GSPC Gas Company Limited December, 2009 Gandhinagar Basic Concepts of Design & Construction of Gas Distribution Network

GSPC Gas Company LimitedDecember, 2009

Gandhinagar

Basic Concepts of Design & Construction of

Gas Distribution Network

City Gas Distribution – An Overview

WHAT IS CITY GAS DISTRIBUTION?

CGD is the last component of the Natural Gas value chain delivering Natural Gas to end users in town and cities to meet the demand for a cleaner, more efficient, economical and environmentally-friendly energy source.

CITY GAS DISTRIBUTION CONCEPTDevelopment of Pipeline Network in a pre-

defined geographical spreadMaintaining Different Levels of Gas

Pressure to meet the Demand of various segments of gas users - Domestic, Commercial, Industrial and Automobiles.

Designing high pressure and medium pressure network such that supply to any consumer is possible from either side.

Design gas storage / Gas sourcing for maximum survival period

Consider Health, Safety & Environment at all stages

Steps in the design of Gas Distribution System• Market demand estimated based on comprehensive

field survey of units covering domestic, commercial, industrial and transport sectors.

• Demand forecast projection is carried out for 20-25 years.

• Peak hour consumption estimated for network design.

• The system is to be designed based on 20-25th year projected demand at peak load in a phased manner.

• Reconnaissance Route Survey within the town to identify suitable routes for laying pipelines, locations for City Gate Station, District Regulating Station & CNG Station

• Network design and optimization with available software

• Design of Mother Station and Daughter / Daughter booster station for CNG supply to automobiles

• National / International standards adopted for design.

• Project implementation done subsequently.

Steps in the design of Gas Distribution System

Battery Limits

Distribution Zone

Transmission Distribution

City Gate StationTra

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HP Network

MPB Network

CITY GATE

Domestic and Commercial Users

DRS DRSDRS

MPA Network

CNG Mother Stations

LP Network

CGD SYSTEM BASIC CONCEPT

CGD PRESSURE REGIMESSr. No. Network Component Inlet from Inlet Pressure

Outlet Pressure

Outlet to

1 CGS Transmission line 99 - 60 barg 26 barg Steel Grid

2 Steel pipeline CGS 26 barg 26 – 14 barg DRS / CNG

3 DRS Steel pipeline 26 – 14 barg 4 – 1 barg MP MDPE pipeline

4 Service Regulators (SR) MP MDPE Pipeline 4 – 1 Barg 110 mBarg LP MDPE Pipeline

5 MP MDPE pipeline DRS 4 barg 4 – 1 bargIndustrial MRS &

Commercial Connections

6 LP MDPE Pipeline SR 110 mBarg 110 – 50 mBargRegulator of Domestic /

Commercial Connections

7 Industrial MRSMP MDPE pipeline

Steel pipeline

4 – 1.5 barg

26 – 14 barg

1.5 barg or customer specific pressure within the supply range

Industrial internal pipeline

8Online / Mother CNG Station

Steel Pipeline 26 - 14 barg 250 Barg Vehicle at 200 Barg

9 Domestic Connections LP MDPE Pipeline 110 – 50 mBarg 21 mBarg Meter & Gas Stove

10 Commercial ConnectionsLP MDPE Pipeline

MP MDPE Pipeline

110 – 75 mBarg

4 – 1 Barg

75 mBarg or customer specific pressure within the supply range

Meter & Gas Stove

City Gas Distribution – Applicable Codes &

Standards

European Standard

S. No. STANDARD NO. DESCRIPTION

1 EN 12186Gas supply systems - Gas Pressure Regulating Stations for Transmission and Distribution. Functional Requirements

2 EN 12279 Gas pressure regulating - installations on service lines

3 EN 1776Gas supply systems - Natural gas measuring stations - Functional requirements

4 EN 1594Gas supply systems- Pipeline for maximum operating pressure over 16 bar- Functional requirements

AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME)


