Basic Concepts of Design & Construction of Gas Distribution Network
Basic Concepts of Design & Construction of Gas Distribution Network
Basic Concepts of Design & Construction of Gas Distribution Network
Distribution Zone
HP Network
CITY GATE
MPB Network
MPA Network
4 Service Regulators (SR) MP MDPE Pipeline 4 1 Barg 110 mBarg LP MDPE Pipeline
Industrial MRS &
5 MP MDPE pipeline DRS 4 barg 4 1 barg Commercial
Connections
Regulator of Domestic /
6 LP MDPE Pipeline SR 110 mBarg 110 50 mBarg Commercial
Connections
1.5 barg or
MP MDPE pipeline 4 1.5 barg customer specific Industrial internal
7 Industrial MRS
Steel pipeline 26 14 barg pressure within pipeline
the supply range
Online / Mother CNG
8 Steel Pipeline 26 - 14 barg 250 Barg Vehicle at 200 Barg
Station
9 Domestic Connections LP MDPE Pipeline 110 50 mBarg 21 mBarg Meter & Gas Stove
75 mBarg or
LP MDPE Pipeline 110 75 mBarg customer specific
10 Commercial Connections Meter & Gas Stove
MP MDPE Pipeline 4 1 Barg pressure within
the supply range
City Gas Distribution
Applicable Codes & Standards
European Standard
S. No. STANDARD NO. DESCRIPTION
ASME Boiler and Pressure Vessel Part C- Specifications for welding Rods, Electrodes, and Filler
7
Code- II Metals
1 OISD-226 Natural Gas Transmission Pipelines & City Gas Distribution Networks
4 OISD- Standard- 141 Design and Construction requirements for cross country hydrocarbon pipelines
7 API Standard 1102 Specification for steel pipeline crossing & highways.
AMERICAN GAS ASSOCIATION (AGA)
6 AGA Report No.3 Orifice metering of Natural Gas and other related Hydrocarbon fluids
Diaphragm
Rotary Positive Displacement (RPD)
Turbine
Diaphragm Gas Meters (Domestic)
Tech Spec: EN 1359
Capacity: 2.5 m3/hr
Rangeability or TD ratio: 1:150 or better
Nominal Working Pressure: 21 mbar (g)
End Connections: , as per BS 746 (Male)
Center to Center distance: 110 mm between inlet
and outlet connections
Diaphragm Gas Meters (Commercial)
Tech Spec: EN 1359
Capacity: 10, 25, 40, 65 scmh
Rangeability or Turn Down ratio (ratio
of Qmax and Qmin): 1:150 or better
Nominal working Pressure: 100 mbar
(g)
Pressure rating : Suitable to withstand
maximum working pressure of 200 mbar
(g)
Rotary Positive Displacement (RPD) meters
Tech Spec: EN 12480
Volumetric meter
Appropriate for medium size load
Typical Turndown 35:1 to 50:1
Accuracy 1%
Large measuring range
Not sensitive against disturbances
Not sensitive against fast changes in
flow rate
Needs lubrication
Rotary Positive Displacement (RPD) meters
Rotary Positive Displacement (RPD) meters
Advantages Disadvantages
Expensive
Industrial Metering Station (IMS)
IMS are used to measure gas supplied to Industrial consumers
Main component in IMS is filter, Isolation Valves, RPD Meters
with EVC & Modem, Regulators (If low pressure requirement)
and Non return Valve
Inlet pressure range 1.5 Barg to 4 Barg
Outlet pressure As required by customer
MRS components
Inlet & Outlet isolation
valves
Filter
Pressure regulator with a
built in slam shut device
Relief valve
Strainer
Flow Meter (RPD, Turbine,
etc.)
GI ERW Pipes
t = PD / 20fs
Steel Pipelines
Above Ground Mains
Polyethylene being forbidden for above ground crossings, if any,
steel mains sections are needed at the crossing with PE/steel
transition fitting to be buried with the adjacent PE mains.
