada
Dewas
Kota
Mathura
7
8
9
10
11
12
13
Chandigarh CGD Network
Allahabad CGD Network
Jalandhar CGD Network
Jhansi CGD Network
Bhavnagar CGD Network
Jamnagar CGD Network
Firozabad Geographical Area
14
15
Agra CGD Network
Hyderabad CGD Network
Chandigarh
Allahabad
Jalandhar
Jhansi
Bhavnagar
Jamnagar
Firozabad
Geographical
Area (U.P.)
Agra
Hyderabad
Entity Authorized
Gail Gas Limited
Gail Gas Limited
Bhagyanagar Gas Limited
Gail Gas Limited
Gail Gas Limited
JV of M/s DSM Infratech Pvt. Ltd. &
M/s Saumya Mining Pvt. Ltd.
M/s IOCL-AGL
M/s IOCL-AGL
M/s Jay Madhok Energy Pvt. Ltd.
M/s Central UP Gas Ltd.
M/s Gujarat Gas Company Ltd.
GSPC Gas Company Limited
GAIL Gas Ltd.
Green Gas Ltd.
Bhagyanagar Gas Ltd.
16
Indore CGD Network
17
18
Gwalior CGD Network
Gandhinagar, Mehsana,
Sabarkantha CGD Network
19
20
21
22
Indore including Avantika Gas Ltd.
Ujjain
Gwalior
Gandhinagar,
Mehsana,
Sabarkantha
Pune City including Pimpri, Pune City
Chichwad CGD Network
INCLUDING
Pimpri,
Chichwad
Kanpur CGD Network
Kanpur GA
Bareilly CGD Network
Bareilly GA
Delhi CGD Network
National Capital
Territory of Delhi
Avantika Gas Ltd.
Sabarmati Gas Ltd.
Maharashtra Natural Gas Ltd.
Central U.P. Gas Ltd.
Central U.P. Gas Ltd.
Indraprastha Gas Ltd.
23
Mumbai CGD Network
Mumbai and
Mahanagar Gas Ltd.
Greater Mumbai
24
25
Vijaywada CGD Network
Mumbai CGD Network
Vijaywada GA
Thane City and
Adjoining areas
Bhagyanagar Gas Ltd.
Mahanagar Gas Ltd.
26
Rajkot
GSPC Gas Company Limited
27
Surendranagar
28
Navsari
29
Nadiad
30
Khurja
31
Moradabad
31
Surat-Bharuch-Ankleshwar
Rajkot
Geographical
Area
Surendranagar
Geographical
Area
Navsari
Geographical
Area
Nadiad
Geographical
Area
Khurja
Geographical
Area
Moradabad
Geographical
Area
Surat-BharuchAnkleshwar
Geographical
GSPC Gas Company Limited
GSPC Gas Company Limited
GSPC Gas Company Limited
Adani Gas Limited
Siti Energy Limited
Gujarat Gas Company Limited
Area
Chapter 4 - Applicable Codes and Practices
Table 4 - EUROPEAN STANDARD (EU)
S. NO.
STANDARD NO.
DESCRIPTION
1.
EN 12186
2.
EN 12279
3.
EN 1776
Gas supply systems – Gas pressure regulating
stations for transmission and distribution functional
requirements
Gas pressure regulating – installations on service
lines
Gas supply systems – Natural gas measuring stations
– Functional Requirements
4.
EN 1594
Gas supply systems – Pipeline for maximum
operating pressure over 16 bar-Functional
Requirements
Table 5 - AMERICAN SOCIETY OF MECHANICAL ENGINEERS
(ASME)
S. NO.
STANDARD NO.
DESCRIPTION
1.
ASME B16.11
2.
ASME B31.3
Forged steel fittings, socket-welding and
threaded
Process piping
3.
ASME B31.8
4.
ASME B16.5
5.
ASME B16.9
6.
ASME – Boiler and Pressure
Vessel Code
Gas transmission and distribution piping
systems
Pipeline flanges and flanged fittings
Factory – Made wrought steel butt welding
fittings
Section 9- Qualification standard for welding
and brazing procedures, welders, brazers, and
welding and razing operations
7.
ASME – Boiler and Pressure
Vessel Code – 2
Part C – Specifications for welding rods,
electrodes, and filler metals
8.
ASME – Boiler and Pressure
Vessel Code
Section 5, Non-destructive examination
9.
ASME – Boiler and Pressure
Vessel Code
Section 2 Materials Part A-ferrous Material
Specifications
Table 6 - OIL INDUSTRY SAFETY DIRECTORATE (OISD
STANDARDS)
S. NO.
STANDARD NO.
DESCRIPTION
1.
OISD-226
2.
OISD-GDN-115
3.
4.
FIRE PROTECTION
MANUAL – TAC
OISD – STANDARD – 141
5.
OISD STANDARD - 118
Natural gas transmission pipelines and city
gas distribution network
Guidelines for firefighting, equipment and
appliances in Petroleum Industry
Fire Engines, Trailer Pumps and Hydrant
Systems
Design and construction requirement for cross
country hydrocarbon pipelines
Layout for oil and gas Installations
Table 7 - AMERICAN GAS ASSOCIATION (AGA)
S. NO.
STANDARD NO.
DESCRIPTION
1.
AGA
Purging Principles and Practices
2.
IGE/T/1
3.
AGA: REPORT NO. 7
Steel pipelines for high pressure gas
transmission
Measurement of gas by turbine meters
4.
AGA: REPORT NO. 8
5.
AGA: REPORT NO. 3
Orifice metering of natural gas and other
related HC fluids
Compressibility factors of natural gas and
other related HC gases
Table 8 - AMERICAN PETROLEUM INSTITUTE (API)
S. NO.
STANDARD NO.
DESCRIPTION
1.
API STANDARD 1104
Welding of pipelines and related material
2.
API SPECIFICATION 5L
Specification for line pipe
3.
API SPEC. 6D
Specification for Pipeline Valves
4.
API STANDARD 1102
Specification for Steel pipeline crossing and
highways
Table 9 - BS/DIN/ISO AND OTHER STANDARDS
S. NO.
STANDARD NO.
1.
ISO-15590-1
2.
BS 6755:PART 2
3.
DIN 30672, PART 1
4.
DIN 30670
DESCRIPTION
International standard for Petroleum and
natural gas industries – Induction bends,
fittings and flanges for pipeline transportation
systems
Testing of Valves
Coatings of corrosion protection tapes and
heat-shrinking products for pipelines for
operational temperatures up to 50°C
Polyethylene Coatings for Steel Pipelines and
Fittings
Table 10 - T4S – TECHNICAL STANDARDS AND SPECIFICATIONS
INCLUDING SAFETY STANDARDS FOR CITY OR LOCAL NATURAL GAS
DISTRIBUTION NETWORK
S. NO.
STANDARD
DESCRIPTION
1.
SCHEDULE 1A
Materials and Equipment
2.
SCHEDULE 1B
Welding
3.
SCHEDULE 1C
4.
SCHEDULE 1D
Piping Systems Components and Fabrication
Details
Design, Installation and Testing
5.
SCHEDULE 1E
Operating and Maintenances Procedures
6.
SCHEDULE 1F
Corrosion Control
7.
SCHEDULE 1G
Miscellaneous
CITY GAS DISTRIBUTION
Chapter 5 - City Gas Distribution Network
-
The selection of design for CGD Network is based on the gas properties, required flow
rates, operating pressures and the environment.
-
A typical CGD Network shall comprise of one or more or all of the following:
1.) City Gas Station (CGS)
2.) Pipeline Network – Steel Pipeline, Polyethylene Pipelines, GI/Cu Pipes
3.) Regulating Stations – District Regulating Stations (DRS), Service Regulators, Domestic/
Commercial/ Industrial Regulators
4.) Metering Stations/ Metering & Regulating Stations (MRS)
5.) CNG Stations
Fi
gure 3 – Basic System Flow Diagram (Schematic)
13
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.1. City Gas Station (CGS)
It is established at a tap-off point of high pressure transmission pipeline; from where we get gas
inside the city via pipelines. The gas delivered at this point is at higher pressure i.e. greater than
40 bar. Once gas enters to CGS unit its pressure is reduced to in between 25-30 bar.
Figure 4 – City Gas Station (CGS)
The main Components of City Gas Station and their function is as follows –
5.1.1. Filtration Skid: Dust particle and liquid coming with the gas stream are separated by
high efficient filters in KOD. Gas is maintaining same pressure from the inlet to the filtration
skid. After the filtration two streams are dividing from the main line using a header. Line which
is in function is known as active line where another one is called passive line.
Figure 5 – Filtration Skid at CGS
14
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.1.2. Pressure Reduction Unit: A pressure reduction valve is installed for the reduction
of the gas stream pressure from 40-45 bars to 25-30 bars. Creep relief valve and Slam Shut off
valve is being installed in this skid for the safety purpose.
