Jerin Project

1PROJECT REPORT CITY GAS DISTRIBUTION PROJECT IN DEWAS COMPLETED AT GAIL GAS LTD. DEWAS, MADHYA PRADESH Submitted by JERIN JOSE B.Tech APE with GAS Specialization UNIVERSITY OF PETROLEUM AND ENERGY STUDIES 2 DECLARATION I hereby declare that the project entitled “City Gas Distribution Project in Dewas” submitted for the B.Tech Degree is my original work and the project has not formed the basis for the award of any degree, associateship, fellowship or any other similar titles. Signature of the Student: Place: Date: 3 CERTIFICATE This is to certify that the project entitled “City Gas Distribution Project in Dewas ” is the bonafide work carried out by Jerin Jose student of B.Tech APE with Gas Specialization University of Petroleum and Energy Studies, Dehradun, during the year 2012, in partial fulfillment of the requirements for the award of the Degree of Bachelor in Applied Petroleum Engineering and was completed in Gail Gas Lltd , Dewas,MP. The project has not formed the basis for the award previously of any degree, diploma, associateship, fellowship or any other similar title. Signature of the Mentor : P S Atal (Deputy Manager(CGM) Place: Dewas Date: Signature : B P Toppo(Chief Manager) Place: Dewas Date: I would also like to thank our Dean of College of Engineering Studies. Dr.4 ACKNOWLEDGEMENTS I am extremely thankful to Gail Gas Ltd. Tech (3rd year) APE with Gas specialization University of Petroleum and Energy Studies Dehradun . I tender my special thanks to Shri B P Toppo. I express my sincere thanks to Shri Sunil Charpe. who assisted me with his valuable knowledge and devoted his precious time to aid me in enhancing my technical skills and practical knowledge.Shri V K rathore who helped me complete the project. Shri P S Atal deputy manager(CGM). Shri S K Kar . I would like to express my sincere thanks my guide through the project. for providing me the opportunity to complete the project as a part of training. Shrihari for making available this opportunity. JERIN JOSE B.chief manager(CGM). Shri Lalavat for helping me in my endeavour to complete this project work. Shri shashi Ranjan. and ceramic-tile kilns. offering important environmental benefits when compared to other fossil fuels.use of efficient material for transportation which resists corrosion. and cooking stoves. This project shows the city gas distribution project carried out in the city dewas. it is used in brick. commercial and automobile sectors. Some of the problems associated with city gas distribution is the transportation of natural gas which includes operations in pipeline layout.. carbon black. The project includes various maps and diagrams of the pipeline layout in the city dewas. Pressure regulation using regulators and valves are very important in transportation and delivery of natural gas for various consumers including domestic. industrial or commercial premises and Compresses natural gas (CNG) stations for transportation purpose. As an industrial fuel. and the equipments used in city gas distribution. for generating steam in water boilers.This project so covers the city gas distribution project carried out by the operating company gail gas ltd. water heaters.5 ABSTRACT Natural gas is used primarily as a fuel and as a raw material in manufacturing.testing of materials used. . Other factors include health and safety . Its illustrates the above mentioned operations carried out here. It is used in home furnaces. and as a clean heat source for sterilizing instruments and processing foods. City natural gas distribution network means an interconnected network of gas pipelines and the related equipment used for transporting natural gas from a bulk supply high pressure transmission main to the medium pressure distribution network and subsequently to the service pipes supplying natural gas to domestic. cement. in glass making. sulphur.proper networking of pipeline in the city. mp by gail gas ltd. and ammonia. industrial . As a raw material in petrochemical manufacturing. Natural gas is considered as an environmentally friendly clean fuel. natural gas is used to produce hydrogen. . 8. Abstract ………………………………………….. 5...10-11 Gail Gas Overview …………………………….22-37 Laying of Pipeline Network………………….....18-19 Piped Natural Gas ……………………………20-21 City Gas Distribution System……………..12-13 Introduction ………………………………....14-17 Compressed Natural Gas . 16. 13. 10.59-69 Appendix………………………………………. 9. 12... 14... 7.....5 About Dewas ……………………………………... 11. 2.... 6.55-58 CNG Station…………………………………..... 3.…………………….6 CONTENTS Page no 1..38 -46 Pipeline Network in Dewas……………………47-50 Design of Steel pipe……………………………51-54 Design of Polyethylene pipe…………………..... 15. 4.70-72 Conclusion………………………………………72 References………………………………………73 .7-9 PNGRB ………………………………... Khandwa (formerly East Nimar) district to the south. TOPOGRAPHY: The geographical boundaries are Ujjain district to the north.06 Latitude. It is situated on the Malwa Plateau.82 sq. km which consists a total population of 231.672 with a sex ratio of 913 per 1000 Males. POPULATION: The district is divided into 45 wards covering a total area of 90. To cater the need for drinking water for the population main. on the west-central part of the state. Also. It is the administrative center of the Dewas District. Rivers flowing nearest to Dewas are Kshipra (12 km) and Lodhari (13 km). about 160 km south west from state capital.58˚ Latitude and 76. Dewas.140 population lives below poverty line. To the northeast is found the district of Shahjapur while Hoshangabad district is to the southeast. Lastly. Dewas is an industrial town. with companies like Ranbaxy and Tata International being prominent players. It is located at 22. to the southwest is Khargone. Bhopal.7 ABOUT DEWAS LOCATION: Dewas is a district of Madhya Pradesh. (Hindi: दे वास)is an ancient town situated on the Malwa plateau in the West-central part of Indian state of Madhya Pradesh. Today. Indore district to the west and Sehore district to the east. formerly West Nimar. a total of 145. sources with their capacities are: . Caparo tubes etc.Conventional resources are available like Wind and Bio-mass. of units 2001 Nil Nil 15 351 01 2002 Nil 01 13 383 Nil 2003 Nil Nil 18 402 Nil 2004 01 Nil 20 453 Nil 2005 01 Nil 25 488 Nil RESOURCES AVAILABLE: The development of a town can be ensured by utilizing the resources available to its fullest for Residential as well as Industrial sector.5 MW of power generation. automotive and railway gears.8 Well Tube well Tanks/ponds Hand pump Tap Water River/ canal Others Nil 2. Non. A table given below gives the number of units for various industries in different years: Sl. Tata International. .No 1 2 3 4 5 Type of Industries Large Medium Small House Hold Hazardous No.1 MLD Nil 8. Some of them are Ranbaxy Laboratories. VE Commercial.50 MLD 0. Together they have a potential of 253. LPG cylinders and polypropylene gas. INDUSTRIES: As for industries. the district is engaged in the manufacturing of textile chemicals.00 MLD Nil with a per capita consumption of 40 LPCD.70 MLD 1. among others. In Dewas. Hyline Glass works (P) Ltd. Barlocher Tirupati Balajee Krishna Foods Products. VE Commercial Dewas Techno Prayag Forge Agrophos Bagree Alloys Pithampur tools 13 14 15 16 17 18 19 20 21 22 23 24 MP BRK Energy Foods Caparo tubes STI Sanoh Adroit Industries Gabriel India Unicon Metal & Alloys Ltd. Industrial and Commercial sectors. nergy from both Renewable and Non-Renewable sources are used to fulfill the energy consumption requirement.Ltd. These Industries are: 1 2 3 4 5 6 7 8 9 10 11 12 Ranbaxy Laboratories Ltd. Currently. Natural Gas. Kuber Lighting Jajoo Surgicals Bhandari Foils & Tubes Ltd. cleaner and easy to handle fuel i. Tata International Ltd. Owing to the difficulty in the supply and availability of Energy resources for the Industrial purpose. Sharda Minerals Ltd.9 ENERGY CONSUMPTION: Since Dewas needs energy for Residential.5 MW from Bio-Mass & 107.41MMSCM of Natural Gas (Both PNG and CNG) and 3. currently there are 24 Industries which have switched base from Fuels like LPG. Bhandari Foils .e. Varun Fertilizers Pvt. Furnace Oil. Wood etc to more safer.2 MW from Wind Energy generated Electricity. Dewas is consuming 1. distribution. PNGRB aims at creating a vibrant energy market with rapid and orderly growth through facilitation of flow of investments into the basic infrastructure for efficient transportation and distribution of petroleum. petroleum products and natural gas and to promote competitive markets and for matters connected therewith or incidental thereto. B) Register entities to- . Welding. 2006 (NO.10 Petroleum and Natural Gas Regulatory Board (PNGRB) The Petroleum and Natural Gas Regulatory Board (PNGRB) was constituted under The Petroleum and Natural Gas Regulatory Board Act. 19 OF 2006) notified via Gazette Notification dated 31st March. Further as enshrined in the act. petroleum products and Natural Gas at minimum cost and high level of protection of consumer interests through fair trade practices and competition amongst the entities so as to enhance the competitiveness of Indian economy and customer satisfaction.. petroleum products and natural gas excluding production of crude oil and natural gas so as and to ensure uninterrupted and adequate supply of petroleum. storage. marketing and sale of petroleum. Installation and Testing. transportation. These include directions for Material and Equipments. The Act provide for the establishment of Petroleum and Natural Gas Regulatory Board to protect the interests of consumers and entities engaged in specified activities relating to petroleum. Piping System components and Fabrication details. Design. 2006. the board has also been mandated to regulate the refining. processing. Operating and Maintenance Procedure and Corrosion Control. It directs and provides safety measures for both City and Industrial Natural Gas Distribution System. petroleum products and natural gas in all parts of the country. Functions of Board: The Board shallA) Protect the interest of consumers by fostering fair trade and competition amongst the entities. (H) Maintain a data bank of information on activities relating to petroleum. petroleum products and natural gas1. ensure display of information about the maximum retail prices fixed by the entity for consumers at retail outlets. (G) Levy fees and other charges as determined by regulations. secure equitable distribution for petroleum and petroleum products. operate or expand a common carrier or contract carrier. 2. (I) Lay down. 2. petroleum products and natural gas. 2. provide. operate or expand city or local natural gas distribution network. by regulations. (D) Declare pipelines as common carrier or contract carrier. access to common carrier or contract carrier so as to ensure fair trade and competition amongst entities and for that purpose specify pipeline access code. 5. by regulations. lay. the technical standards and specifications including safety standards in activities relating to petroleum. monitor transportation rates and take corrective action to prevent restrictive trade practice by the entities.11 1. monitor prices and take corrective measures to prevent restrictive trade practice by the entities. 