1 ASME B16.11 Forged Steel Fittings, Socket-Welding and Threaded

2 ASME B31.3 Process Piping

3 ASME B31.8 Gas Transmission and Distribution Piping Systems

4 ASME B16.5 Pipe line flanges and flanged fittings

5 ASME B16.9 Factory - Made Wrought Steel Butt welding Fittings

6ASME- Boiler and Pressure Vessel Code

Section- IX- Qualification Standard for Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators

7ASME Boiler and Pressure Vessel Code- II

Part C- Specifications for welding Rods, Electrodes, and Filler Metals

8 ASME Boiler & Pressure Vessel Code Section - V, Non-destructive Examination

9ASME Boiler and Pressure Vessel Code

Section-II Materials Part A- Ferrous Material Specifications -

BS/DIN/ISO AND OTHER STANDARDS


1 ISO- 15590-1International Standard for Petroleum and natural gas industries - Induction bends, fittings and flanges for pipeline transportation systems

3 BS 6755: Part 2 Testing of Valves

4 DIN 30672, Part ICoatings of corrosion protection tapes and heat-shrinking products for pipelines for operational temperatures upto 50oC

6 DIN 30670 Polyethylene coatings for steel pipes and fittings

OIL INDUSTRY SAFETY DIRECTORATE (OISD STANDARDS)


1 OISD-226 Natural Gas Transmission Pipelines & City Gas Distribution Networks

2 OISD-GDN-115 Guidelines on Fire Fighting, Equipment and Appliances in Petroleum Industry

3Fire Protection Manual- TAC

Fire Engines, Trailer Pumps and Hydrant Systems

4 OISD- Standard- 141 Design and Construction requirements for cross country hydrocarbon pipelines

5 OISD-Std-118 Layouts for Oil and Gas Installations

AMERICAN PETROLEUM INSTITUTE (API)


1 API Standard 1104 Welding of Pipelines and Related Facilities

4 API Specification 5L Specification for Line pipe

5 API Spec. 6D Specification for Pipeline Valves ( Gate, Plug, Ball and Check Valves)

7 API Standard 1102 Specification for steel pipeline crossing & highways.

AMERICAN GAS ASSOCIATION (AGA)


1 AGA Purging Principles and Practices

2 IGE/TD/1 Steel Pipelines for High Pressure Gas Transmission

5 AGA: Report No. 7 Measurement of Gas by Turbine Meters

6 AGA Report No.3 Orifice metering of Natural Gas and other related Hydrocarbon fluids

7 AGA-Report No 8Compressibility factors of Natural Gas and other related Hydrocarbon gases

City Gas Distribution – System Components

CGD - InfrastructureMajor Constituents of CGD are;City Gate stationPipeline Network

Steel PipelinesPoly Ethylene PipelinesGI / Cu Pipes

Regulating StationsDistrict Regulating StationsService RegulatorsDomestic / Commercial / Industrial

RegulatorsMetering Stations / Metering &

Regulating StationsCNG Stations

CITY GATE STATION (CGS)

CGS is the location of Custody Transfer from Transmission Company to Distribution Company.

CITY GATE STATION (CGS) Inlet & Outlet isolation valves Knock Out Drum (KOD), If required Filter Metering Unit (Turbine / Orifice / Ultrasonic) Gas Chromatograph (GC), If required Pre-heater (if required) Pressure reduction skid comprising

Active & monitor RegulatorsStream discrimination arrangementSlam shut valve for over & under pressure

protectionCreep relief valves.

Odorising Unit

STEEL PIPELINE

The Steel Grid pipeline sizes is 12”NB & 8”NB whereas, spur lines shall be of 6”NB & 4”NB.

Steel pipelines used in the distribution system is fully coated. The coating is extruded polyethylene, with each weld joint coated with either heat shrink sleeves or field applied tape.

Prior to the pipeline being put into service, the distribution pipeline to be non-destructively tested by two methods. Firstly, welds would be radio graphed and, secondly, the completed pipeline extension would be hydro-statically tested at a higher pressure than its operating pressure.

After hydrostatic testing, the pipeline to be dried, purged and filled with natural gas. The testing and commissioning procedures will be detailed during the detailed design phase of the project.