Steel Pipelines
Process Design
Wey-mouth Formulae
Q = 0.0813 * (d)2.6667 * {(p12-p22)1/2 / (S * L)1/2 }
Velocity
V = Q /A
Velocity for filtered gas to be 40 m/s & unfiltered
gas to be 20 m/s maximum.
Example
P 1 = 15 Barg, P2 = 10 Barg (Min.)
Q = 2,00,000 SCMD
1 2
L = 32,000 m
Example
Q = 2,00,000 SCMD i.e. 9,166.66 SCMH
Using Wey Mouth Formulae: Q = 0.0813 * (d)2.6667 * {(p12-p22)1/2 / (S * L)1/2}
9166.66 = 0.0816 x (d)2.6667 * {(16.0132-10.0132)1/2/(S* L)1/2}
d = 198.52 mm : Calculated Diameter.
We have to select diameter from the available range e.g. 200.1 mm from API 5 L
Now, P1V1 = P2V2
1.013 * 9,166.66 = (9.32+1.013) * V2
V2 = 898.8 M3 / Hr = 0.2497 M3 / Sec.
Now, for Velocity, Q = A * v
0.2497 = (3.14/4) * (200.1 * 10-3)2 * v
V = 7.94 m/s
Now, for Wall Thickness, t = (P*D) / 20fs
t= (16.013 * 219.1) / (20 * 0.29 * 241)
t = 2.5099 mm
Example
P 1 = 26 Barg, P2 = 10 Barg (Min.)
o Q=1 Q = 9250
1 2 3
o L = 12000 m L = 20000
Q = 4000
L = 7000
21
Polyethylene Pipelines
MRS (Minimum Required Strength)
The MRS value represents the long-term circumferential stress in the pipe
under which the break may occur after 50 years at the earliest.
Stress = MRS / C, where C is overall service coefficient
The minimum value of C for the material to be used for Gas application is 2.
MAOP (Max. allowable Operating Pressure)
MAOP = (20 * MRS) / [C * (SDR-1)].
Standard Dimension Ratio
SDR = Dn / En
SDR used in GSPC Gas is SDR 9, SDR 11 & SDR 17.6
Standard followed by GSPC Gas
IS 14885: 2001
Polyethylene Pipelines
Base resin
The PE resins of Third Generation (PE 100 or MRS 10) in full
compliance with detailed specification is being used. First
Generation is PE 63, second PE 80 & Third generation is PE
100.
Wall thickness
The MDPE network designed and qualified for a MOP of 4 bar.
The Network analysis and resulting structure and behaviors
are based on such design. PE line pipes wall thickness shall be in
accordance with the following SDR
Gas mains (ND 90 mm): SDR 17.6
Gas mains and Service lines (ND 90 mm): SDR 11.
Service lines (ND = 20 mm): SDR 9
Polyethylene Pipelines
Different Material used for PE Pipes
The following materials have been approved to date:
Solvay Eltex TUB 121(Black) or Eltex TUB 125(Orange) PE 100
Borealis HE 2490 PE 100
Fina Finathene XS 10 B PE 100
Dow BG 10050 PE 100
Elenac Hostalen CRP 100 PE 100
Codes:
Manufacturer Commercial Brand Name Code(*)
SOLVAY ELTEX TUB 121/125 E3
BOREALIS HE 2490 N3
FINA FINATHENE XS 10 B F3
DOW BG 10050 D3
ELENAC HOSTALEN CRP 100 H7
Polyethylene Pipelines
Process Design
Wey-mouth Formulae
Q = 0.11672 * (d)2.664 * {(p12-p22)0.544 / (S * L)1/2}
Velocity
V = Q /A
Velocity for filtered gas to be 40 m/s & unfiltered gas
to be 20 m/s.
Being a complex network, required specialized tools for
Planning & Designing the network. GSPC Gas use
SynerGEE software for designing the PE Network.
PNG Domestic & Commercial
Connection
Process Design
Polyflow Formulae
Q = 1.522786 * 10-3 * (d)2.623 * {(h/L)0.541}
Peak Gas flow is assumed @ 0.5 SCMH for one house
Being a standard PNG Connection, we have standardize
the design of PNG Network as follows;
GI pipes up to G + 4 apartments OR 5 connections in case of raw house.