Figure 6 – Pressure Reduction Unit
5.1.3. Metering Skid: Metering skid is installed for the gas flow measurement. Orifice meter
is used in this metering skid; because of the large pressure drop requirement. The various
parameters such as temperature in the various sections of the line pressure at the inlet & outlet
joints, flow inlet & outlet are monitor by the SCADA systems in the control room.
Figure 7 – Custody Transfer Meter at CGS
15
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.1.4. Odorization Unit: An Odorization unit is installed for addition of ethyl Mercaptan in
the gas stream. The dozing unit of the ethyl Mercaptan should be of 9 mg/m3. This unit consists
of mainly two cylinders of capacity of 160 kg, pneumatic panel, level indicator and a filter. This
unit is directly connected to the main line after the metering skid.
Figure 8 – Odorization Unit
5.2. Steel Pipeline – It is the Primary Network in the form of Transmission Pipeline (Up
to CGS) and Distribution Pipeline (CGS Downstream, Ring).
Figure 9 – Steel Pipeline Site
16
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.2.1. Design / Hydraulics / Simulation

Simulation for Network Hydraulics is done in the SYNERGEE software.

This is basically required to derive diameter of pipeline in such a way that required
pressure at all locations can be achieved and future load projections can be ascertained.

Formulae used for hydraulics: Colebrook White / Fundamental pipe equation with flow
dependent friction factor.

Efficiency factor: 0.85 – 1

Velocity: Max. Allowable velocity of the gas in the steel pipeline Section of CGD
network shall be 30 m/s.

STP: Standard Pressure: 1.01325 Bar, Standard Temperature: 15.5°C

Design Life: Steel Pipeline: 30 Years, PE Pipeline: 50 Years
Table 11 - Location Class Considerations
Location Class
Description
Design Factor
Class 1
10 or fewer buildings in 1mile section
0.72
Class 2
10 – 46 buildings
0.60
Class 3
46 or more buildings
0.50
Class 4
areas where multistoried buildings and heavy
underground utilities
0.40
Wall Thickness Calculation for Steel Pipeline
P = 2St FET/D
Where,
P = Design Pressure
S = Specified minimum yield strength
D = Nominal OD of pipe
t = Nominal wall thickness
F = Design Factor
E = Longitudinal joint factor
T = Temperature de-rating factor
17
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.2.2. Line Pipe – Selection/Specification and Coating
5.2.2.1. Type:
I.
II.
III.
IV.
ERW (Electric Resistance Welded)
HSAW (Helical Submerged Arc Welded Pipe)
LSAW (Longitudinal Submerged Arc Welded Pipe)
Seamless Pipes
5.2.2.2. Coating – To protect them from corrosion.
I.
II.
III.
Coal Tar Enamel Coating (BS 4164, AWWA C203)
3 Layer PE/ PP Coating (DIN 30670)
Fusion Bonded Epoxy Coating (CSA Z245.20)
5.2.3. Fittings, Valves and Welding
5.2.3.1. Fittings: ASTM A234 and ANSI B 16.5 & 16.11
1.
2.
3.
4.
Elbows & Bends
Flow Tees & Fasteners
Insulating Joints
Flanges & Gaskets
5.2.3.2. Valves: API 6D
1. Sectional Valves and Tap Off Valves (future provisions)
2. Ball Valve, Gate Valve, Plug Valve, Check Valve, SRV, NRV
5.2.3.3. Welding:
1.) Fillet weld: A weld of approximately triangular cross section joining two surfaces
approximately at right angles to each other in a lap joint, tee joint, or corner joint.
2.) Butt weld: It is used to connect the parts which are nearly linear and does not overlap.
3.) Girth weld: It is a complete circumferential butt weld joining pipe or components.
4.) Seam weld: The longitudinal or helical seam in pipe, made in the pipe mill for the
purpose of making a complete circular cross-section.
18
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.2.4. Cathodic Protection - There are two main types of cathodic protection systems:
galvanic and impressed current.
5.2.4.1. Galvanic system: Makes use of the corrosive potentials for different metals.
Without CP, one area of structure exists at a more negative
potential than another, and corrosion results. If, however, a much less inert object (that is, with
much more negative potential, such as a magnesium anode) is placed adjacent to the structure to
be protected, such as a pipeline, and a metallic connection (insulated wire) is installed between
the object and the structure, the object will become the anode and the entire structure will
become the cathode. That is, the new object corrodes sacrificially to protect the structure.
Galvanic anodes are usually made of either magnesium or zinc because these metals have higher
potential compared to steel structures.
5.2.4.2. Impressed current systems: Use same elements structure and is protected by
applying a current to it from an anode. The anode and the structure are connected by an insulated
wire and current flows from the anode through the electrolyte onto the structure, just as in the
galvanic system. The main difference between both systems is that the galvanic system relies on
the difference in potential between the anode and structure, whereas the impressed current
system uses an external power source to drive the current. The external power source is usually a
rectifier that changes input A.C. power to the proper D.C. power. Impressed current cathodic
protection system anodes typically are high-silicon cast iron or graphite.
5.3.5. Construction Stages
Table 12 – Pre-Construction Activities
19
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Table 13
Table 14
20
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.3. District Regulating Station
DRS are the device used to reduce the pressure from 25 bars to 4 bars. It is the interface between
the steel grid network and medium pressure network. It is located at various demand centers for
domestic /commercial users and typically consists of:
1.) Gas Filter
2.) Heater, if required
3.) Pressure reduction (active / monitor combination) skid with minimum 50%
redundancy including slam shut valve for over pressure protection.
4.) Inlet and outlet isolation valves.
The flow capacity of DRS is in range of 5000-10000 SCMH. The inlet line of DRS is steel
pipeline and outlet is polyethylene pipeline carrying a pressure of 4 bars.
21
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 10 – Inside view of DRS
5.3.1. Pressure Reduction Valve
The pilot (2-stage) reduces the inlet pressure Pe in two stages and provides constant motorization
pressure Pm to operate the main regulator. In the absence of pressure the plug 5 remains in the
closed position by the spring 16, and soft seating Disc4 rests on the seat 3. The upstream
pressure, even if variable, does not change this position as the plug is balanced and is therefore
subject to equal pressures, even if the sections are different. The upstream pressure is passed
through the hole in plug rod 18 to other chamber of plug, equalizing the pressure on both sides.
The plug movement is controlled by the diaphragm 10 by the following forces acting on it:
1.) Downwards: the force of spring 16, the thrust deriving from the regulated pressure Pa in the
top diaphragm chamber and the weight of the diaphragm assembly;
2.) Upwards: the thrust deriving from the motorization pressure Pm in the bottom diaphragm
chamber, supplied by the pilot.
22
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 11 – Functioning of a PRV
 The motorization pressure is obtained by drawing gas from regulator at the u/s pressure.
 Filter 41 filters gas and is subjected to initial reduction in the first stage pilot, composed
essentially of a plug 37, a spring 28 and a diaphragm 34A to a value, which depends on
the pressure set point of the regulator.
 The pressure then passes to second stage pilot that controls pressure by plug 35, a main
spring 28 and a diaphragm 34B to the motorization pressure Pm, which is supplied to
bottom diaphragm chamber of the main regulator.
 The regulation of Pm is obtained by the comparison of the force exerted by setting spring
28B of the pilot and the action of the regulated pressure Pa, acting in the chamber below
the diaphragm 34B.
5.3.2. SSV/SDV (Slam Shut Valve/Shut down Valve)
23
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 The control mechanism (Pilot 1) has a latching arrangement holding main valve stem in
open position. The sensing element is pilot regulator (Pilot 2) continuously monitors the
line pressure to be safeguarded.
 This pilot spring diaphragm type valve, in case of over pressurization gives signal
pressure to control mechanism which in turn trips off main valve.
 In normal condition the Pilot-2 remains in close position. The main valve remains in open
position by holding the plug rod 14 by rack 21 through ball catch arrangement in Pilot-1.
 Whenever the pressure monitoring by Pilot-2 exceeds above its set intervention value the
diaphragm 48 moves upward displacing the plug 47.
 Thus the pressure passes to Pilot-1 diaphragm 27 pressing it along with push rod 25,
pressing the ball 41.
 The rack 21 latched by the ball gets released resulting in downward movement of plug 7
and plug rod 14 closing the valve. The visual indicator 32 will indicate the position as
CLOSE.
 The valve can also be shut off manually by pressing knob 33 on pilot-2.
24
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 12 – Functioning of a Slam Shut Valve (SSV)
5.3.3. CRV (Creep Relief Valve)
The controlled pressure is generally set to a pre-determined designed value using adjusting
screw. This is the maximum pressure which pressure-gauge (installed on upstream side of control
valve) indicates when the fluid is not flowing through the valve. Any accumulation of the gas
results in increase in controlled pressure. This result in increase in the compensation force, which
balances the controlling force, hence valve opens. This releases the rise/build up in the upstream
pressure. Thus, it is clear that the pressure will not be the same during no-flow and during flowpassing through valve. Hence rise in the controlled pressure, during operation/flow through the
valve, is to be accepted in principle and one should not try to re-set the valve/pressure because of
the draw of fluid. The controlled pressure is expected to rise to allow for discharge to the
downstream side of the valve.