STEEL PIPELINE

To protect the pipeline from corrosion, a cathodic protection (CP) system of impressed current is proposed. During the detailed design phase, the CP capability of the existing transmission system will be investigated to establish if it has the capacity to provide CP to the extension. If it is found that the existing system does not have the capacity, additional CP facilities will be designed.

The steel grid is installed at a minimum depth of 1.0 meter cover, and in accordance with Indian requirements.

MDPE PIPELINE

The distribution pipe is with Standard Dimension Ratio (SDR 9) for 20 mm, (SDR) 11 from 32 mm up to 63 mm & (SDR) 17.6 for above 63 mm. The term SDR is defined as the normal outside diameter (DN) divided by the minimum wall thickness.

It is standard practice in India to have a minimum 1.0 meter cover. This additional depth in a densely populated area would be recommended.

All MDPE pipe back filled with sand around it to protect the plastic material.

MDPE PIPELINE

Medium Density PolyEthylene (MDPE) Pipes

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 Pressure Class: SDR 9 (dia 20 mm), SDR 11 (dia 32 & 63 mm)

and SDR 17.6 (dia 90, 110, 125 and 160 mm). Operating pressure: 4 bar (g). Operating temperature range: - 10 0 C to + 40 0 C.

Advantages of PE pipes

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 Low heat conductivity (small thermal loss) Smooth surfaces (low pressure losses due to low

pipe friction) Easy to transport, handle and lay Longer life


Easier and speedier joining techniques to ensure leak tight joints by employing electro fusion techniques

Higher productivity, i.e., reduction in installation time (15 minutes in case of PE against 4 hours in case of steel), thereby lesser inconvenience to public

Reduced number of joints, hence safer and leak free system

Less time is consumed to repair PE damages as compared to steel damages

Good squeeze off properties

Longer design life of PE pipes (50 years) as compared to steel pipeline (30 years)

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


MDPE Fittings

Tech Spec: ISO 8085-3 or EN 1555-3

Material Grade: PE 100Terminal pin size: 4 or 4.7

mmVoltage: 39 – 40 Volts.Color: Black.

PE Stop Off Valves (Typical)

Standard: ASME B 16.40, EN 1555-4 Pressure Class: SDR 11. Design Pressure: 5.5 bar (g). Design Temperature: 45 0 C. Operating Temperature: 10 0 C to 45 0 C End Connections: PE Material (Spigot

Type) Stem Extension: Integral stem extension

required (Minimum 690 mm from the Top of Pipe)

Valve Design: One piece construction. Ball position Indicator: Open / Close limits

required.

Crimping Fitting (Typical specification)

Used to connect u/g PE pipes with a/g GI pipes Operating Pressure: up to 4 bar (g) Operating Temperature: 40 0 C Hydrostatic Test Pressure: Minimum hold Pressure

of 10 bar (g), for 1 hour duration Pneumatic Test Pressure: Minimum pressure of 6

bar (g), for 1 hour duration Pull out Test:

• Shall not fracture within the jointed assembly• Shall withstand the Pneumatic pressure leak test• Shall not leak

District Regulating Stations

District Regulating Station

District Regulating Station

Service Regulators

Typical requirements of Pressure Regulators used for domestic and small I&C customers

Maximum Inlet Pressure: Maximum 4 bar (g) Nominal Outlet Pressure: 100 mbar (g) Flow capacities: 50, 150, 200, 250 scmh End connections: Threaded (& Tapered) as per BS 21 Operating ambient temperature: up to 45 0C Lockup: Maximum pressure, under no-flow condition, up to

125 mbar (g) Creep relief valve: To protect against downstream over

pressure at low flows or in the event of valve seat malfunction, preset to 140 mbar (g)

Over Pressure Shut Off (OPSO): Device to protect against downstream over pressure, preset to 160 mbar (g)

Under Pressure Shut Off (UPSO): Device to protect against downstream under pressure with a pressure setting range 40 mbar (g) to 65 mbar (g)

Regulator Selection

Information required to select a regulator:

Maximum and Minimum inlet pressure Required outlet pressure Maximum flow rate Tolerance on outlet pressure Size of pipework Type of gas Safety features required Size of orifice OPSS, UPSS & Relief settings Installation indoors of outdoors Orientation of regulator