1 GI Pipe above 5th Floor apartment OR above five connections in raw
house.
PNG Domestic & Commercial
Connection
Route Selection for GI / Copper Pipe Installation
Route selection for GI pipe installation shall be carried out as per the guideline
given below;
Pipe shall not be installed on un-plastered wall or in the house under construction.
Pipe shall not be installed 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 shall be away (minimum distance of 200mm) from the electrical
line.
There shall be minimum change of directions and minimum no of threaded joints.
Maximum two Point in the kitchen for gas stove only.
Compound gate or doors and windows inside the house shall not hit the Gas pipeline.
Copper installation should be a minimum 300mm away from heat source and
Electrical installations. If it is not possible for copper installation then suitable
protection should be given.
If the copper pipe installation is carried out inside cupboards, there should be a
provision for adequate ventilation like louvers/holes in cupboard doors.
PNG Domestic & Commercial
Connection
Positioning of Valves, Regulator & Meter
Riser IsolationValve:
For apartments, one riser isolation valve shall be provided at a height of 2 meter
From the ground and individual meter control valve shall be installed for each
connection.
The riser isolation valve shall be installed at a convenient height so that it is easy to
operate the valve in emergency.
Meter Regulator:
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.
PNG Domestic & Commercial
Connection
Gas Meter:
Gas Meter shall be installed 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.
Meter shall be installed at convenient height so that it is easy for the meter
reader to take correct readings.
The meter shall never be positioned very near to Electric Line. A minimum
distance of 200 mm shall be maintained.
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.
Clamping
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.
If the length of pipes is not correct, the threaded joints come under heavy
stresses, which may ultimately cause gas leakage.
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.
The condition of thread die and pipe vice jaws shall be checked regularly and
shall be free from defects.
Cutting fluids (oils) shall be used while thread cutting.
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.
G.I. Pipe Installation & Clamping
Teflon tapes shall be wrapped on threaded portion of the pipe with minimum
three overlaps.TheTeflon tap should be of approved make and gauge.
The no of clamps shall be adequate. 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.
Distance between two clamps shall not be more than 2 meter; the gap between
riser and wall shall be minimum 25 mm.
Clamps shall be installed in a straight line and shall be parallel to each other.
The clamps shall be fixed properly on the walls and should grip pipe in position.
For wall crossing, drill the hole with the help of electrical drilling machine in
such a way that plaster and tiles shall not be damaged. It shall be ensured that
there is no concealed wiring or any other fitting on the opposite side of the wall
for a particular location of drilling.
G.I. Pipe Installation & Clamping
Self-adhesive anticorrosive tape shall be wrapped on the pipe with 50% overlap.
Casing sleeve shall be installed in wall for wall crossing.
Alignment of the pipeline shall be maintained.
Whenever compound gate, house door or window 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.
Wherever powder coating is peeled off during fitting and tightening of the pipe,
touch up shall be done after the installation is completed by two coats of
approved paint.
Prior to installation all pipes and fittings shall be checked internally to ensure
that they are free from any obstruction.
PE to GI (transition fitting) joint shall be provided above ground.
Installation of Valves, Regulator &
Meter
Union and testing T shall be installed before riser isolation valve.
Meter control valves, Meter regulator and Gas meter shall be
protected from the over tightening of the thread.
Valves, Meter regulator and Gas meter shall be installed with the
clamps on both sides. As far as possible hex nipple shall not be
used for connecting. Both side threaded 3 to 8 long pipe nipple
shall be used.
Gas meter, regulator and installed piping shall be aligned properly.
Flow direction of the gas meter shall be checked before
installation.
Flat rubber washer shall be checked and ensure at inlet and out let
of the adaptor joint to the meter.
Pipe nipple shall be installed between elbow and regulator to avoid
direct load of line or riser on regulator and a clamp must be
provided on the pipe nipple.
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. Pneumatic
testing pressure shall be kept 1.5 times of the working pressure and should be
maintained for 30 minutes.
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.
Conversion of Burner
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 rubber hose.
The length of rubber hose shall not exceed 1.5 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.
All the Best