3. 3. 3. petroleum products and natural gas. (C) Authorise entities to1. (F) In respect of notified petroleum. market notified petroleum and petroleum products and. ensure adequate availability. 6. by regulations. establish and operate liquefied natural gas terminals. build. lay. access to city or local natural gas distribution network so as to ensure fair trade and competition amongst entities as per pipeline access code. petroleum products or natural gas exceeding such capacity as may be specified by regulations. including the construction and operation of pipeline and infrastructure projects related to downstream petroleum and natural gas sector. . and enforce. transportation rates for common carrier or contract carrier. 4. natural gas. retail service obligations for retail outlets and marketing service obligations for entities. establish storage facilities for petroleum. subject to the contractual obligations of the Central Government. build. (E) Regulate.1. 2. Natural gas trading.2008. interested entities may submit the bids and whoever is successful in the bidding . Laying of OFC/ Duct to leverage for potential business. It is India's principal gas transmission and marketing company.05. GAILTEL and Others.GAIL commissioned the 2. The company was previously known as Gas Authority of India Ltd. Allied business relating to distribution & marketing of natural gas. CNG.12 GAIL GAS – OVERVIEW GAIL GAS is a wholly owned subsidiary of GAIL (I) Ltd. It has six segments: Transmission services of natural gas and liquefied petroleum gas (LPG). When the bids are called for the CGD network development by the PNGRB. GAIL has further set up six more JVCs viz Bhagyanagar Gas Limited. LPG and Liquid hydrocarbons.800 km Hazira-Vijaipur-Jagdishpur (HVJ) pipeline in 1991. Maharashtra Natural Gas Limited in Pune Maharashtra and Tripura Natural Gas Company Limited in Tripura. The results of these ventures are quite visible through the improvement in air quality in these cities. GAIL began its city gas distribution in New Delhi in 1997 by setting up nine compressed natural gas (CNG) stations. Andhra Pradesh. Avantika Gas Limited in Madhya Pradesh. Investing in & setting up required infrastructure in various cities of India and along the highways for building CNG corridors. of CNG & Auto LPG as fuel for vehicles. GAIL took many initiatives to introduce PNG for households and CNG for the transport sector to address the rising pollution levels. Pilot projects were launched in early 1990s in two metros Delhi and Mumbai through joint venture companies Indraprastha Gas Limited (IGL) and Mahanagar Gas Limited (MGL) leading to the start of commercial operation of city gas projects. Auto LPG etc. three liquefied petroleum gas (LPG) plants were constructed and some regional pipelines acquired. petrochemicals. in India and abroad. Distribution and Marketing. It was set up by the Government of India in August 1984 to create gas sector infrastructure. GAIL (India) Limited is the largest state-owned natural gas processing and distribution company headquartered in New Delhi. for CGD projects in various cities. During 1991-93. India. Central U P Gas Limited & Green Gas Limited in Uttar Pradesh. Based on the success of IGL and MGL. PNG for domestic/ commercial/ industrial purposes. enabling GAIL to begin its gas transportation in various parts of India. was incorporated on 27. 80. This has induced other entities to come into CGD projects and thus a competitive era in this field has been initiated. Sonepat (Haryana). Meerut (Uttar Pradesh). In this competitive environment. Various cities are covered in the network.00. GAIL Gas Limited has been authorized by PNGRB and MoPNG for implementing City Gas Distribution Projects in Dewas (Madhya Pradesh).000 automobiles as Compressed Natural Gas (CNG) and over 7.13 will be authorized to develop the CGD network consisting of CNG & PNG infrastructure in that particular city. dedicated to CGD projects. This has necessitated the establishment of GAIL Gas Ltd. Kota (Rajasthan). Gas supplied by GAIL to retail gas distributors serves more than 6. energy and focus have been taken to maintain GAIL's leading position in CGD projects. . Firozabad (Uttar Pradesh) and Vadodara (Gujarat). a sincere and dedicated approach.000 households as Piped Natural Gas (PNG). • Biogenic gas is formed at shallow depths and low temperatures by the anaerobic bacterial decomposition of sedimentary organic matters. propane . It may be dry and wet . hydrogen sulphide etc. The action of chemical and micro-biological process on formerly living matter under condition of elevated temperature and pressure appear to result in natural gas as the ultimate degradation products. • Thermogenic gas is formed at deeper depth by thermal cracking of sedimentary organic matter into hydrocarbon liquid and gas. The presence of these components differs from source to source. It is the heaviest components that first condense when it reaches its “Dew point” temperature . Non associated gas can contain hydrocarbon gases such as carbon dioxide . butane & other heavier hydrocarbons . Retrograde Condensate: Natural gas typically contains many liquid hydrocarbon components with the heavier components found in smaller amounts than the lighter gaseous ends. thermogenic gas can also contains significant concentration of ethane.The temperatur e at which Hydrocarbon begin to condense in the gas stream is known as “Hydrocarbon dew point (HDP)” . The reservoirs of Non associated Gas that contains only gas but no oil. Wet non associated gas is in equilibrium with condensate in the reservoirs normally at higher pressure .14 INTRODUCTION Natural Gas is a gaseous fossil fuel that has methane as its primary component. Dead plants and animals get sedimented over a period of time in the porus sedimentary rocks. The varieties of gas compositions can be broadly categorised into i) ii) Non Associated gas Associated Gas Non Associated Gas is produced from geological formation that typically does not contain much higher hydrocarbon than Methane. The natural gas produced from geological formation comes in a wide array of composition . Wet non associated gas is in equilibrium with condensate in the reservoirs normally at higher pressure. Biogenic gas consists almost entirely of methane . It formed by the decomposition of organic compounds in the absence of oxygen under the earth. 6 degree C (-) 188 Degree C 5% to 15% in air 2148 Degree C 9880 Kcal B) Inorganic Substances: Nitrogen (N2) Carbon Dioxide (CO2) Sulphur Components (H2S & Other) Helium Mercury (0-25) % (0-5) % 4-50 ppm Traces Traces . (Gaseous) (-) 161. Natural Gas available from such sources is known as Associated Gas. burn with Blue Flame 0.15 Natural Gas is often found dissolved in oil at the high pressure existing in a reservoir and it may be present as a Gas Cap above the oils. An associated gas may contain more heavy fractions (Ethane & Higher Hydrocarbons) than non associated gas.717 kg/ m3. Properties of Natural Gas: Appearance Density &Phase Boiling Point Flash Points Explosive Limit Flame Temperature Gross Calorific Value Component of Natural gas A) Organic Substances: Methane (CH4) Ethane (C2H6) Propane (C3H8) Butane (C4H10) Pantene (C5H12) Hexane (C6 H14) Higher Hydrocarbons (82-96) % (4-10) % (2-6) % (2-4) % (0-1) % (0-1) % (0-1) % Clear. industrial and commercial customers in Mumbai in 1995. industrial or commercial premises and Compresses natural gas (CNG) stations for transportation purpose.16 City natural gas distribution network means an interconnected network of gas pipelines and the related equipment used for transporting natural gas from a bulk supply high pressure transmission main to the medium pressure distribution network and subsequently to the service pipes supplying natural gas to domestic. supply of gas commenced to industrial consumers around Mumbai like MSEB. CITY GAS DISTRIBUTION IN INDIA Oil India Limited (OIL) was first to start distribution of gas in Assam in the 60s. The two factors that will drive this growth are increase in gas production (from the KG basin) and the development of infrastructure. industrial and CNG for transportation. The focus of IGL was to provide CNG to the transport sector in view of Supreme Court judgment making CNG compulsory. the first cross country pipeline in India was conceptualized with Hazira as the landfall point in Gujarat. With the find of Oil / Gas at Mumbai high. Gas Authority of India (GAIL) was formed in 1984. It is assumed to increase to an amazing 20MMSCMD in the next four years. . The City gas distribution accounts for 4-6MMSCMD in the country. The City gas distribution in the India is increasing at a rapid rate for the usage of PNG for the domestic. Gujarat Gas Company Limited (GGCL) was the first commercial city gas distribution project in India. Indraprastha Gas Company Limited (IGL) started city gas distribution in Delhi. commercial. Mahanagar Gas Limited (MGL) started city gas distribution to domestic. Subsequently. GGCL currently under British Gas management developed distribution network in the Bharuch and Ankleshwar cities. In Gujarat. Similarly in 1998. which ran from Hazira to Jagdishpur via Bijaipur As a pilot project first city gas distribution project was taken up with the help of ONGC at Vadodara city in 1972. Oil and Natural Gas Corporation (ONGC) started selling its associated gas to the neighboring industries in the 70s. Tata and RCF. The gas pipeline networks were laid / owned by either ONGC or the customers. With the gas discovery in south bassein of Mumbai shores. they expanded their network to Surat. 17 Example of City Gas Distribution City gas distribution involves the distribution of natural gas in the form of : 1. PNG (PIPED NATURAL GAS) . CNG (COMPRESSED NATURAL GAS) 2. Although its combustion does produce greenhouse gases.4. usually in cylindrical or spherical shapes CNG is used in gasoline internal combustion engine cars that have been converted into bi-fuel vehicles (gasoline/CNG).0. Physical properties Non-toxic: Natural gas being sulfur/lead free. will rise above ground level and disperse in the atmosphere.012%-0.2% 0. CNG is made by compressing natural gas (which is mainly composed of methane (CH4). medium-duty delivery trucks. In response to high environmental concerns and fuel prices. its use substantially reduce harmful engine emission.4.5% – 91. it gives out carbon dioxide and water vapour. diesel.3% . Colourless: Natural gas is colourless. When natural gas burns completely. it is a more environmentally clean substitute to those fuels.5% . to less than 1% of its volume at standard atmospheric pressure.5% 3% . . CNG is starting to be used also in light-duty passenger vehicles.5% 3.18 COMPRESSED NATURAL GAS (CNG) CNG is a fossil fuel alternate for gasoline (petrol). in the case of leakage. or propane fuel.the very component we give out while breathing. Natural gas vehicles are increasingly used in India.2% 0. but disperses quickly when released).212% 100 1. at a normal pressure of 200–250 bar. school buses. Lighter than Air: Natural gas which is being lighter than air. and it is much safer than other fuels in the event of a spill (natural gas is lighter than air. It is stored and distributed in hard containers. and trains Typical composition of CNG: COMPONENT Methane Ethane Propane CO2 Others Total PERCENTAGE RANGE 90.  