Gas MetersThe most common types of meters used are:

DiaphragmRotary 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: ¾”, 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


Advantages Disadvantages

Good flow turndown Filtration essential (50 microns or finer)

Tolerance to installation effects and load behaviour

Requires lubrication

Accuracy ±1% Physical size at large capacities

Much smaller than a diaphragm meter

Can create pressure fluctuations on on/off loads

Very long life Can cut off gas supply when it fails

Expensive


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 BargOutlet pressure – As required by customer

Industrial Metering Station (IMS)

MRS components

Inlet & Outlet isolation valves

FilterPressure regulator

with a built in slam – shut device

Relief valveStrainerFlow Meter (RPD,

Turbine, etc.)

GI ERW Pipes

Tech Spec: IS 1239 (Part 1) Types used: Medium Class and Heavy Class Material: IS 1387 Pipes shall be screwed with Taper threads Threads: Tapered and conforming to BS 21 Galvanizing: IS 4736

• Coating requirements: Mass of coating is 400 gms / m2

Test Pressure: 5 MPa Powder Coating:

• Powder Material: Pure Polyester• Application: Electrostatic spraying (40 – 90 KV,

Manual / Automatic)

GI Fittings (Malleable Cast Iron)

Tech Spec: IS 1879 Material: IS 2108 Grade BM 290 Dimensions: IS 1879 Threads: IS 554

• All Internal & External Threads shall be tapered

• Chamfer shall have included angle of 900 +/- 50 for Internal threads & 700 +/- 100 for external threads

Galvanizing: IS 4759• Coating requirements: Mass of coating is

700 gms / m2.

Forged Fittings (Wrought Steel Iron)

Tech Spec: IS 1239 Part 2 Material: IS 1387 Dimensions & Tolerances: IS 1239 Part 2 Threads: IS 554

• All Internal & External Threads shall be tapered• Chamfer shall have included angle of 900 +/- 50 for

Internal threads & 700 +/- 100 for external threads Galvanizing: IS 4759

• Coating requirements: Mass of coating is 700 gms / m2.

Brass Valves(Meter Control Valves, Riser Isolation Valves & Appliance Valves)

Tech Spec: EN 331 Pipe Nominal Diameter :- ¼” to 2” NB. Operating Pressure: 4 bar (g). Operating Temperature: 10 – 60 0 C. Material: Nickel Plated Forged Brass. Pattern: Full Bore, Quarter Turn Ball

Valve. Handle: Suitable Metallic Handle,

Lever / Knob / Cap Type with yellow coating (Powder / Plastic) on Surface marked as “GAS”

End connection: Screwed, As per BS EN 10226-1, Tapered Threaded, Female

Meter Regulator Gas flow rate: 2.5 m3/h Nominal Inlet Pressure: 100 mbar (g) Maximum Inlet Pressure: 160 mbar (g) Nominal Outlet pressure: 21 mbar (g) Lock-up pressure: Shall not exceed 30 mbar (g) Low pressure Cut-Off: at inlet pressure of 11.5 mbar to 15

mbar (g).• Re-pressurization safety device is fitted which prevents the

regulator from re-opening when the inlet pressure is restored unless there is a downstream backpressure, i.e., all connected appliances have been turned off.

End connections: Right angled inlet and outlet connections of ¾”x ¾” BSPT (Female)

Rubber Hose (flexible and steel wire braided)

Used to connect the appliance, inside the house of domestic customer

Tech Spec: Type IV of IS 9573 Size: 8 mm NB Material: It consists of

A. Lining: Synthetic rubber like Nitrile Butadiene Rubber (NBR) or Chloroprene Rubber (CR)

B. Reinforcement: Wire reinforced in braided form in between the lining and the cover

C. Cover: Consolidated by wrapping, and uniformly vulcanized to give good adhesion

Mechanical Properties:• Tensile strength: Minimum 10 MPa for lining and cover• Elongation at break: Minimum 200% for lining and 250%

for cover Salient features:

• Strong (Steel wire reinforced) hence rats can't bite through steel wire Flame resistant