25
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 13 – Functioning of CRV
5.3.4. Non Return valve (NRV) - It is also known as check valve. It maintains
unidirectional flow and restricts reverse flow. It operates by itself by application of pressure
present in line, minimum pressure range is required to operate this valve.
Its functioning would be discussed later.
5.4. Secondary Network – MDPE Pipeline
A. The distribution pipe is with standard dimension ratio (SDR 9) for 20 mm, (SDR 11)
from 32 mm upto 63 mm and (SDR 17.6) for above 63 mm. The term SDR is defined as
the normal outside diameter (DN) divided by the minimal wall thickness.
B. It is standard practice in India to have a minimum 1 m cover. All MDPE Pipe back filled
with sand around it to protect the plastic material.
26
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 14 – MDPE Pipeline
5.4.1. Specifications




Tech. Spec.: IS 14885:2001 & ISO 4437
Material Grade & Color: Internationally approved resins of PE 100 grade of Orange color
Minimum Required Strength (MRS) of PE 100 Grade pipe: 10 MPa
Operating Pressure: 4 Bar, Operating Temperature Range: -10°C to +40°C
5.4.2. Advantages of MDPE Pipelines
 High Performance (Globally proven leak free system), more flexibility, coil ability,
ductility, high elasticity.
 Low Density (low weight, high strength to weight ratio).
 High resistance to corrosion and Low Heat Conductivity (low thermal loss).
 Smooth surfaces (low pressure losses due to low pipe friction)
 Reduced number of joints, hence safer and leak free system.
 Less time is consumed to repair PE Damages as compared to steel damages, Avoidance of
NDT techniques in building premises, which is very critical.
 Size of trench is less in case of laying of PE Pipe as compared to steel.
5.4.3. MDPE Fittings
27
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 15 – Stem extension type valves and MDPE Fittings




Tech Spec. : ISO 8085-3 or EN 1555-3
Material Grade: PE 100, Color: Black
Terminal Pin Size: 4 or 4.7 mm
Voltage: 39-40 Volts.
5.4.4. PE Stop Off Valves









28
Standard: ASME B16.40, EN 1555.4
Pressure Class: SDR 11
Design Pressure: 5.5 Bar
Design Temperature: 45°C
Operating temperature: 10°C to 45°C
End Connections: PE Material
Stem Extension: Min. 690 mm from top of the pipe.
Valve Design: One piece Construction
Ball Position Indicator: Open/Close limits required.
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.5. PE Laying
‒MP Network
1. The MP PE network starts from downstream of DRS/CPRS and distributes the Natural
Gas till the different Service Regulator located nearby a cluster of domestic customers or
a main commercial customer or Industrial Customers upto MRS/IMS.
2. The PE mains are subdivided into sections by means of adequately located manually
operated valves (Note: As per PNGRB in MP network minimum one at every 1 Km).
‒LP Network
1. The LP Network in PE starts from the downstream of Service Regulator (SR) and brings
the natural Gas to domestic customers.
5.5.1. PE Laying Process for Open Cut Excavation:
1. Preliminary route survey as per GSPC GAS planning drawing.
2. Line marking before excavation work.
3. Trench depth to maintain 1.0 meter. Cover.
4. To check underground utilities with a minimum clearance of 25cm. from PE pipe. If not
maintain min clearance distance to cover pipe by using RCC half round / PVC sheet.
5. When two PE pipeline (MP & LP) to be laid in same trench then min. 300mm distance to
be maintained between two pipes. Also MP pipeline is to be laid at Road side and LP
pipeline to be laid at extreme side of the road.
6. Pipe laying at the center of the trench for proper sand padding surrounding PE pipes.
7. 75mm sand bedding below pipe in case of normal soil and 150mm in case of rocky
terrain and 75mm sand padding above pipe.
8. Stone free soil backfilling above sand padding upto 0.5 mtr. Of PE pipes.
9. Laying of Warning tape at 0.5 mtr. Depth from ground level
10. Backfilling entire Trench, Watering and Compaction, Excess soil scrapping.
29
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 16 - Trench Dimension for PE Pipeline: Size – 32mm. Similar for other Pipe Sizes
Figure 17 - Safe distance for Excavated soils storage/ Barricades
5.5.2. PE Laying Process for Crossing of River/Water Canal/ National
Highway / Four-lane state Highway and Railway:
i.
No EF joints shall be allowed in PE pipes in major crossings as mentioned above. If the
pipe dia. requirement is higher than 90mm then steel pipeline shall be used in major
crossings by providing Transition Fittings at both ends.
ii.
90 mm dia. PE pipes can be used without any EF joint in between if the crossing length is
less than 100 mtr.
30
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.5.3. Electrofusion Jointing
I.
The pipes ends to be welded must be cut at right angle by using proper pipe cutters.
II.
Visually check that the pipe/fitting surface is free of defects such as cuts, abrasion etc.
III.
Avoid using excessive ovalized pipes. Remove Ovality by using Re-round tool. Clean the
pipe ends from dust, grease, dirt etc.
IV.
Mark the scraping area with an indelible marker pen. The scraping area must be 10mm
larger than the insertion depth of the fittings.
V.
Remove the oxidized surface from the pipe, by scraping it. Remove an uniform surface
for a depth of approximately 0.1mm for pipe diameter upto 63mm and 0.2 mm for pipe
diameter higher 63mm.
VI.
AVOID ABSOLUTELY other scraping equipment such as abrasive paper, rasp, emery
wheels, saw blades, etc. other than Mechanical/Manual scrapper.
VII.
Before inserting the fitting on the pipe, clean the scraped surface using isopropyl alcohol.
VIII.
Clean with the same chemical the inner surface of the fitting, which has to be removed
from its protective wrapping only at the moment of use.
IX.
Do not touch with hands the just cleaned surfaces.
X.
The aligning clamp must be used for all diameters to be welded which, Protects, during
the electro-fusion and the subsequent cooling, mechanical stresses on the jointing.
XI.
Allows revising possible off-centering between both ends to be welded and to recover the
out-of-round of parts, it ovalized.
XII.
In case of EF coupler welding, sign a mark using an indelible pen on the two ends to be
welded corresponding to the depth of insertion, equal to half length of the coupler.
XIII.
Insert the coupler up to the location mark and fasten the pipe into the aligning clamp.
XIV.
Connect the plugs of the control unit to the terminals on the fittings and proceed with the
set-up of the welding parameters, strictly following the instructions of the welding unit.
XV.
When the fusion cycle is completed, verify the fusion indicators coming out. The fusion
indicators are located near the terminal connection of the fitting.
XVI.
Cooling, in order to avoid possible stresses on the jointing, strictly respect the cooling
time indicated on the bar-code and do not remove aligning clamp of the fittings.
31
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.6. Service Regulator
These are installed before tertiary PE lines, generally located at customer premises for
maintaining supply pressure and designed to maintain safe condition even in the event of rupture
in the regulating downstream section. It reduces the pressure from 4 bars to 110 mbar to the
service device.
Table 15
5.6.1. Selection of Location for Installation of SR
1.) Private premises: If possible, immediately after entering and adjacent to boundary wall of
private premises. The best suitable place is Foot-Path, if available nearby.
2.) Min. Distance to be maintained - 10.0 Mtr. from any turning / junction of the road, 15.0 Mtr.
from Bus stand or public gathering spot, 15.0 Mtr. from any above ground electrical installations
i.e. Transformer, Junction box, Pole etc.
3.) Water logged area, In front of Entry / Exit of building / Shop/Garbage collection area is avoided.
5.6.2. Installation of SR
A. Installation of Service regulator module shall be done as per the foundation drawing
/specification.
B. 90 degree EF elbow shall be used for hook-up of the Service Regulator for 63mm and
above size pipeline.
32
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
C. Installation of Service Regulator should be in such a position that Flow direction of
Service Regulator and gas flow in pipeline is in the same direction.
D. Golden yellow color shall be applied on foundation of Service Regulator.
Figure 18 – Service Regulator.
5.6.3. Testing of SR
I.
Pre-commissioning testing for performance of safety devices i.e. UPSO, OPSO, and
Relief valve, which is integral part of Service Regulator, shall be done.
II.
The set pressure of Service Regulator for different features are as per the below:
–Set Pressure: 100 – 110 mbar
–UPSO: 50 mbar
–OPSO: 150 mbar
- All electro-fusion joints (SR Hook up joints) shall be checked with soap solution before
commissioning of Service Regulator.
5.6.4. Commissioning of SR
A. Ensure all installation and pre-commissioning activities are completed. Inlet and Outlet
valves shall be kept in closed position.
B. Gas in upto inlet valve of Service Regulator by opening of Valve/squeeze tool.
33
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
C. Leak test shall be carried out upto upstream of inlet valve. If no leakages found, open
inlet valve of Service Regulator and ensure no leakages upto outlet isolation valve.