Lack of knowledge about CNG.Benefits of CNG  Environment friendly and hence better health  Economical.  Higher Infrastructure cost.  Safer  Very low particulate emission  Low emission of air borne toxins  Negligible emission of oxide of sulphur(SOX)  More quiet operation.  Much more expensive distribution and storage  High vehicle cost  Shorter driving range  Much heavier fuel tank .  Requires high pressure cylinder for storage  Shorter self-sufficiency (but there is dual fuel option available). 3.  Higher conversion cost of vehicles. having less vibrations and less odour than the corresponding diesel engines.  Boot space occupied by cylinder. Limitations of CNG  Non availability at all locations.  Requires high pressure to increase storage energy density.19 Odourless: Gas in its natural form is odourless. ethyle mercaptant is later added as odorant so as to detect the leakage 2. however.  It is totally combustible containing 94% of combustible material and does not leave any residues. PNG is safe  The property of natural gas is that it catches fire when it forms a mixture of 5-15% mixture with air. the PNG which is supplied through the MDPE from DRS. hospitals. restaurants.  Necessity of changing the cylinders are not required.20 PIPED NATURAL GAS (PNG) The second category of the gas in the CGD is the PNG. The major difference between the CNG & PNG is that.   as. 13 Comparing the PNG & LPG. Industrial PNG – Convenient fuel The PNG is called the convenient fuel due to the following reasons. PNG is comparatively cheaper than LPG.  It contributes to a cleaner society.  It does not darken the vessels.  Useful during the emergency.  No problem of space occupancy as cylinders  The payment is after consumption based on how much consumed. the pressure is 2-4 bar. The billing is done based on the consumption by the customer. Applications of PNG         Following are the applications of PNG Cooking purpose Heating/ furnace Air conditioning Gas fire places Hotels. • Continuous supply of gas. whereas LPG is combustible when at its 2% mixture with the air . the PNG installation inside the premises is very less and is only at pressure range of 21mbar. Comparing LPG. The technical factor involved in this is the flammability limit of the gas  . it being denser than air settles down in case of leakage.21  Since natural gas is lighter than air. Whereas. in cases of leak. around 14.Large quantity of LPG i. which is highly hazardous. . it just rises up and disperses in to the air.2 kg of LPG is compressed into the LPG cylinders.e. City Gate Station (CGS) 2. 5.1 City Gate Station CGS is the starting point of the city gas distribution system.2 Pressure Reduction skid The pressure reduction skid is installed to reduce the pressure of the incoming gas from the source from the range of 30-49barg to 26barg.1. 6. High efficiency filter separators are used for the removal of liquid and solid particles from the incoming gas stream over the entire operating range. The filter is normally designed to withstand a pressure in the range of 30-49 bar. This consists of configuration. 5. Service regulator 5. Meters.22 City Gas Distribution System The system consists of 1. Filter skid Regulating skid Metering skid.1. Odorization unit 3. the filtration skid ensures the pure gas distributed to the line. The gas outlet from the processing industry is cautiously maintained at free of impurities. . 5. District Regulating Station (DRS) 4. it receives the natural gas from the supplier based on the demand.1 Filtration skid The skid has been designed in such a way as to accept a single stream only. Pipeline system. Orifice flow meters finds its use as a large pressure drop is required. pressure at the inlet and outlet joints.2 Odorization unit One of the measure safety factors is Odorization of the natural. The various parameters such as temperature in the various sections of the line.  Filtering skid  Pressure reduction skid The normal range of pressure in the District Regulation System is inlet: 19-26barg. outlet: 2-4barg.1. flow inlet and outlet are controlled by the SCADA systems in the control room Therefore the gas is passed through the filter for removal of liquid and solid particles and then it is passed through the regulating skid to reduce the pressure of the gas from 26-30 to 19 bar. The various components in the DRS includes  Slam shut valves for controlling the flow.3 Flow metering skid Flow meters are installed to for a single stream.3 District Regulating Station DRS is the next setup of the CGD. The maximum allowable flow inside the DRS is in range of 500010000SCMH. which is going to be used by the customer. The location of the District Regulation Station mainly depends on the requirements and demand. The normal flow meters used in the CGS is orifice plates. It is the interface between the steel grid network and the medium pressure network. where its joined to the PE line using the Steel – PE converter.23 5. The odorant generally used is ethyle mercaptant. after this the gas with this pressure is sent to the main metering skid for the purpose of measuring. For the safe distribution of the gas some smelling identification is required for leak detections. . 5. In this a single odorant or combination of two can be used. It is a device used to reduce the pressure from 19 barg to 4barg. The inlet to the DRS is from the steel line and the outlet is also the steel line. The unit consists of a pressure vessel filled with odorant and a special injection pump which pumps these chemicals into the natural gas line by considering flow rate. The odorizer injected should be of 12PPM as per the Indian standards. 5. 24 District Regulating Station 5. The types of regulators that are used generally depend on the number of connections. generally located at customer premises for maintaining supply pressure and designed to maintain safe condition even in the event of rupture in the regulator downstream section. It reduces the pressure from 4 bar to 110 mbar to the service line.3 . According to this various types of regulators are available as shown in Figure 5. These regulators maintain the required maximum and minimum pressure with shutoff device.4 Service regulators These are installed before tertiary PE lines. 1bar. with maximum operating pressure of 0.e. Meters are used based on the type of the customer and his requirements. It depends on the demand and accuracy needed for billing. For Industry purpose both diaphragm and RPD (Rotary Positive Displacement Meter) or turbine meters are used.25 Types of Service regulators 5.6 m3/hr.017 to 2. . Billing of gas is usually done based on the standard conditions i. which is having a flow range of 0. Meter used for the domestic customer is of diaphragm meter. SCM. It decides or gives the information about the amount of gas sold to the customer.5 Metering Meters are the important part of the CGD. 26 5.5.1 Selection of meters Following criteria shall be considered for the selection of meters  Rangeability or Turndown ratio  Accuracy required  Suitability of meter with quality of gas available  Pressure requirement  Calibration & maintenance requirement  Size & weight  Installation and maintenance constraints  Operability  Cost  Gas quality Turndown ratio It is a flow measurement term which indicates the range of a specific flow meter, or type of meter that is able to measure with acceptable accuracy. It is also called as rangeability. It is significant when choosing flow meter machinery for a specific application. If a gas flow to be measured is expected to vary 100000 m3/day and 1,000,000 m3/day, the specific application has a turndown ratio of at 10:1. Therefore a meter requires a turndown ration of at least 10:1 The turndown ratio of each type of meter is limited by theoretical considerations and by practical considerations. For example, orifice meters create a pressure drop in the measured fluid proportional to the square of the velocity. Therefore the range of differential pressure can become too large and compromise accuracy. It can also create process problems such as hydrate formation, and in the case of measuring the discharge of a compressor, there is a limit to how much pressure loss is acceptable. 27 Turndown ratio is one of a number of considerations in choosing a meter type for an application. Some other considerations are price, maintenance cost, accuracy, the fluid type and the velocity of the flowing fluid.  Diaphragm meters are considered to have a turndown ratio of 80:1.  An orifice plate meter has a practical turndown ratio of 3:1. This means that if an orifice meter with a design flow rate of 20,000 m³ per day is installed, the flow range that the meter can measure accurately will be between 10,000 m³ per day and 30,000 m³ per day.  Turbine meter has a turndown ratio of 10:1.  Rotary displacement meters have a turndown ratio of between 10:1 and 80:1, depending on the manufacturer and the application.  Multipath ultrasonic meters often have a stated rangeability of 50:1. Meter selection matrix 28 Diaphragm meter: This is a kind of meter which uses a diaphragm i.e. a synthetic fabric called reinforced nitro rubber, which simultaneously fill and discharges the gas with a fixed volume to measure the quantity of gas passing through it. It is simple process of alternately inflated and deflated by the pressure of the gas. This movement is causing the index to register volume as well as causing the valves to become repositioned for the next .29 Typical Connection of Diaphragm Meter WORKING Step 1 The left valve is positioned such that the left diaphragm is being filled with higher pressure unmeasured gas while the left case is emptying slightly lower pressure measured gas to satisfy the demand. 