• Abrasion, ozone and weather resistant, hence no cracks• Low temperature flexibility• Minimum burst pressure of 0.5 MPa• Long life (5 years)• Grip strength (to nozzle of appliance)

Rubber Hose (flexible and steel wire braided)

City Gas Distribution – Network Design

System BasicsSystem of units

The International System of Units (SI), also known as the "Metric System" to be used. The International Gas Union (IGU) has also recommended to generalize the use of the SI system in all matters relating to Gas and Gas facilities. The SI system shall be in compliance with ISO 1 000. The SI system shall be of general use with exception to the following: Gas Volumes and Flow, Pressure, Temperature, Heating Value

Pipeline and Piping Nominal Diameters shall be expressed under either one or both systems where "Common Practice" of Pipeline and Piping Engineers so suggests;

System BasicsData relating to equipment shall use that

system of unit that is most common in the relations with suppliers.

Where advisable for good understanding, the corresponding value in the other System of Units shall be mentioned between brackets.

Results of technical calculation and related figures issued from specific software shall remain expressed in that system of units that is used by the relevant software.

Steel PipelinesSteel mains

Notwithstanding the major advantages of polyethylene (PE), steel pipelines remain necessary as follows;

High-Pressure MainsLocation class: the design of High pressure mains

shall consider requirements as for Location Class 4 (ASME 31.8) to allow timelessness should the environment change in the future.

Wall thickness: according to ASME B31.8 – Section 841.11 with Design factor of 0.4. In addition, wall thickness shall, in no way, be lower than the values below in function of Nominal Diameter (ND)

Steel Pipelines 4 in. and below - 3.9 mm 6 in. - 4.5 mm 8 in. - 5.0 mm 10 in. - 5.6 mm 20 in. - 6.3 mmGSPC Gas is using 6.4 MM Wall thickness. Steel Grade: The Design Concept considers

API Grade X 52 Steel quality to offer maximum flexibility for line pipes procurement.

Bend Radius: to allow pigging under special circumstances

Steel PipelinesSteel Pipes API 5 L - Line Pipes ASTM A 106 - Seamless Pipes ASTM A 333 - Seamless & Welded Pipes for low

temperature services

Location Class Location Class I - 10 or fewer buildings in 1 mile section Location Class I I - 10 – 46 buildings in 1 mile section Location Class III - 46 or more buildings in 1 mile section Location Class IV - Areas where multi story building &

heavy traffic plus other underground utilities

Steel Pipe Design FormulaeP = (2 St/D) * FET – As per ASME B 31.8, 841.11 (a)

t = PD / 20fs

Steel PipelinesAbove Ground MainsPolyethylene 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 PipelinesProcess DesignWey-mouth Formulae

Q = 0.0813 * (d)2.6667 * {(p12-p22)1/2 / (S * L)1/2 }

Velocity V = Q / AVelocity for filtered gas to be 40 m/s

& unfiltered gas to be 20 m/s maximum.

Example

1 2

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 * v0.2497 = (3.14/4) * (200.1 * 10-3)2 * vV = 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

Example

1 2 3

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 coefficientThe 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 PipelinesBase 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 thicknessThe 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

Different Material used for PE PipesThe following materials have been approved to

date:Solvay Eltex TUB 121(Black) or Eltex TUB 125(Orange) PE

100 Borealis HE 2490 PE 100Fina Finathene XS 10 B PE 100Dow BG 10050 PE 100Elenac 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 DesignWey-mouth Formulae

Q = 0.11672 * (d)2.664 * {(p12-p22)0.544 / (S * L)1/2}Velocity

V = Q / AVelocity 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.

Polyethylene Pipelines

Process DesignPolyflow Formulae

Q = 1.522786 * 10-3 * (d)2.623 * {(h/L)0.541}Peak Gas flow is assumed @ 0.5 SCMH

for one houseBeing a standard PNG Connection, we

have standardize the design of PNG Network as follows;½” 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.


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 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.


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. The Teflon 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

Documents

GSPC Gas Company Limited December, 2009 Gandhinagar Basic Concepts of Design & Construction of Gas Distribution Network