D. Monitor Outlet pressure of Service Regulator for 5 min. before opening outlet valve.
E. Ensure positive lock-up pressure (to confirm no leakages or open end during
commissioning) in downstream network before opening outlet valve.
F. Ensure that not a single domestic connection has been connected through downstream of
the network which is to be commissioned.
G. Release lock up pressure before opening outlet valve of SR and by keeping inlet valve
closed.
H. Slowly open inlet valve first and subsequently outlet valve of Service regulator to allow
Gas – in the downstream network.
5.6.5. Installation of PE Valve
A. Isolation valve to be installed at every 1.0 km on 90mm dia. and above PE pipeline
Medium Pressure network. Where tapping of 90mm and above on Medium Pressure PE
network, PE isolation valve to be provided immediate after tapping.
B. Isolation valve to be installed before 2.0 meter of end cap for 125mm and higher dia.
Medium Pressure PE pipeline.
C. The valve shall be supported on a bed of firmly compacted by using fine sand.
D. Ensure proper installation/alignment of PE valve. Ensure proper PCC prior to installation
of Pre-cast chamber of Valve.
E. Isolation valves shall be provided in PE pipe line at both ends of major crossing carried
out with Steel pipeline.
5.6.6. PE Testing
5.6.6.1 MP Network Testing: The MP Network will be tested at 7.0 bars for
A. PE distribution mains of length greater than 1 Km for at least 24 hours.
B. PE distribution mains of length shorter than 1 Km at least 6 hours after pressure
stabilization and the pressure gauge must measure an unchanged pressure during test
duration. The test medium shall be air or nitrogen.
34
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
C. Suitable Relief Valve set at 5% higher than i.e. 7.9bar test pressure shall be fitted at the
test to avoid over pressurization during testing.
D. The DRS/CPRS, Service Regulator and service line must be disconnected during testing.
The section to be tested must be completely isolated.
5.6.6.2 LP Network Testing: The operating pressure of LP network is 110 mbar.
The procedure to follow the pneumatic testing and flushing of a LP network is similar to the
procedure for the MP network. Except for the following:
A. The LP network also must be tested at 7.0 bars for 6 hour.
B. The Contractor will test network by section starting from the Service Regulator till all the
sections of the concerned area have been tested satisfactorily.
5.6.7. PE Pipeline Marker
A. Pipe line marker shall be installed at every 200 mtr. distance on sizes of 63mm and above
PE pipelines. Also pipe line marker shall be installed at both sides of Main road crossing,
river crossing, railway crossing and any other locations as specified by GSPC GAS.
B. Marker installation shall be done as per GSPC GAS approved diagram. Ensure marking
on Pipeline Marker is as per approved drawing of GSPC Gas. Installation of Pipeline
route marker as per approved drawing of GSPC Gas.
5.6.8. Commissioning
A. To check the hot work permit.
B. As laid PE Network drawing / schematic of the section to be commissioned and existing
end cap showing vent point.
C. Ensure pneumatic test report. Check and assure that the positive pressure in the pipeline
stayed equal as the pressure measure after testing.
D. Calibrated pressure gauge is used.
E. Ensure that EF welding machine with ELCB (Earth leak circuit breaker).
F. Ensure availability of additional Squeeze tools for emergency.
G. The gas should be vent continuously by crack opening of valve until two reading confirm
a concentration of gas by methane detector.
35
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
5.7. Industrial Metering Station (IMS)/MRS
A. They are used to measure the gas supplies to Industrial customers. The main components
in IMS is filter, Isolation Valves, RPD Meters, Regulators (if low pressure requirement)
and Non Return Valve.
B. Inlet Pressure Range – 1.5 Bar to 4 Bar, Outlet Pressure – As required by customer.
Figure 19 – Industrial Metering Station
Main Components of IMS
 Filter - It is also a cartridge type filter with pore size of 5 microns.
 Gas meter - Volumetric gas meter is used here.
 NRV - It allows one way flow as discussed above.
 CRV - It is used here to relief excess pressure in line in case of over pressure.
 PRV in customer premises - Same as PRV in CGS skid and CPRS skid it
reduces pressure as required. It operates without pilot valve.
36
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Chapter 6 – PNG Installation
6.1. Domestic and Commercial / Non-Commercial PNG Connection
- The connection between consumer meter set assembly and gas appliance may be made by GI
Pipes or Copper Tubing or Steel Rubber Hose.
- Commercial Connection has same components as domestic connection but some customers
may have larger diameter GI Pipeline and higher pressure meter.
- The quantity of gas consumed by an average domestic consumer will remain almost same for
all customers. Basic data sheet is prepared based on practical assumption & past experience of
similar gas distribution industries. For estimating/calculating the peak demand of domestic
consumer we consider following assumptions.
6.1.1. Design of vertical risers:
 Apartment connections can be classified into the following category:
- Single connection (kitchen) per riser on each floor.
- Two connections (kitchens) per riser on each floor.
- ½‟‟GI pipe riser up to 7 floors for one connection on each floor.
- ½” GI pipe riser up to 3 floors for two connections on each floor.
 1” GI pipe riser for connecting more than seven floors and up to sixteenth floor from
single riser & single connection on each floor.
6.1.2. For Horizontal common approach pipeline
 ½” GI pipe common approach, maximum five connections to be connected.
 1” GI pipe common approach, more than five up to twelve connections to be connected.
6.1.3. Route Selection
 Pipe shall not be installed on un-plastered wall or in the house under construction or in an
unventilated void space.
 Route shall be selected that maximum length of the pipeline shall be installed outside.
Route of the pipeline shall be planned for the shortest possible length.
 The gas pipeline and meter shall be away (minimum distance of 300mm) from the
electrical line and heat source. There shall be minimum change of directions and
minimum no of threaded joints.
37
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 Maximum two Point in the single kitchen for gas stove only.
 Compound gate or doors and windows inside the house shall not hit the Gas pipeline, if
no alternative route found installs proper pipe protection guard.
6.1.4. Positioning of Valves, Regulator & Meter:
 Riser Isolation Valve: For apartments, one riser isolation valve shall be provided at a
height of 2 meter from the ground level.
 Customer wise individual main isolation valve shall be installed. Brass made Regulator
and Meter adaptor shall be used.
 Regulator shall be installed in such a way that it reduces the length of H.P. Line (Max.
pressure 0.1 Bar) to minimum possible. Wherever possible meter Regulator shall always
be installed outside residence and at a convenient height.
 It is advisable to install Gas Meter shall in such a way that it shall be protected from
direct rain or waterfall on the meter. Location of the Gas meter shall be decided during
the route selection.
6.1.5. Appliance Valve:
 The position of the appliance valve shall be convenient to operate and it shall keep the
rubber tube at a safe distance from the heat source.
 The orientation and distance from cooking platform/ground shall be maintained in such a
way that the Bending Radius of the Rubber Tube shall be more than 100mm.
 Appliance valve shall be installed in ventilated space and the lever of appliance valve
shall not foul with the wall during the on-off operation.
6.1.6. GI Pipe cutting & Threading:
 After site and route clearance, the measurements for pipe cutting shall be taken and pipes
shall be cut accurately as per the required lengths.
 Installed piping threaded connections / joints shall be tightened in such a way that all the
joints shall be free from heavy stresses and misalignments due to incorrect pipe length.
Cutting fluids (oils) shall be used while thread cutting.
38
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 The condition of thread die and pipe vice jaws shall be checked regularly and shall be
free from defects. BSP taper thread dies to be used for threading and shall be checked
with “GO” and “NOGO” gauge.
 Threaded pipes shall be handled carefully so that the threaded oily portion shall be free
from dust, mud, water and any damage due to impact of any object.
 Cutting burrs on the pipe shall be removed from the edges. The edges shall be straight
and free from Knife-edge formation.
6.1.7. G.I. Pipe Installation & Clamping:
 Teflon tapes of approved make shall be wrapped on threaded portion of the pipe with
minimum three overlaps.
 The pipeline portion containing the Regulator and Meter, either horizontal or vertical,
shall have clamps on both side of the regulator and meter. Clamps shall be fitted in such a
way that they do not create misalignment of pipes.
 The clamp shall be installed by drilling 6 mm hole in plastered wall and screwed using
rowel plug. The clamps should be fixed properly on the walls and grip pipe in position.
 Distance between two clamps shall not be more than 1.0 meter. Clamps shall be installed
in a straight line and shall be parallel to each other.
 Self-adhesive anti-corrosive tape shall be wrapped on the pipe with 50% overlap. Casing
sleeve shall be installed in wall for wall crossing.
 Wherever compound gate, house door or window may hits the G.I. pipe, protection clamp
shall be installed to protect the pipe. Concealed piping shall not be done.
 All the pipes shall run on walls with clamps. Pipe should not be overhung and shall not
be installed without pipe clamp.
 PE to GI (transition fitting) threaded joint shall be provided above ground. PE pipe length
should be 1.5 meter of transition fitting.