6. Please note that the right valve is positioned such that there is no activity in the right diaphragm or right case Step 2 The left valve is now positioned such that there is no activity in the left diaphragm or left case. This movement is causing the index to register volume as well as causing the valves to become repositioned for the next cycle. .30 cycle. The right valve is position such that the right diaphragm is being filled with higher pressure unmeasured gas while the right case is emptying slightly lower pressure measured gas to satisfy the demand as shown in figure 5. The 28 meter will remain stopped until a demand is required.31 Step 3 The left valve is positioned such that the left case is being filled with higher pressure unmeasured gas while the left diaphragm is emptying slightly lower pressure measured gas to satisfy the demand. The right valve is position such that the right case is being filled with higher pressure unmeasured gas while the right diaphragm is emptying slightly lower pressure measured gas to satisfy the demand. The cycles will continue and the meter will measure until the demand is shut off. which results in a minute differential pressure. the pressures equalize and meter movement and measurement stops. will start the meter measuring again . Please note that the right valve is positioned such that there is no activity in the right diaphragm or right case Step 4 The left valve is now positioned such that there is no activity in the left diaphragm or left case. This movement is causing the index to register volume as well as causing the valves to become repositioned for the next cycle. Even the slightest demand. Once the demand is shut off. This movement is causing the index to register volume as well as causing the valves to become repositioned for the next cycle. The follower magnet of the magnetic coupling drives the counter to register volumes metered at the operating conditions. at low. These meters are designed to measure natural gas. and thus. Types of Turbine Meters . and non corrosive gases. the rotating speed of the turbine is proportional to linear speed of the gas.5. 6. The gas exits the turbine rotor through a flow ring and an expanding exit channel to minimize pressure losses. 3.32 Types of Diaphragm meters Following are the different diaphragm meters that are available based on diaphragm gauges 1. 4. 2. G16. The movement is mechanically transmitted to the totaliser through the magnetic coupling. Operating Principle The flowing gas enters the meter through a built-in flow conditioner (1) that conditions the flow profile and increases the gas velocity. The turbine rotor blading (3) is designed with overlap to give complete guidance to the flowing gas and extract the maximum energy at low gas velocities. & G2. The flow of gas turns turbine wheel. The rotation of the turbine rotor is transmitted via a gear train and transferred from the pressurized meter body to the counter (5) by a gas tight magnetic coupling (4).6. The turbine wheel‘s angular velocity is proportional to the average gas velocity flowing through the meter. medium or high pressure. G6. and various filtered. 5. The gas continues along the flow channel (2) and enters the turbine rotor. G1. They are used to measure medium to high gas flow. G4. G25 Turbine meter Turbine gas meters are flow meters. G10. These meters are volumetric meters.  2 pistons. Working Principle The flow of gas moves the pistons and each rotation traps and transfers a specific volume of gas.  A magnetic coupling to transmit the movement of the pistons to the totaliser (4). which are synchronized by 2 rears and which rotate in opposite direction (2). The movement is mechanically transmitted to the totaliser through the magnetic coupling Description A RPD meter is made of 5 main parts:  A measuring chamber that is limited by the body and the 2 base plates (1).  2 lubrificant covers (3).33 Turbine Meter RPD METER RPD stands for rotary positive displacement meter.  A totaliser to register the measured gas(5). . Correction Factor Correction Factor means whenever customer use the Gas beyond the Standard Conditions means 1. But the company charges them on the bases of standard cubic meter. Correction factor can be calculated for a particular set pressure as follows . This is usually done manually by finding the correction factor for each meter based on the set point of the customer meter.01325 Bar Pressure and 288.15 0K Temperature.34 GAS Meter set assembly Billing of diaphragm meters Usually these meters read or show the reading of gas consumption by the customer in normal cubic meter. we have to multiply the m3/h with factor which is called as Correction Factor . gas mains or distribution mains normally constructed using steel pipes and connects one or more transmission Pipeline to respective CGS or one or more CGS to one or more DRS. A typical CGD network should consist of the following Primary network: A medium pressure distribution system comprising of pipelines.Pipeline System Pipeline network consists of steel pipeline. V2= measured volume. Tertiary Network: A service pressure distribution system comprising of service lines. industrial. and domestic consumers. service regulators and customer /consumer meter set assemblies constructed using a combination of thermoplastic (MDPE) piping and GI /copper tubing components. 6. T1= base temperature. Steel reinforced rubber hose shall conform to IS: 9573 . polyethylene pipeline. T2= operating temperature. Secondary Network: A low pressure distribution system comprising of gas mains or distribution Mains usually constructed using thermoplastic piping (MDPE) and connects DRS to various service regulators at commercial. V1 = standard volume. The maximum velocity in the pipeline network should be limited to 100 ft / sec (30 m/sec) immediately after pressure regulating instrument. The network should be sized for maximum flow velocity of 100 ft / sec (30 m/sec).35 Where. galvanized iron pipeline and finally copper pipeline. P1= base pressure. Tubing / Hose pipe for connecting consumer meter set assembly and consumer appliance: The connection between consumer meter set assembly and gas appliance (provided by consumer) may be made by GI pipes or copper tubing or steel reinforced rubber hose. P2= operating pressure . g. • Electro fusion jointing. water lines. It is done under the direction of the company. • PE Excavation. • PE Valve chamber.1 Detailed Process Of PE Laying.36 LAYING OF PIPELINE NETWORK Laying of the pipeline starts after the issue of right of issue and the route of pipelines under the City gas pipeline project. curves. Excavation works are performed so as to enable the pipe to be laid in conformity with the levels depths.1 PE Excavation Excavation for the PE starts after the issue of right of issue and the route of pipelines under the City gas pipeline project. cables. They are protected and fenced. specifications. • The trial holes are normally preplanned i. slopes. • PE route marker. The various steps or the technical requirements for the PE laying are as follows. pipelines belonging to other companies. Proper care is taken while trenching to ensure all underground structures and utilities are disturbed to the minimum.1. dimensions and instructions shown on drawings. • Tap off from in operation gas mains. the location of between the trial holes is normally at a distance of 25m. slopes. specifications. 6. Excavation works are performed so as to enable the pipe to be laid in conformity with the levels depths. These holes are not closed immediately. telephone wires. dimensions and instructions shown on drawings. The crossings wherever necessary is provided and .e. • Trail holes refers to the small pits which are generally dug before the actual excavation process for determining the pipe route and locate other underground plant or investigate possible 38 obstruction if any e. • PE Trenching • PE testing. curves. 6. • The excavated trench is maintained on stacked centre line as per the sheets approved and also taking into account of the curves of the pipelines. They are excavated to a depth of pipe and an addition of 250mm. The trial holes are planned in such a way that there are no abandoned trenches and also to avoid insufficient trial holes. The detailed process of laying of the PE is handed over to the contractors. • PE laying. where there is any danger of landslides the pipeline trench is maintained open for time required to lay the line i. • The bottom of the trench is normally maintained in the square form to the maximum extent with the equipments so as to avoid the hand grading at the bottom of the trench.5m  Minor water crossing or canal 1. In places. by hand. • Trenching is made in sufficient slopes on sides in order to minimize collapsing of the trench. The design of the depth of the trench varies for different locations as follows. the work in that area is completed in less time and covered. The bottom of the trench is made free of loose rocks. PE Trenching Trenching refers to the making of holes i. opening the ground wide apart.e.5m  Rail or road cased crossing 1. A stretch of 12m is allowed to remain excavated before joining or back filling. The soil stability is analyzed in areas like drainage. For distribution main 1. • Any kind of rock which cannot be drilled using sledge hammer. Machine Boring. This happens when hard obstructions are encountered. It is classified into 2 types.  Boring.37 maintained for the general public property owners or tenants to cross and also to move any stock from one side of the trench to another. chisel is considered as ‗hard rock.5m  Uncased or cased road crossing 1. pebbles and trim protruding routes from the sides of the trench wall.e. machine boring is made use of. ditch etc.e.5m .  Open Cut. When the boring is not possible by red boring. Red boring refers to the boring of ground without opening the ground wide apart using the normal tools i. Any other Plain cement concrete (PCC) or Reinforced cement concrete (RCC) encountered during excavation are removed in supervision of authorities as the cost of removing those type of obstructions is high. Red boring. g.38  Normal areas 1. The crown of the backfilled earth is maintained between 50mm and 100mm and is free from sharp edged stones & boulders.And 300 where the gas pipe to be laid is on a similar alignment to the other assets. other than electric cables where the clearance is 300mm.   150 mm where the gas pipe crosses other assets. This is maintained strictly for the protection of the gas pipeline. The site is maintained neat and clean without causing any nuisance to the public until the completion of the work. In places where this clearance cannot be maintained due to various reasons. In case of any difficulties in maintaining the required depth due to unavoidable factors the new depth shall be decided and put in to effect in the particular area only. • In cases where rock. The surplus material is neatly crowned over the trench and adjacent excavated areas on both sides of the trench. before commencing of the excavation the ‗caution board‘ & ‗information board‘ as per the standard size. gravel. All the trenching works are carried out with proper caution. suitable barrier protections are installed between the pipe and the service line like the electric cable. RCC half round hume pipe is constructed along the trench. lumps of hard soil or materials are encountered at the time of trench excavation. While back filling the mud or the soil is cautiously done such that there is no extraneous material or hard lumps of soil near the laid pipeline which could damage the line or the coating or leave void spaces in between the fillings. Little extra allowance of mud is put over the trench such that it comes to the normal level during settling. sufficient sand is placed around and over the pipe to form a protective cushion extending at least to a height of 100 mm above the top of the pipe. • The width of the trench is maintained in wide enough to provide bedding around the pipe and to prevent damage to the pipe inside the trench. The distance between the ground and the bottom edge of the pipe is 50 mm for 63mm diameter pipelines and 100 mm for pipes larges than 63 mm which included the 90 and 125 mm pipes. . • All the works in the municipal or public roads are required to be executed as per there codes and conduct with a view to cause minimum inconvenience to pedestrian and vehicular traffic.2m • The above mentioned depths may vary depending on the locality. • In case of rain dewatering is done prior to back filling. E. • The following clearances are provided between the external wall of the gas pipe and the external surface of the other underground assets in the locality. shape and color are installed at the site. for a time period of 24 hours. • PE warning grid or mat are placed on the distribution main and on service lines inside premises after backfill of the trench up to a height of 300mm after the sand bedding. Special compaction methods are adopted. • Experienced supervisor is always present at the site to decide on various factors in the required situations. The warning mat is unrolled centrally over the pipe section and thereafter the backfilling is done. During the backfilling of the trenches in private society premises. else vice versa. • Turf is replaced in highly developed grass area. The reading of pressure is taken for every one hour. The progressive pressure testing for the main pipelines and all the PE 100 pipelines SDR11 are carried out at a pressure of 6barg. • The back filling is assumed to be complete after the joining of pipes are complete. In lesser grassed area top soil are replaced during the restoration process. • All the excavated material which will be required for backfilling are kept separately and properly. Excess soil in the area is cleared off the site and is dumped at suitable location. The leakages in the pipeline can be found out by this method. municipal premises and panchayat premises. • Trench excavated in dikes which belonging to the property of railways or which are the part of the main roads are graded and backfilled in their original profile and condition. alternate arrangements are done temporarily for the traffic and the pedestrians. • The stabilization period throughout the length of the pipe is normally half an hour which is assumed. A prior information of excavation is given to the people in the area where the work is to commence in advance for their prior arrangements. In areas of roads or pedestrian places the refilling are done immediately to avoid inconvenience to the public.39 • Thorough and proper compaction is done where in places where the trench is dug like. A third party officer is also made to be always available on the site. Any unaccountable loss in pressure in the line during the test period implies the leakage in the pipe. PE Testing • Pressure testing is carried out with compressed air or nitrogen gas. In areas where the restoration works cannot be completed immediately. The backfill materials if required are supplied. the drive or road ways. All the measuring instruments which are used are totally tested . watering and ramming or mechanical compaction are carried out. PE pipe squeeze-off utilizes the ductility of PE by allowing the pipe to be squeezed together using relatively simple but specially designed squeeze-off tools thus preventing the flow of fluid and isolating the pipe section. The design of PE pipe networks should follow conventional network practices with the installation of valves at convenient or critical locations.  Gas sampling equipment  Squeeze off tool.40 and approved by the company. Squeeze-off is used in routine and emergency situations to stop or nearly stop flow in PE pipe by flattening the pipe between parallel bars. It is . The maximum allowable range of oxygen in the line is 0-2%. The valves can then be operated to isolate sections of the pipe network for maintenance.2%. The oxygen content in the line is also checked up. All the testing are witnessed by the company authorities. • A record of all the purging plan before the commencing of the purging work is kept as a reference drawing. hoses and connections. The methane content in the gas is tested using the specified meters. The nitrogen cylinders used are checked for their label. The squeeze off tools are generally mechanically operated up to about 125mm diameter and hydraulically operated for larger diameters.  Fire extinguisher. • Purging is also done with the help of nitrogen. Normally the oxygen content in the line is 0. It is important that only specifically designed tools are used and that the squeeze-off controls are set for the specific diameter and SDR of the pipe in order to control the degree of compression of the PE pipe and prevent any damage. However squeeze-off equipment is not readily available for the largest diameters of PE pipe.  Purging adaptor  Purge stack with flame trap and gas sampling point. • The testing is done with all necessary regulators. • The testing carried out during the commissioning process includes the testing of the charged line for the composition of the gas. The plan includes the provision of the following materials and equipments. which are in good condition and working order. certification and tests. Additionally however PE pipe networks have the advantage that more localized isolation can be implemented by the use of pipe ‗squeeze-off‘. the MDPE coil is uncoiled smoothly inside through proper process and care inside the trench ensuring no damage to pipe coil during laying. When squeezing larger pipes. Reference should be made to the manufacturer‘s instructions. It is important that the correct saddle fitting is used compatible with the equipment being used. and there are limits to the pressures that they can sustain. is not expected to cause damage to the PE pipe. it may be necessary to vent the pipe in-between two squeezes-offs. Adequate and sufficient trench is provided for commissioning process or providing tap off. A saddle fitting needs to be fixed to the pipe.5m by 1m. roots. The reopening of any trench might be required during the commissioning process. When seepage is not acceptable. However squeeze-off is not recommended to be done more than once at any location. If repeated flow control is required a valve or an appropriate flow control device should be installed in the system. stones. which regains its circular cross-section after the tool is released. The maximum trench dimensions which might be required during the commissioning is 2. . through which the inflatable bags are inserted.41 important to follow the manufacturers instructions when using these tools and to use tools appropriate for the pipe diameter and SDR. PE laying • The laying of the MDPE pipelines commence only after the ensuring of the proper dimensions and clean surface of the trench. After ensuring of all the above factors. some seepage is likely. • It is ensured that the pipe caps are provided before the lowering of the pipeline. using the correct tools. The trench bottom is made to be free from the presence of cuts. Also the tools need to be capable of resisting the operating pressure of the pipe. Any work performed must be downstream of the second squeeze-off. The trench after this is released for backfilling leaving adequate lengths open to the ends for joining. . particularly at higher pressures. stakes and rock projections up to 150 mm below the underside of the pipe and any other material which could make perforations or tearing of the pipe wall. Properly implemented squeeze-off. Complete flow stoppage may not occur in all cases. Squeeze-off is not intended as a means to throttle or partially restrict flow. debris. Inflatable bag flow stopping equipment can also be used for PE pipes. such as the fusion time. incorporating an electrical heating coil which melts the plastic of both the fitting and the pipe. Similarly after lowering of the pipe the trench is filled with sand around and up to 100mm from the top of the pipe. causing them to fuse together . • Proper inspections of pipes and fittings are done before the releasing of the latter from the store and the defects are reported to store authorities. sometimes called melt and freeze zones. Electro fusion Electro fusion is a simple method of joining PE pipes in circumstances where butt fusion is not practicable. Electro fusion jointing • Jointing of the pipes is normally carried out by the electro fusion process based on the requirements. elbows. are formed after energizing the coil. such as where valves. When the coil is energized. An electro fusion control unit (ECU) supplies the electrical energy necessary to heat the coil. Following the termination of the heat cycle. The length of these zones is particularly important. • Proper care is taken for PE pipe and fittings after issued from the store till the transporting storing sheltering the pipe near the trench. The . and tees must be added. On swiping the sensor over the bar code the required setting time and temperature are set and on click of start the process starts. the material adjacent to it melts and forms an expanding pool which comes into contact with the surface of the pipe. Hot and cold zones. Proper care is taken during the EF jointing such that there is no failure of the joint. The characteristics of the fitting to be welded. The continued introduction of heat energy causes the pipe surface to melt and a mixing of pipe melt and fitting melt takes place. are registered via a barcode on the fitting. Prefabricated fittings are 43 used. this is vital to produce a good weld. the fitting and the pipe are left to cool and the melted material solidifies to form a sound joint.42 • Before lowering of the pipeline a sand bedding of fine soil is done at the trench bottom. Each zone ensures that fusion is controlled to a precise length of the socket of the fitting and that the melt pressure is also controlled throughout the entire jointing process. lowering of pipe in the trench or pulling of the pipe through the trench such that no external damage is caused to the pipe. uncoiling of the pipe by proper process and sufficient man power. pressure and time. to remove any dust residue. to a depth 44 of approximately 0. are controlled by the ECU which is programmed to establish these parameters from the barcode read from the fitting itself. Metal files. The resulting joint. It is a usual practice to make a joint of electro fusion fitting on the same day of laying. The prepared surfaces must completely dry before proceeding. Before jointing the packing sand is placed under the pipes on both the sides of the joint to keep the pipes in line and correct during the jointing process. methyl ethyl ketone (MEK) or other solvents are not recommended for wiping the scraped surface. as recommended by the pipe or fitting manufacturer. The basic fusion parameters: temperature. • The time of electro fusion for the normal 90mm MDPE is around 42secs and a temperature of 48 deg C is to be maintained. water mud etc which