39
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 20 – GI Clamps to Pipe on Wall
6.1.8. Testing of Installed Piping Connection:
 Before carrying out the pneumatic test of the whole installation; testing assembly, air foot
pump with pressure gauge / manometer shall be checked its calibration and proper
functioning.
 Before pneumatic testing of the installed connection spacing between two clamps,
tightening of the clamps thread joints, alignments of the whole piping shall be checked.
Valve shall be kept in open position and the appliance valve shall be kept in close
position.
 Calibrated pressure gauge shall be used having the range of 0 – 1 Bar. Position of the
pointer of the pressure gauge shall not be marked with the marker pen on the glass. It
should be recorded in the test records.
Table - 16
S. No.
Type of Testing
Test Pressure
Duration
1.
Pneumatic Pressure
Testing (PPT)
MMT
Riser Testing
3.5 Kg/Cm2
30 minutes
Gas Pressure
3.5 Kg/Cm2
15 minutes
1 Hour
2.
3.
 After pressurization of the whole piping section shall be checked for the leakage with the
help of soap solution.
 During the testing, air should reach up to the appliance valve. After completion of testing,
pressurized air shall be released from appliance valve only.
6.1.9. Conversion of Burner
40
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 All the appliance valve and riser isolation valve shall be kept in closed position. Ensure
that meter and regulator adaptor shall be leak proof.
 Open the burner knob and remove the plug from the hot plate.
 Clean the simmer hole. Make the simmer hole of 0.6 mm with the help of simmer drill.
 At the time of drilling the hole, ensure that it should not be inclined. Remove the dust
from plug.
 After greasing, plug and knob should be properly positioned at their original position.
 Remove the burner from hot plate and clean it. Open the existing jet (LPG) and replace it
by 125 no jet if it is big burner or 110 no jet if it is small burner.
 Place the burner on its original position and connect the nozzle with appliance valve
using flexible and braided SURAKSHA rubber hose.
 The length of rubber hose shall not exceed 1.0 mtr. Both the ends of the rubber hose shall
be clamped by metallic clamps on the nozzle.
 Check all the joints with soap solution and ensure that the flame color should be blue.
6.1.13. Meter Job Card
Meter Job card to be prepared duly signed by Contractor, Customer & Third Party Inspector and
to be submitted to GSPC Gas immediately on completion of conversion.
41
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 21 – Schematic Diagram of a Domestic PNG Connection
6.2. Industrial Connection:
 Natural Gas Requirement identification: A format consisting of equipment details
and fuel consumption pattern to be furnished by
customers to finalize the size and type of MRS and for the agreement with customers.
6.2.1. Scope of work of GSPC Gas Co. Ltd.:
I.
Finalize the location of Industrial Metering Skid as per safe installation distance:
Table - 17
Reference Location
Distance of IMS Installation
Electrical Transformer
Open flame or furnace/ any gas fired
12 meter
15 meter
42
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
equipments
Boundary wall
Bore well or sock pit/underground septic tank
2 meter
6 meter
- Battery limit of GSPC Gas and Industrial customer is as follows:
Figure 22 – Scope of Work of GSPC Gas for Industrial Customer.
6.2.2. Scope of work of Industrial Customer:
6.2.2.1. Skid Location/layout:
I.
Appropriate location and space for installation of IMS to be provided by customer.
II.
Preparation of foundation to be done as per Foundation drawing.
III.
Installation of mounting pole to be done by customer within 3 to 5 meter from IMS.
IV.
Installation of brick Chamber near hook up portion of skid and filling with fine sand to
protect PE pipe as per GSPC Gas requirement.
V.
Chain link fencing to be done surrounding the Industrial Metering skid for restricted unauthorized entry. Minimum distance to be maintained 1.5 meter from the foundation.
6.2.2.2. Internal piping and accessories:
I.
Installation of above ground Piping downstream of the Industrial Metering skid by
customer as per GSPC Gas specifications.
II.
Supply and Installation of Regulators, Isolation valves, pipe fittings, fasteners and
consumables shall be done by the customer as per individual equipment flow and
pressure requirement.
43
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
III.
Supply and installation of Gas train with safety interlocks, Gas Burner and equipment
conversion. Pneumatic testing of Internal Piping.
6.2.2.3. Electrical:
I.
Un-interrupted AC power supply for Metering purpose and two separate earthing for IMS
to be provided and done by customer.
6.2.3. Installation of Internal Piping:
I.
Internal piping installation shall be done through competent steel pipeline contractor.
II.
Underground steel pipeline shall not be allowed inside the premises.
III.
Jointing of Internal piping shall be done through welding method only. No threaded joints
shall be allowed for internal piping installations. Welding spatter should be removed by
grinding.
IV.
Pipe should not be routed through heated zone like bhatthis / tandoor / furnace etc. For
wall crossing the pipe should be protected with anti-corrosive wrapping tape.
V.
All pipe work should be horizontally and vertically aligned.
VI.
Pipe support should be firmly fixed on wall and Pipe should be firmly tightened on
support with U bolt or to be installed on proper fabricated structure on ground.
VII.
Pipeline shall not rest on support directly. Rubber sheet piece to be kept between pipe and
support to avoid erosion and leakage.
VIII.
A safe gap of minimum 1" should be maintained between pipe and wall. Pipe support
should not be provided on temporary wall/shed/trees etc.
IX.
Main Isolation Valve to be provided immediately after entering into industrial premise
and branch Isolation ball valve at each tapping from main header.
6.2.4. Testing:
I.
Pipeline should be flushed with air or nitrogen to remove dust, dirt, welding spatter etc.
Meter and regulator should be removed before flushing. Flushing should be done from
each tapping.
II.
Once flushing is completed entire pipeline shall be tested at min. of 1.5 x design pressure
(MOP) or 7 bar whichever is higher with air or nitrogen for 06 Hrs. Testing shall be done
with all isolation valves semi open. Pressure should not drop during testing hours.
44
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
III.
Once testing is found OK, pressure should be vented out till pipeline pressure becomes
0.5 bars. Positive pressure shall be kept hold till pipeline commissioning.
IV.
Once testing is OK a testing certificate to be submitted by customer to GSPC Gas.
6.2.5. Painting:
I.
Selection of proper paints to be made depending on the environment conditions.
II.
Entire pipe should be cleaned with wire brush. It should be free of welding spatter, dust,
dirt, rust and moisture.
III.
Painting should be done only after testing is found O.K.
IV.
Primer and finished coat shall be done as per paint manufacturer recommendations. Final
coat shall be “Golden Yellow” color for gas pipeline identification.
V.
Direction of gas flow should be marked along the pipeline at the interval of 2 meters.
6.2.6. Safety Requirements:
I.
Location of Industrial Metering Skid as per safe installation distance with various
references.
II.
Portable Fire Extinguisher of ABC type -10 kg. (ISI marked) to be placed nearby
Industrial Metering skid by customer before commissioning of Internal Piping.
III.
“NO SMOKING”, Safety Instruction Board and other safety signage near Industrial
metering Skid.
Customer internal piping with electrical bonding at joints.
IV.
V.
Any modification/alteration after commissioning of internal piping shall be done only
after prior intimation to GSPC Gas.
VI.
Intimation to GSPC Gas in case of plant shutdown/ No usage of NG for long time.
6.2.7. Pre-Commissioning of Industrial Metering Skid:
I.
GSPC Gas engineer shall ensure undertaking from customer for successfully testing of
internal pipeline on their letterhead.
II.
GSPC Gas representative need not to certify testing of customer premises internal piping.
III.
Pre-commissioning check list shall be filled before IMS commissioning.
6.2.8. Commissioning of Industrial Metering Skid:
45
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
I.
GSPC Gas engineer shall ensure undertaking from customer for successfully internal
pipeline testing on their letterhead.
II.
Tool-Box talk shall be conducted in presence of Industrial customer covering Do’s and
Dont’s.
III.
Ensure positive lock pressure in internal piping before opening of Industrial Metering
Skid outlet valve to industrial customer.
IV.
Ensure internal piping of Industrial metering skid up to equipment connected before
commissioning of metering skid, and no inter connection with other fuel system.
V.
Ensure oil level in case of RPD meter before Industrial metering skid commissioning.
VI.
Ensure all required accessories of meter are installed prior to commissioning.
VII.
Ensure GSPC Gas engineer presence during commissioning of internal piping.
VIII.
Industrial Metering skid commissioning report shall be prepared after commissioning.
Chapter 7 – Gas Metering
We are only going to discuss about the major category of Gas Meters used by GSPC Gas in
different Segments, i.e., Domestic, Commercial and Industrial.
7.1. Diaphragm Gas Meter (Domestic & Commercial)
It is having four measuring chambers separated by synthetic diaphragms. These chambers are
filled and emptied periodically and the movement of the diaphragm is transferred via a gear to
crankshaft. And thus shaft moves the valves that measure the volumetric gas flow. Rotations of
the gear are transferred to the index via a magnet coupling, ensuring proper sealing. Ex. Elster,
Raychem etc.