would have entered the pipe during the laying process. Pipe clamps or other approved methods of restraining. emery paper etc are not suitable end preparation tools. The pipeline is normally flushed with air to remove dust. This reading is noted from the meter.43 precisely controlled pitch and positioning of the coil in relation to the inner surface of the socket ensures uniform heat distribution. The alignment clamps with correct size are used whenever necessary to align the pipe during the electro fusion jointing cycle. The ECU also provides a permanent record of the procedure followed. The pipe surfaces to be fused need to be scraped to remove the surface oxidation layer prior to fusion. To prepare the jointing surfaces the pipe surface must be scraped with an appropriate pipe scraper. Following scraping the scraped surface must be wiped with an authorized Isopropanol impregnated pipe wipe. acetone.3mm. Methylated spirits. All the fittings related to electro fusion are according to the design standards. when properly made. as recommended by the pipe or fitting manufacturer. The effectiveness of electro fusion depends on attention to preparation of the jointing surfaces and ensuring that the surfaces to be welded have satisfactory contact during the welding and cooling cycles. In case of leakage the joint is redone with a separate coupler to prevent future damages to line. to remove the entire surface of the pipe over the area indicated. Compact ECUs are now available that allow in-trench electro fusion welding to be carried out safely by just one man. . is as strong as the original pipe and can withstand all the loads applied during routine installation and operation. • The electro fusion joint is inspected before the restoration of the trench so as to ensure the leakage. rasps. aligning and re-rounding the pipes during the fusion cycle should be used. The ratio of cement. • The cement.44 The various types of the joints which are used in the coupling or jointing of the MDPE pipes are normally 3 types Coupler Tee. coarse and aggregate 40mm is 1:4:8. The remaining PCC work around the precast frame is carried out to fix the precast frame on the chamber to avoid any displacement. Elbow PE Valve chamber • At certain areas the installation of the PE stop valves and the construction of the valve chamber is required. The necessary PCC work in the annular space is carried between PE pipe and brick wall for sealing. bricks. It includes conveying and spreading the stuff embankment within 200mm from the end of the cutting with all required lead and lift to required gradient and chamber. • The fix heavy duty RCC manhole chamber circular cover with square frame with the desired load capacity and the dimensions mentioned in the designed standard drawing. . The valve chamber can be constructed in any type of soil. coarse sand are supplied and the fine gravel (machine crushed). the number and type of flow stop devices to be used is to be determined by the company . The distance between each stop off valve is 1500m approximately for 125mm dia.45 • The PE stop off valves are installed in pipe system operating at the pressure above 110mbarg. • A 6mm smooth thick cement plastering work is to be done over the projected route marker including scaffoldings. The PE route marker shows the route of the laid pipeline.e. • The precast of RCC mix of 1:1. removal of temporary by pass. • In case of delay in construction of valve chamber on any charged or uncharged pipeline.5:3 is required for the route marker stone. • The flow stopping devices are used such as squeezers. The route marker stone is casted as per the design requirements. The Route marking process is to be completed before the commissioning process. curing etc. construction of valve chamber as mentioned above. This scope covers the necessary reopening of the charged pipe i. The number of live connections from the charged lines can be minimized by proper planning and synchronizing medium pressure network charging for a particular area. The distance between each route marker is approximately 300m. the PE stop off valve is properly wrapped and is backfilled in such a manner that the valve is not damaged. providing temporary bypass. This is done in case of emergency purposes. This is for the easy reference for finding the route. Tap of from charged gas mains • The taping process from the charged gas line is a tedious and time taking work. • The method to be used for each connection. pipe. These are used only on the MDPE lines as they have their property of regaining their after squeezing. squeeze off & cutting of PE pipe. For easy understanding of the route marker in the diagrams it is represented by the yellow color. pipe and 2000m for 90mm dia. • The route marker is normally laid for lines in which the pressure of the line is greater than 110mbarg. installation of PE stop off valve. PE Route Marker • The route marker can be defined similar to a milestone. 46 . 47 Pipeline Network In Dewas Line Diagram of Pipeline Network In Dewas . 48 . 17km 10.08 km 10.68km 10.23km No of DRS No of CNG station No of CNG station proposed No of DRS proposed : 4 : 1 :3 :5 . Pipeline network in dewas Total Steel line 8 inch steel line 6 inch steel line 4 inch steel line 31.49 INDUSTRIAL CUSTOMERS DOMESTIC CUSTOMERS About 167 houses are being connected with png connection till 30 th of june 2012. 50 Pressure regime of the distribution network in dewas . inch t= nominal wall thickness of the pipe. grade and weight of pipe may operate. An important pipeline design calculation is the maximum pressure at which a given size. D= nominal outside diameter of the pipe. and depends on the physical and chemical properties of the pipe steel The allowable operating pressure can be calculated using the formula Where. Maximum operating pressure determines how much gas a pipe line may carry. other factors being fixed. psig S= minimum yield strength. inch F = construction type design factor E = longitudinal joint factor T = temperature derating factor Factors considered during Design of Steel pipe 1. P= design pressure.Class Location Table Design factors for steel pipe .51 DESIGN OF STEEL PIPE Steel Pipe: Carbon steel is used in CGD Network. recreation area. outdoor theatre.52 Class 1 Offshore gas pipelines are class 1 locations. or other place of public assembly that is occupied by 20 or more people at least 5 days a week for 10 weeks in any 12month period. Class 3 This is any class location unit that has 46 or more buildings intended for human occupancy or an area where the pipeline is within 100 yards of a building or a playground. for onshore pipelines. 2. the days and weeks need not be consecutive. class 4 This is any class location unit where buildings with four or more stories above ground exist. Class 2 This is any class location unit that has more than 10 but fewer than 46 buildings intended for human occupancy.Pipe Seam Joint Factors Table : Pipe Seam Joint Factors . any class location 63 unit that has 10 or fewer buildings intended for human occupancy is termed class 1. 2 Allowable stress The allowable stress value S to be used for design calculation for new pipe of known specifications is Where. the larger would be the wall thickness required. Barlow‘s equation relates to hoop stress in the pipe wall to the internal pressure. in t = pipe wall thickness.Temperature Deration Factors Table 10. pipe diameter. the effect of the internal pressure is more than that of external loads. The minimum wall thickness required to withstand the internal pressure in a gas pipeline will depend upon the pressure. 0. the necessary minimum wall thickness will be dictated by the internal pressure in a gas pipeline. pipe diameter and pipe material. The commonly used formula to determine the wall thickness for internal pressure is known as Barlow’s equation. Therefore.3: Temperature Deration Factors . psi D = pipe outside diameter. Generally in most cases involving buried pipelines transporting gas and other compressible fluids. The larger the pressure or diameter. and wall thickness as Where Sh = hoop or circumferential stress in pipe material.72 = design factor based on nominal wall thickness. psi P = internal pressure. E = weld joint factor.53 3. in . Usually in CGDS we choose carbon steel pipe with smooth internal surface which is having absolute or internal pipe roughness of 400 μ in. in D = internal pipe diameter.54 3 Diameter of the pipe Diameter of the pipe is determined using many calculation including calculation of frictional losses. Reynolds no nd a standard table which gives the diameter according to the flow rate calculated 4 Thickness of the pipe Now the pipeline thickness is calculated as follows (considering design factors and type of pipe joints) 5 Calculation of Friction Factor Friction factor depends on the relative roughness of the pipe.0004 inches Where e = absolute or internal roughness of pipe. 0. in . The allowable grades for the city gas distribution for piped natural gas are PE 80 and PE 100. Classification: PE 100 MRS = 10 PE80 MRS = 8 The MRS is determined by the standardized testing for a longer period of time by the lower confidence limit (LCL). The available two grades of polyethylene pipes are PE80 & PE100. • PE pipe can be joined by heat fusion or mechanical fittings and does not corrode like metal . The various other reasons for the selection of the PE 100 are as follows. The used standard of pipe is PE 100 due to its characteristics of regaining its shape after squeezing. mainly the Medium Density Polyethylene (MDPE). flexible and available in long coils thereby making it easy to install and minimizing the numbers of joints in the piping system. This is a relationship between friction factor. pipe roughness and internal pipe diameter.5%LCL of the predicted long term hydrostatic strength at a temperature of 20 deg C for 50 years with internal water pressure. • First. The design of both these grades are based on the long term strength of the respective materials known as MRS(Minimum Required Strength). Merits of PE 100 The PE 100 having the minimum required strength of 10 which is greater than thePE80 is selected for the Outlet from the DRS. it‘s lightweight. The long term pressure results are extrapolated and the lower confidence limit is defined as a quantity with dimension of stress of unit in megapascal. Reynolds number. which can be considered as a property of the material under consideration and represents the 97. specially used in turbulent region DESIGN OF POLYETHYLENE PIPE Material Selection The polyethylene pipeline has various grades.55 The Colebroke-White equation is used for calculating the friction factor. • At approximately 1/8 the weight of comparable steel pipe. PE gas pipes have gained increasing importance in recent years because of their low cost and technical advantages over pipes made from more traditional materials. bending. internal pressure. installation is simpler • One important trend in the market for PE gas pipes is the emergence of PE 100 as an ideal material choice for gas pipeline systems. 4 bar and in some cases even 5 bar. • The main field of application for PE gas pipe has traditionally been local gas distribution with operating pressures of up to 1 bar. • It was decided that insertion of a PE100 pipe of 315mm SDR11 operating at 10 bar. It provides long-term resistance to a variety of service conditions such as: abrasion. point loading 72 and squeeze-off . was the ideal technical and economical solution. The choice of PE100 for the new pipe line was driven by the pressure rating of the material. direct burial. It can be installed as part of the customers piping system but is limited to supplying gas to outdoor grills and lighting fixtures Standard Dimension Ratio It refers to the geometry of the pipe. It is defined as the ratio of nominal outside diameter to nominal wall thickness . • This is the same material used to manufacture pex plumbing piping. Because of the nature of this product it is only approved for exterior underground use.advantages that give confidence to gas engineers the world over to specify PE pipe for their distribution systems. • However. the resistance to rapid crack propagation and the performance of the butt fusion joints. the resistance to slow crack growth. and with integral and robust joining methods. Because of it‘s cost and flexibility this product is mainly used as gas mains and supply line by the local gas suppliers.56 pipe. weathering. temperature and soil shifts. it has been proven in service that long distance lines with operating pressures of 10 bar can be produced from PE100. 57 dn = nominal outside diameter of the pipe. which is MRS (Minimum required strength) divided by the overall design service coefficient ―C‖ which is of the value 2 to 3. Where. The hoop stress is the design stress for the material. The pressure P is defined as the maximum operating pressure . S = maximum hoop stress P = internal Pipe pressure. Higher SDR indicates a thinner walled pipe at any given diameter. en= nominal wall thickness of the pipe (minimum). 58 . dispensers. The investment in a station is midway between daughter station and mother station. . while the quality of CNG dispensed to vehicle also decreases. The investment in daughter booster station is slightly higher than that of daughter station. The mobile cascade can be connected to the dispensing system through a booster. Daughter Station: The ―Daughter Station‖ dispenses CNG using mobile cascades. As opposed to the relatively simple task of storing a liquid fuel at near atmospheric pressure and pumping that liquid fuel to the vehicle. Daughter-Booster Station: Installing a booster compressor can eliminate drawbacks of daughter stations.buses/autos/cars. These stations supply CNG to both vehicles and daughter stations (through mobile cascades). There is reduction in storage pressure drops. These mobile cascades at daughter station are replaced when pressure falls and pressure depleted mobile cascades is refilled at the ―Mother Station‖. Online Station: CNG vehicle storage cylinders need to be filled at a pressure of 200bars. Mother Station: Mother Stations are connected to pipeline and have high compression capacity. ―On line Stations‖ are equipped with a compressor of relatively small capacity. Types of CNG Station: There are four types of CNG Station: 1. cascades. natural gas refueling stations are able to take a relatively low pressure gas and compress that gas to high pressures for storage at the refueling station and /or on the vehicle. In mother station there is heavy investment towards compressor.59 CNG STATION Natural gas vehicle refueling stations differ significantly from their conventional liquid fuel counterparts. pipelines. the refueling time increase. The investment in a daughter station is least among all types of CNG station. tubing etc. 4. 2. which compresses pipeline gas to the pressure of 250 bars for dispensing CNG to the vehicle cylinder. Older CNG refueling stations were typically designed to deliver gas for on-board storage applications up to 2400 psig. Daughter booster (compressor) is designed to take variable suction pressure and discharge at constant pressure of 200 bars to the vehicle being filled with CNG. 3. Typically they have the facility of filling all types of vehicles. Newer refueling st ations typically operate at pressures greater that 3600 psig to service vehicles with maximum onboard storage pressures of 3000 psig. With time fill posts the quantity of fuel dispensed into each vehicle is not easily monitored and therefore time fill is unsuitable for public refuelling stations. rather than direct from the compressor. Refuelling is therefore slower and more suited for vehicles left overnight at a depot. such as buses. .60 Another Classification of CNG stations: Fast Fill: Fast Fill stations primarily utilize gas drawn from a storage bank previously filled by the compressor. The speed of fill is comparable to petrol or 90 diesel and is typically found on public forecourts. This method is always used where the exact volume of gas in each vehicle must be quantified. Time Fill: With time fill posts the vehicle is refuelled directly from the compressor without the need for storage cylinders. 61 Typical NGV Refueling Station Components  Compressor(s)  Drive(s). Electric or Gas IC Engine  Fast-Fill Dispenser and Slow-Fill Dispensers  Fast-Fill Fully Metered  Pipe. Valves & Fitting  Ancillary vessels  Instrumentation  Electrical Interconnect  Lightning / Static Protection  Pressure Regulators (Dome Load)  Storage Cascades (Both DOT and ASME)  Flow Limiters  Fire Detection System  Electric Equipment  Lighting & Appliance Panel  Compressor Motor  Control Panel  Annunciator Panel  Junction Boxes  Conduits  Conductors  Grounding  Lighting Fixtures . This arrangement minimizes the likelihood of combustible gas leakage to the crankshaft/connecting rod housing. referred to as single-acting. Double-acting reciprocating compressors use both sides (strokes) of the piston to perform alternating compressions in the same cylinder per crankshaft revolution. Other design characteristics of reciprocating compressors include lubricated and non-lubricated designs. This provides a straight-line motion to the piston rod and simplifies sealing.5. At high output pressures (above 3000 psig) lubricated compressors are typically specified.62 Compressor Compressors are the largest single cost item in the refueling system. as shown in Figure 15. In a crosshead design as presented in Figure 15. Compressors used for high pressure ratio service are almost exclusively of the reciprocating type. a separate crosshead linked to the connecting rod is used with a piston rod linked to the piston. Reciprocating compressors used for high pressure natural gas service can be defined further as crosshead or trunk-piston compressors.5. For reciprocating units designed for high . as well as air-cooled and water-cooled designs. relies solely on the piston rings to prevent the escape of high pressure gas to the crankshaft/connecting rod casing. The basic reciprocating compressor is a single cylinder compressing gas on only one side of the piston. The trunk piston design. Intercoolers are generally used between the stages to increase compression efficiency as well as to lower the gas 109 temperature that may become undesirably high (as given by the following equation: especially for high compression ratios. drawing in order from the lowest to the highest pressure ground storage vessels. Therefore. multistaging may be required from a purely optimization standpoint. Compressors designed for compressed natural gas service (< 3. In cascade storage operation the compressor fills the ground storage vessels. 4. Compression ratio—dynamic units. 6. and include the following: 1. Storage operation by cascade involves individually-actuated storage vessels controlled by valves switched in sequence. although small-sized units are designed with compression ratios of 8 or higher. In some machines. For multistaging the formulae used for calculating power is Ground Storage Refueling stations which utilize ground storage of compressed gas often do so in a cascade manner. 2. it becomes necessary to use multiple compression stages (in series). Discharge temperature—all types. double-acting pistons are used in the first stages and single-acting in the higher pressure stages. The compression ratio per stage is generally 93 limited to 4. 3. Pressure rise or differential—dynamic units. which in turn fill the vehicle storage cylinders. with increasing compression ratio r. and most positive-displacement units. 5. Mechanical stress (rod loading) problems—all types. Compression efficiency (energy requirements)—all types. Multistaging There are practical limits to the permissible amount of compression for a single compression stage.63 pressure service. as the pressures . if a greater compression ratio is desired. Furthermore. Cascade storage works on the principle that multiple independent banks of vessels can more efficiently fill a vehicle than bulk storage. multiple stages are required. compression efficiency decreases and mechanical stress and temperature problems become more severe. multiple compression stages must be used. or operation of total storage capacity as a unit at a common pressure. Effect of clearance—reciprocating units. The limitations vary with the type of compressor.600 psig) typically have 4 or 5 stages. Whenever any limitation is involved. For example. State-of-the-art in high pressure natural gas metering is represented by Coriolis mass flow meters. a two-position fill post assembly without metering is roughly $1000. unit price.000. A single maximum pressure can be set for the storage facility. Ground storage vessels can be constructed to either DOT or ASME code.000 SCF each. such as would be suitable for a public refueling station. and total sale amount.64 vary with time.000. to as much as $25. Refueling station storage of compressed gas is an option for fleets that wish to reduce compression requirements. Dispenser Dispenser costs for NGV applications vary according to the number of hoses and the necessity for metering. These seamless pressure vessels are designed for natural gas service and do not require any periodic recertification as would be the case for DOT type ground storage vessels. For example. or each bank's maximum pressure can be individually defined.This increases the total cost for a two-hose dispenser with mass flow metering and readouts for total quantity. . Typical large ASME type storage vessels have storage capacities of over 10. DOT ground storage vessels typically have a 500 SCF capacity at 3600 psig. A two-hose dispenser with mass flow metering approaches $20. compacted. cylinder fittings should be arranged so that they do not face cylinder fittings of other cascade. well-drained noncombustible foundation. Cylinder installed horizontally in a cascade shall be separated from another cylinder in the cascade by a distance of not less than 30 mm. . The cascade shall be securely anchored to prevent floating in case flooding is anticipated. Cascade/bulk units shall be installed on a firm. This foundation may be in the form of a plinth with the raised edge at 2 M from the front and sides of the cascade forming a kerb upto which vehicles should be permitted. 