Table -18
Specification
46
Domestic Meter
City Gas Distribution by Sarthak Kishore| GSPC GAS
Commercial Meter
CITY GAS DISTRIBUTION
Tech. Spec
EN 1359
EN 1359
Capacity
2.5 m3/hr.
10,25, 40, 65 scmh
Range ability or TD Ratio
1:150 or better
1:150 or better
Nominal Working Pressure
21 mBar
100 mBar
Domestic Meter: End Connection: ¾” as per BS 746, Center to Center Distance: 110 mm
between Inlet and Outlet Connection.
Commercial Meter: Pressure Rating: Suitable to withstand Max. Working Pressure of 200 mBar
Figure 23 – Domestic and Commercial Diaphragm Meter
7.2. Rotary Positive Displacement Meters (RPD)
It is having a two 8-shaped impeller. These impellers rotate due to pressure difference created by
the gas entering the meter from one end. Timing Gear is present to synchronize the two impellers
to rotate in opposite direction. The gear trains are used to move counter in turn to generate
LF/HF Pulse.
Specifications:
I.
Tech. Spec.: EN 12480
II.
Volumetric Meter, Large Measuring range, Needs lubrication
III.
Appropriate for Medium Size Load
IV.
Typical Turndown 35:1 to 50:1
V.
Accuracy +1%
VI.
Not sensitive against Disturbances, Not sensitive against fast changes against flow rates
47
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 24 – RPD Meter
Chapter 8 – Valves Types and Features
The three basic functions of valves are: 1. to stop flow, 2. to keep a constant direction of flow,
and 3. to regulate the flow rate and pressure. There are various types of Valves used in CGD
Industry. GSPC Gas equipments are mostly consisting of Ball Valves.
8.1. Ball Valves
 They are suitable for gas, compressed air, liquid and slurry device. They are commonlu
used for Isolation services.
 A ball valve shall have a spherical closure member which rotates about an axis which is
perpendicular to the direction of flow. It is easier to obtain a tighter seal with a sphere
than with other shapes.
 The valve shown has flanges end parts, which connect to the piping and are held to the
main body by bolting arrangement. The valve is operated by turning the spherical plug
(ball) a quarter turn in the clockwise (for closing) or anti-clockwise direction (for
opening).
48
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 25 – Flanged End Ball Valves
8.2. Check Valve (Non Return Valve)
 A check valve shall have a closure member(s) (as ball or a flapper) permit fluid to flow in
one direction only. Lift-check and swing-check are the two major types of valves used in
process work.
 The lift-check, or ball-check, is most often used in 2- inch and smaller sizes. It has a ball
or guided plug which is lifted by fluid pressure and does not have a tendency to slam - as
the swing-check type does. For this reason, the lift-check valve is preferable for services
having irregular or frequent reversals of flow.
49
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 26 – Lift Check Valve
 For sizes larger than 2-inch, the swing-check valve is most often used.
Figure 27 – Swing Check Valve
Chapter 9 – PNG O&M (Operation and Maintenance)
The major assets, associated activities and their frequencies as per Operation and Maintenance
Plan (O&M) are as under –
Table - 19
Sr.
No.
1.
Description
PNG Connection
50
City Gas Distribution by Sarthak Kishore| GSPC GAS
Frequency
Responsi
bility
CITY GAS DISTRIBUTION
1.1
1.2
Inspection/ Maintenance of Domestic Connection
Replacement of Flexible Rubber Hose for all points
(No cost for Customer for Single Kitchen Point)
GI Riser Maintenance
Inspection/ Maintenance of Commercial Connection
Annual
Once in 5 Years
1.5
Replacement of Flexible Rubber Hose for all points
(Chargeable to Customer)
Once in 5 Years
2.
CGS/CPRS/DRS/Let Down Skid upto CNG Station
2.1
2.2
2.3
2.4
Monitoring of Pressure/Flow
Leak Check of all points
Valve Operation & Greasing
Stream Changes & Functional Test of PRV/SSV &
CRV
Maintenance of Filters/KOD
Calibration of SRV/CRV
Testing of Gas Detection System
Calibration of Gas Detection System
Checking of Earth Pit and Earthing Electrodes
Painting/Touch up of A/G Piping
Hydro testing of Filters/KOD
1.3
1.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
Calibration of Meter other than Custody Transfer
Meter (PT,TT)
2.13
2.14
2.15
2.16
Calibration of all Pressure Gauge
Environmental Monitoring (Air Pollution Check)
Noise Level Monitoring
Maintenance of Power System and Power Back – Up
2.17
Maintenance of TR Unit, Anode Bed, Reference Cell
3.
3.1
3.2
3.3
3.4
Odorant System
3.5
Monitoring of Odorant Level/Smell
Odorant transfer from Barrel to Tank
Monitoring/Inspection of Odorant Storage area
Leak Check of all joints and at the time of every
odorant filling
Pneumatic Test of Odorant Tank
3.6
Calibration of Pressure Gauge
51
City Gas Distribution by Sarthak Kishore| GSPC GAS
Once in 2 Years
Annual
PE/PNG
O&M Team
Daily
Half Yearly
Yearly
Half Yearly
Yearly
Yearly
Need Base
Variation in
wall thickness
Half Yearly
Yearly
PE/PNG
O&M
Team
Steel
Pipeline
Engineer
Metering
Engineer
Steel
Pipeline
Engineer
Half Yearly
Daily
When required
Half Yearly
If Wall
thickness varies
Yearly
PE/PNG
O&M
Team
CITY GAS DISTRIBUTION
4.
Steel Distribution Network
4.1
4.2
4.3
4.4
4.5
4.6
Patrolling within City/Town area crossing
Patrolling Intra City/Town
LPT Survey of Steel Network
LDT within City
LDT outside City
Preventive Maintenance of Valve Chamber
4.7
4.8
4.9
4.10
Pest Control at Valve Chamber
Operation and Greasing of Valves
Repair of Valve Chamber
Emergency Patrolling & Third party Coordination if
work is going on near gas pipeline route
4.11
4.12
Maintenance of all type of Markers
Repair of Pipeline Coating
Daily
Monthly
Quarterly
Quarterly
Yearly
Pre and Post
Monsoon
Need Basis
Half Yearly
As & When
required
5.
Cathodic Protection System (TCP, ICCP)
5.1
Monitoring of TR
Daily
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
Preventive Maintenance of TR Unit
PSP Monitoring
Monitoring of Insulating Joints
Preventive Maintenance of TLPs
Painting of TLP,AJB,CJB
On-Off Potential Measurement
Calibration of Voltage & Ampere Meter
Maintenance of Battery Tank
Monitoring of Anode Ground Bed (AGB) and
Reference Cell
Half Yearly
Half Yearly
Monthly
Yearly
When Required
Yearly
Yearly
Half Yearly
Half Yearly
6.
Statutory Compliance Monitoring
6.1
6.1.1
6.1.2
Factory Act Requirement
Factory License
Audit Finding Compliance post visit of Factory
Inspector
GPCB Compliance
6.2
52
City Gas Distribution by Sarthak Kishore| GSPC GAS
PE/PNG
O&M
Team
Steel
Pipeline
Engineer
PE/PNG
O&M
Team
Steel
Pipeline
Engineer
PE/PNG
O&M
Team
NA
NA
Steel
Pipeline
Engineer
(Steel
Pipeline CP
Contractor
)
Legal
ZH/GA
CITY GAS DISTRIBUTION
6.2.1
6.2.2
6.2.3
6.2.4
6.2.5
6.2.6
NOC
Air Consent, Water Consent
Authorization for Hazardous Waste Disposal
Submission of Monthly Monitoring Reports to
GPCB
Submission of Annual Environment Reports to
GPCB
Annual Return of Hazardous waste dispatched
during whole year
Once
Half Yearly
Half Yearly
HSE
Yearly
Figure 28 - Pressure Profile of CGD Network
Chapter 10 – CNG Distribution System
I.
CNG Refueling Station is a facility set-up for supplying CNG mainly as a fuel to
vehicles. The system receives odorized gas at certain pressure (3-19 Bar), through
53
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
transmission line and supplies the same to the customers/vehicles after filtration,
compression (upto 250 Bar) and check metering.
II.
CNG is stored at compression stations which are directly connected with the gas pipeline.
Here the gas is compressed to a required pressure and aids fuelling. CNG can also be
transported to other retail outlets by cylinder trucks. These trucks carry a number of
cylinders which provide CNG to fuel stations which are not connected by pipelines.
III.
The system has major assets like, Odoriser Unit, CNG Compressor, Storage facility,
Dispenser, LCV/HCV Filing Point, Mobile cascade vehicle, Electrical Installations, DG
set and Air Compressor. The size, rating and type of the major and sub assets are selected
based on the pressure rating, capacity and other applicable criteria considered for
refueling station for meeting the current and future customer potential, health and safety
of employees, customers and public at large, environmental protection and complying the
statutory, legal requirements, national and international technical and safety standards/
practices.