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.65 CNG Storage system The cascade having horizontal cylinders and sited parallel to other cascade. CNG Piping All rigid piping. c) A quick action emergency and isolation shut off valve shall be installed near dispensing unit with easy approach and to remain closed when refueling is not being done. All the piping and tubing shall have minimum turns with adequate provision for expansion.66 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 and shall not permit gas to be trapped. fittings and other piping components shall conform to the recommendations of ANSI B 31. Adequate means shall be provided to prevent the flow or accumulation of flammable or combustible liquids under containers such as by grading. b) Master shut off valve with locking arrangement in close position. packing and any other materials used shall be compatible with natural gas and its service conditions. Gaskets. . in case natural gas is used the suitable safety measures to be adhered to. vibration and settling. The testing to be done by inert gas. shall be installed in steel outlet pipe outside but immediately adjacent to the gas storage unit to isolate all downstream equipment from the gas storage unit. jarring. C. temperatures and loading to which they may be subjected with a factor of safety of at least 4 based on the minimum specified tensile strength at 20 deg. All the elements of piping should be designed for the full range of pressures. All the piping and tubing shall withstand a pressure equal to that of safety relief device and tested accordingly after assembly. These valves shall be within fencing of storage unit. Rigid pipelines shall have welded joints between their respective components. contraction.3. Valves A minimum of four shut off valves shall be fitted between the gas storage unit and vehicle refueling filling nozzle as explained below: a) Each CNG storage unit to have quick action isolation valve in the steel supply pipe immediately adjacent to such storage unit to enable isolation of individual storage unit. pads or diversion curbs. tubing. This valve shall be outside the fencing. Exterior piping may be either buried with suitable corrosion protection or installed 30 cm. above the ground level with supports and protection against mechanical and corrosive damage. Compressor Station The piping and its fittings upto the battery limit of CNG installation shall conform to ANSI B 31. The pressure gauge shall have dial graduated to read approximately double the operating pressure but in no case less than 1.8 or equivalent. Compressor shall be designed for use in CNG service and for the pressures and temperature to which it may be subjected under normal operating conditions conforming to API 618/ API 813 or equivalent standard and Flame proof electric motor and associated fittings should conform to IS:2148 suitable for class I division I group II area. All these valves and other elements of piping shall be suitable for the full range of pressure and temperature to which they may be subjected.4-mm diameter at the connection where pressure gauge is mounted. . The CNG storage unit shall have an opening not to exceed 1. These valves are to have permanent marking for service rating etc.67 d) A vehicle refueling shut off valve shall be installed for each flexible vehicle refueling hose to control the refueling operation and shall have venting provision to allow for the bleeding of the residual high pressure gas after refueling is complete.2 times the pressure at which pressure relief valve is set to function. All pressure gauges in the installation shall be tested and calibrated at least once a year and records maintained. b) High discharge temperature shut down c) High cooling water temperature switch fitted to cooling water return line to shut the compressor in the event of a fault. Pressure Gauges Every CNG storage unit including each cascade or bulk storage tank shall be provided with a suitable pressure gauge directly in communication with them. Compressor shall be fitted with the following minimum devices : a) Pressure relief valves on inlet and all stages to prevent pressure build up above the predetermined set point. / month & year of manufacture d) Certificate of approval no.  Safety relief devices shall be installed with unobstructed full size discharge to a safe place on bulk tanks and cylinders in the vertical position with suitable rain caps. . e) Rated capacity (cubic meter per hour) f) Operating speed (RPM) g) Required driving power( in kW) h) Maximum & minimum supply pressures i) Maximum outlet pressure j) Certification for Natural Gas use Compressor and Compressor and its all fittings shall be tested for compliance of relevant standard suitable for CNG use by a competent person/ agency prior to installation. e) Low lube oil pressure shut down f) Low cooling water flow switch fitted to the cooling water return line to shut the compressor in the event of fault .  Piping shall be protected by safety relief devices in conformity to OISDSTD-132. inter stage & discharge pressures shut down.  Cylinder should have safety relief devices fitted in conformity to the Gas Cylinder Rules. These devices should have their outlet arranged in a manner so that in case of emergency a high-pressure gas escapes from these should not directly hit on operators/ persons in the close vicinity. g) A remote isolation switch for emergency shut down to be provided with manual reset at control panel. Pressure Relief Devices Safety Relief Devices may consist of either burst disc or safety relief valve and should conform to the requirements of OISD-STD-132. inlet.68 d) High. Compressor shall be provided at least the following clear and permanent markings readily accessible and easy to read in the installed position : a) Manufacturer's name b) Model c) Serial No.  All the safety relief devices shall have manufacturer's permanent marking indicating following :  Set pressure to start discharge  Discharge capacity in cum / min. .  All safety relief devices shall be tested at least once a year for proper operations and records to be maintained.  All natural gas devices not otherwise specifically mentioned shall be constructed and installed to provide a safety equivalent to those other parts of the system.  Gas detectors interlocked with compressor cut out switch in the electrical system of the compressor are to be installed which would automatically switch off the unit in case of major gas leak.  No shut off valves shall be installed between the safety relief device and the gas storage unit or bulk tank.69  Safety relief valves shall have a locking arrangement to prevent tempering by unauthorized persons. These valves should have a permanent tag indicating pressure setting. date of re-setting/ setting and capacity. Any adjustments to the safety relief valve shall be made by manufacturer or a competent person. Fittings ASME B16. globe stop and check valves (flanged and butt-welding ends) for the petrochemical.34 : Flanged valves.70 APPENDIX I List of specifications of piping materials used in the CGD network Steel pipe[2] API 5L: Specification for line pipes.9: Factory-Made Wrought steel butt welding fittings MSS SP-75: Specification for high test. tubular and other wrought steel fittings . petroleum and allied industries . threaded and butt welding ends IS 1239: Steel tubes. ASTM: A106 Seamless Carbon Steel Pipe which is for High Temperature Service ASTM: A333 Seamless and Welded Steel Pipe which is for Low-Temperature Service Galvanized iron pipes IS 1239 (Part-1): Steel tubes and other Wrought Steel Fittings . butt welding fittings MSS SP 97: Integrally reinforced forged branch outlet Fittings . wrought.Socket welding. petrochemical and allied industries BS 5351: Specification for steel ball valves for the petrochemical. threaded and welding end BS 5352: Specification for globe valve. petroleum and allied industries BS 1873: Specification for steel globe. steel wedge gate and check valves 50 mm & smaller for the petroleum. Valves API 6D: Pipeline Valves ASME B16. Pressure safety equipment EN 334: Gas pressure regulators for inlet pressures up to 100 bar EN 14382: Safety devices for gas pressure regulating stations and installations API 526: Flanged steel pressure relief valves Copper fittings BS EN 1254: Copper and copper alloys.20: Spiral-wound metal gaskets and metal jacketed gaskets for use with raised face and flat face flanges. Brass Ball Valves BS EN 331: Manually operated ball valves and closed bottom taper plug valves for gas installations in buildings .71 Gaskets ASME B16. round copper tubes which are used for water and gas in sanitary and heating applications. Plastic Valves ASME B16.40 : Manually operated thermoplastic gas shutoffs and valves in gas distribution systems. Plastic pipes ISO 4437: Buried polyethylene (PE) pipes for the supply of gaseous fuels. Seamless. Copper tubes BS EN 1057: Copper and copper alloys. Fittings with ends for capillary soldering or capillary brazing to copper tubes. In the project the various activities carried out in a city distribution system like the transportation of natural gas which includes operations in pipeline layout. Other subjects include health and safety . 6. 63. commercial and automobile sectors are being discussed.use of efficient material for transportation which resists corrosion. District Regulating Station.The total pipeline layed out in the city of dewas is being found according to its diameter individually . 32. laying of Polyethylene pipeline network and Compressed Natural Gas stations were carried out.20 mm diameters are used for distribution of natural gas throughout the city.72 CONCLUSIONS In this project studies on various City Gas Distribution systems like City Gate Station.proper networking of pipeline in the city are being discussed . Turbine meter.testing of materials used. Other activities like pressure regulation using regulators and valves are very important in transportation and delivery of natural gas for various consumers including domestic. and the equipments used in city gas distribution. Metering equipments like Diaphragm meter. industrial . Regulators. 4 inches and MDPE line of 125. Reciprocating Displacement meter. these are being discussed In the course of the project the pipeline network of dewas city is being coverd where carbon steel line of 8. . J. volume 2. Hayden.73 REFERENCES 1.. Elsevier publications. Frank Saxon. ―the Petroleum and Natural Gas Regulatory Act-2006‖.. www. New York. Ajay Tyagi. ―Pipeline Engineering‖. New Delhi.. R. Burlington-USA.wikipedia . 4. 4thEdition.google. Lewis publications.. New York. (19 of 2006). D. ―Gas Transmission and Distribution Piping systems‖. 2.com .. Frikken. ASME B31. www.. L.org 6. 3.. 2007. ―Tolly‘s Domestic Gas Installation Practice‖. Henry Liu.8a-2000. D. 2006. 5. Yarmush.