IV.
Various operation and maintenance activities, as per annual operation and maintenance
plan are carried out for ensuring safe and uninterrupted gas supply.
Figure 29 – CNG Station
10.1. Types of CNG Refueling Stations
54
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
1. Mother Station: A CNG station provided with whole set up (compressors, dispensers,
cascade etc.) along with a LCV filling point is known as a mother a CNG station.
2. Online Station: This CNG station has same set up as a mother station but LCV connection is
not provided for filling.
3. Daughter Booster Station: Daughter station provided with the compressor (known as
boosters) to compress the gas we are getting from the mother station are known as daughter booster
station.
4. Daughter Station: Daughter stations are established in those areas where laying a pipeline is
not possible. In that case gas is delivered from mother station to daughter station; via mobile cascade
van. The gas from mother station is filled in mobile cascade by a LCV filling point.
Figure 30 – Types of CNG Station
10.2. Working of CNG Station:
55
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
10.2.1. CNG Compressor
 Steel line of 2 inches dia. coming to compressor as a suction line (25 bars). Suction line is
provided with isolation valve followed by a strainer for removing of foreign particles.
 After strainer comes the suction filter of size 5 micron. From here the suction line is
divided into two lines, one is inlet to 1st stage of compressor and another one is
instrument line for operating actuator valves in the compressor.
 Instrument line having a pressure of 25 bar it goes to a PRV which reduces pressure upto
6-8 bars for the SOV which provide functioning of actuator.
 Now the main suction line goes in Non Returning Valve (NRV) which provides only
forward movement of gas. From NRV it goes into Blow down Vessel. We have two
interconnected Blow down vessels. In these, gas is stored which is mainly used during
startup of compressor.
 Now from NRV it comes to main PRV & then first Suction volume bottle. From here it
enters to compressor.
 Valve and Piston means in other compressors valve and piston are provided separately
but here valve is provided in the piston so function of both is performed by piston only.
 The first stage is double acting stage; here compression is affected from both the ends of
the cylinder of the compressor. Then gas is sent to the intercooler for the cooling of the
gas.
 Now gas from intercooler enters to second stage for the compression and again same it
goes to intercooler for air cooling of the compressed gas.
 Finally it reaches to third stage for final compression from intercooler for the desired
final pressure of gas. At every stage, the gas pressure and temperature is:
Table -20
 After third stage compression from intercooler it comes in discharge line.
56
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 Lubrication oil is provided for piston and crank case separately.
- Oil SS220 for lubrication
- Oil SS150 for Crank Case
 Final discharge line goes to separator first and then filter of size of 1 micron. Now gas
enters to mass flow meter for measurement. Water cooling is provided for the cooling of
the oil used in compressor. From mass flow meter gas comes to priority panel.
Figure 31 – CNG Compressor
Gas Compressor Specifications:
The following codes and standards (version/revisions valid on the date of order) are referenced to
& made part of specification API-11P (latest edition), API 661:1997, ASME VIII Div. 1999, API 618
BS 5514 - 1996.
ISO 3046/1
NFPA-37, OISD 179 and NFPA-52: 1995 or equivalent.
NFPA- 12, IS: 6382, Gas Cylinder Rule-2004
IS: 5571, IS: 5572, IS: 5580
Indian Electricity Rules, Indian Explosive Act
Standard specifications of Bureau of Indian Standards
Specification/Recommendations of IEC
10.2.2. Safety Units in Compressor
57
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION





Flame detectors and Gas detectors
CO2 flooding system
Vibration Switch
FSLL(Flow Switch Low)
SRV
10.2.3. Priority Panel
 Discharge line coming out from the compressor is splitting into five lines in sequence as:
1. Direct line which is directly going to dispenser high pressure bank.
2. High pressure line directly going to cascade high pressure bank.
3. Followed by medium pressure line divided into two lines one goes to cascade and
other to dispenser medium pressure bank.
4. Followed by low pressure line divided into two lines one goes to cascade and
other to dispenser low pressure bank.
5. Last line is provided for the mobile cascade filling.
 Each line is provided with Non returning valve and pressure transmitter respectively.
Priority system having the following set points:
- High Bank - 220 Bar
- Medium Bank – 210 Bar
- Low Bank – 200 Bar
 Each Bank diverts comp. discharge to Lower side in sequence:
1. Auto Start 190 Bar at High Bank priority
2. Auto Stop at 245 Bar at all 3-Bank priority
10.2.4. Cascades
 A bank of cylinders used for buffer stock of compressed natural gas is known as cascade.
Stationary cascade is used to store the gas when vehicle is not there at the dispenser then
the gas from compressor flows into a cascade.
 Cylinders in a cascade are divided accordingly as:
- High Pressure Cylinders (HP) - 5 cylinders
- Medium Pressure Cylinders (MP) - 11 cylinders
- Low Pressure Cylinders (LP) - 24 cylinders
58
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 The cascade having horizontal cylinders and sited parallel to other cascade, cylinder
fittings should be arranged so that they do not face cylinder fittings of other cascade.
 Cylinder installed horizontally in a cascade shall be separated from another cylinder in
the cascade by a distance of not less than 30 mm.
 Cascade with horizontal cylinders shall have the valves fitted on the same side within the
cascade opposite to the refueling point and arranged in a manner that any gas leakage is
discharged upwards.
 Cascade/bulk units shall be installed on a firm, compacted, well-drained non-combustible
foundation, in the form of a plinth with the raised edge at 2 M from the front and sides of
the cascade. The cascade shall be securely anchored to prevent floating in case flooding is
anticipated.
 Gas storage facility shall be protected from the effects of the weather by a roof or canopy
designed to facilitate the dispersion of free or escaped gas.
 Adequate means shall be provided to prevent the flow or accumulation of flammable or
combustible liquids under containers such as by grading, pads or diversion curbs.
 Only dedicated trailer, truck or any other vehicle to be used for transportation of CNG
storage units. These units should have lugs fitted for lifting and in no case magnetic
device to be used for lifting purposes.
 The vehicle with the cascade there own, shall be placed with easy access and egress on a
low platform or hard compacted ground, which shall extend to at least another one meter
on all sides and this platform or hard ground shall be under a light roof or canopy.
 The trailers/ vehicle carrying CNG should be made immovable by application of brake
and wheel choke prior initiation of filling or dispensing operation. We have two types of
Cascades:
1. Stationary Cascade: These are fixed cascades established on CNG station for the storage of
CNG. It has a direct inlet from compressor and outlet to line connected
to dispenser.
2. Mobile Cascade: Cascade is mounted over an LCV and it carries CNG from Mother station
to Daughter station or Daughter booster station as per the requirement.
59
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Figure 32 – Cascade Unit
Codes and standards for Cascades:
IS 7285
IS 3224
OISD-179
Gas Cylinder Rules-2004
Indian Explosive Act
10.2.5. Dispenser
Main components of a dispenser:
High, Medium, low bank lines
Gas Filter
SOV
Actuator
Mother Board
Non Returning Valve (NRV), Ball Valve, Pressure Regulating Valve (PRV), SRV
Mass flow meter, Pressure Transmitter
Hose Pipe
Three Way Valve
Hex Nipple, Filling Probe
O-Ring
Working of a Dispenser:
 A dispenser has three banks connection namely:- Low pressure Bank (LP)
- Medium pressure Bank (MP)
60
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
- High pressure Bank (HP)
 Gas from dispenser will dispense in the sequence: - low bank, medium bank and high
bank.
 A PRV is connected to main line coming to the dispenser which is reducing the pressure
for the operation of Actuator.
 For any maintenance work Emergency valves should remain closed.
 It has filters (size of one micron) where oil and other foreign particles are removed.
Figure 33 – Dispenser Unit
61
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Chapter 11 – CNG O&M (Operation and Maintenance)
Table 21 – CNG Station asset, Major activities and their frequencies
Name of
Major
Asset
Major Activities
Daily
Odorization
Unit
Suction Skid
CNG
Compressor
CNG
Cascade
Mobile
Cascade
Electrical
Installation
Air
62
Patrolling
Leak
Check
& Oil
top-Up
& Drain
Leak
Checks
Leak
Survey
Check
List
Check &
Replace
parts as in
Check-List
Leak
Checks
& Filter
drain
Leak
Check
CNG
Dispenser
DG Set
Fortnight Monthly Quarterly
House
Keepin
g
Check
Diesel,
Coolant
and Oil
Level
Leak
City Gas Distribution by Sarthak Kishore| GSPC GAS
Half
Yearly
Yearl
y
Emergency
Valve
Chambe
r
Preventi
on
Check
&
Replace
parts
Check
&
Replac
e parts
Damage or
Leakage Part
Repair
Damage or
Leakage Part
Repair
Damage or
Leakage Part
Repair
Damage or
Leakage Part
Repair
Damage or
Leakage Part
Repair
Damage or
Leakage Part
Repair
CITY GAS DISTRIBUTION
Compressor
Check
and
Check
oil
Level
Damage or
Leakage Part
Repair
Chapter 12 – GSPC Gas HSE Policy and Action Plan
12.1. Various Emergencies - Some of the common circumstances under which an
emergency situation can arise.
I.
A Natural Gas leakage without associated with fire from potential leakage sources e.g.
flange and valves in the DRS, CNG stations (Cascade connections), Valve Chambers,
MRS and customer premises.
II.
A leak from the main Steel pipeline section (15-25 bar pressure) could be well damaging
and requires quick isolation of gas supply.
III.
Any fire in customer premises (not a very credible scenario because of very low pressure
in the domestic section of pipeline) or a fire explosion in the gas/leak.
IV.
Third party Pipeline damage requiring system pressure reduction/isolation.
V.
Preventive shutdown action during any Natural calamities, e.g. flood, earthquake,
epidemic, storm etc.
12.2. Why HSE Reporting is Necessary?
 It enables data compilation and analysis.
 To find out root cause of incident / accident – unsafe process/act/design.
 Identify area of improvements
 To know the reason behind the established Causes
 To prevent Recurrences before they become Recordable or Serious
 For the establishment of new corrective actions
 Improve companies safety culture
63
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 To develop Statistical safety data base
 To learn from the mistakes
12.3. Classification of Emergencies
Level 1
a) Emergency / incident can be effectively managed and contained at the location/installation by
available resources.
b) Has no impact outside the site.
Level 2
a) Emergency / incident cannot be effectively managed and contained at the location.
b) Additional support required.
c) Have potential to effect beyond facilities where external support/ mutual aid required.
d) Likely to be danger to life, environment and industrial assets.
Level 3
a) Emergency / incident with off-site impact, catastrophic.
b) Likely to affect population, property and environment.
c) Control is done by District Administration.
12.4. Various Emergency Plan
On site emergency plan: A responsive plan to contain and minimize the effects due to
emergency within the installations.
Crisis management plan: A well-coordinated comprehensive response plan to contain
crisis that has a potential to cause loss of life, property, environment and provide speedy and
effective recovery by making the most effective use of available resources.
Off-site emergency plan: A responsive plan to control/ mitigate the effects of catastrophic
incidents.
This is prepared by district management based on the data of the installation(s) given by all the
owners.
12.5. Incident Controller
64
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Site Incident Controller (SIC) or Incident Controller - means the person who
I.
goes to the scene of the emergency and supervises the actions necessary to overcome the
emergency at the site of the accident.
- The City Managers / technical in charges at respective locations will be the Incident Controller.
II.
Chief Incident Controller - means the person who assumes absolute control of the
unit and determines the action necessary to control the emergency.
- Respective Zonal Head of GSPC Gas is CIC for GSPC Gas Company Ltd.
Duty Manager - means the Manager nominated from time to time at corporate office
III.
of GSPC Gas at Gandhinagar, on duty, whose role is to provide incident management
support during and outside working hours.
12.6. Actions taken by GSPC Gas to maintain HSE Standards
I.
HSE Policy
II.
HSE Reporting
III.
HSE Manual
IV.
HSE requirement in Scope of work (Tender, Work Orders, Manuals)
V.
Permit to Work ( Hot Work, Cold Work, Working at Height, Boring, Electrical Isolation
and Energization)
VI.
Mock Drills (Table Exercise, Functional Exercise, Full-Scale Exercise)
VII.
HIRA (Hazard Identification Risk Assessment), QRA (Quantitative Risk Analysis)
VIII.
Risk Register
IX.
Safety Competency Training (STC)
X.
Personal Protective Equipment (PPE) – Gloves, Safety shoes & glasses, Face Shields, etc.
XI.
Tool Box Talks, Life Guards (focus on High Risk Activities)
XII.
Site Safety Audits
XIII.
Periodic Review Meeting at Local/Zonal/Corporate Level
XIV.
Recognition & Penalty
65
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
XV.
ERDMP (Emergency Response & Disaster Management Plan) – Each Zone has its own.
XVI.
GPCB Clearance
12.7. ERDMP (Emergency Response Disaster Management Plan)
12.7.1. Objectives of ERDMP
 To define and assess emergencies, including risk and environmental impact assessment.
 To control and contain incidents and their effects within the shortest possible time.
 To safeguard employees and people in vicinity and to minimize damage to property
or/and the environment.
 To inform employees, the general public and the authority about the hazards/risks
assessed, safeguards provided, residual risk if any and the role to be played by them in
the event of emergency.
 To be ready for ‘’mutual aid’’ if need arises to help neighboring unit. Normal jurisdiction
of an OEP is the own premises only, but looking to the time factor in arriving the external
help or off-site plan agency; the jurisdiction must be extended outside to the extent
possible in case of emergency occurring outside.
12.7.2. Essential Features of ERDMP as per PNGRB
 Classification of Emergencies
 Consequences of defaults or non- compliance
 Pre-emergency planning and Emergency mitigation measures
 Emergency preparedness and ER procedures
 Emergency organization and responsibilities
 Declaration of on-site and off-site emergencies
 Infrastructure requirements and Demographic information
 Medical facilities
66
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
 Evacuation through developing Public relation and information to public.
 Incident reporting
 Emergency recovery procedures
 Security threat plan and action plan to meet eventualities
Chapter 13 – CGD Regulations
The Petroleum and Natural Gas Regulatory Board Bill, 2005 establishes the Petroleum and
Natural Gas Regulatory Board (PNGRB) to regulate downstream activities in the petroleum and
natural gas sector. It includes refining, processing, storage, transportation, distribution, marketing
and sale of petroleum, petroleum products and natural gas excluding production of Crude Oil and
Natural Gas.
13.1. Regulations for Access Code
The Regulations for Access Code was passed in June 2007 by PNGRB for Natural Gas
transmission Pipeline and City or Local Natural Gas Distribution Network. The main objectives
of this access code are –
1.) Promote the development of a competitive gas market by establishing uniform principles for
owners and users of gas pipelines to allow transport and non-discriminatory access to the gas
pipelines and CGD Network.
2.) Prevent abuse of Monopoly Power
3.) Ensure that a Pipeline/CGD Owner provides minimum service of access to available capacity
on a “Firm Service” basis and/or on “Interruptible Service” basis.
4.) Provide basis for resolution of disputes.
13.2. Regulations for Exclusivity
Market Exclusivity
The entity winning the right to set-up CGD Network in a city will have 5 year marketing
exclusivity. After 5 years, the network will be thrown open to competition but a fresh entrant will
not be allowed to lay a new pipeline. It will have to use the network for which it will have to pay
a fee to the CGD Company.
However, a company that has operated a CGD Company for 3 years or more prior to the
appointment of PNGRB, i.e. 1st October, 2007 will have a marketing exclusivity for 3 years
compared to 5 years.
67
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Infrastructure Exclusivity
The CGD Company will have a lifetime exclusivity of 25 years for the pipeline network.
Eligibility Criteria
Those who want to obtain rights to set up a CGD network would need to meet the following
eligibility criteria:
 Body Corporate or Company registered under the Companies Act.
 Should have a credible plan for sourcing of Natural Gas.
 Should have experience of laying aggregate of over 300 Km of oil and gas pipelines or
form a Joint Venture with a company which has that experience.
 The entity should have experience of at least one year in operation and maintenance of a
CGD Network or should have a Joint Venture with 11% holding with another entity
having such experience.
 Appropriate technical assistant agreement for at least one year with another party having
experience of operating and maintenance of CGD Network for at least a period of one
year.
An entity interested in developing a particularly City gas project needs to submit “Expression of
Interest” to PNGRB with Rs 8-12 Lakh as fee depending upon population of the city (NonRefundable), Geographical Area, market potential of CNG and PNG, business plan.
68
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
Chapter 14 – Challenges for Implementation of City Gas
Projects
 Need of creating vast CGD network with accelerated pace, commensurate to wide public
Demand.
 Developing CGD specific safety standards and developing & multiplying their
monitoring by the third party
 Developing & multiplying core competence of skilled manpower to handle the operations
in cities after cities.
 Meeting public expectations –
I.
II.
III.
Cheaper fuel / competitive prices by multi operators.
Easy availability anywhere
Foolproof safety everywhere
 Expectations are to be met by the Government, by Regulator & by CGD operators.
Proper understanding of regulatory act & mechanism to avoid contradictions for synergy.
i. Logical clarity in the regulations to manage contradictions for win-win
situation.
ii. Common understanding of the act to be read as a whole to make it
effective & workable for the public good.
iii. Too much control not to dampen the spirit of free competition.
Regulatory systems to have:
i. Gas availability / allocation to all CGD entities, which are not gas
producer or marketer.
ii. Gas purchase pricing for CGD at affordable price for public good.
69
City Gas Distribution by Sarthak Kishore| GSPC GAS
CITY GAS DISTRIBUTION
iii. Single window clearance from various statutory bodies.
 Sharing of resources like equipment, inventories at reasonable prices.
70
City Gas Distribution by Sarthak Kishore| GSPC GAS