KM Bulletin Tech Papers on CNG and CGD and HDD Article

KM Bulletin (Edition 5) - December 2009 Page - 1

MMMaaannnaaagggeeemmmeeennnttt Edition 4 August -2009

A Quarterly Publication

MMMaaannnaaagggeeemmmeeennnttt Edition 5 December -2009

A Quarterly Publication

Knowledge Management Committee: Chairman Mr. J. Mathew ED (Power) & MR MECON-Ranchi Members Mr. A.K. Prabhakara DGM (Electrical) & HRD LPC MECON-Bangalore Mr. T.K. Saha DGM & Convenor, KMS Core Committee MECON-Delhi Mr. T.K. Biswas DGM I/c (IT Services) MECON-Ranchi Mr. A.K. Agarwal AGM, IM MECON-Ranchi Mr. R. K. Panda AGM, PP&EE MECON-Ranchi Convenor Mr. Sanjeev Kumar AGM I/c (HRD) MECON-Ranchi Edited by: Ms. Meenakshi Malviya APO (HRD) MECON-Ranchi

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Sharing knowledge is not about giving people something, or getting something from them. That is only valid for information sharing. Sharing knowledge occurs when people are genuinely interested in helping one another develop new capacities for action; it is about creating learning processes. Peter M. Senge, The Fifth Discipline Director (Commercial) and Director (Engineering) superannuated in the months of August and November 2009 respectively. In addition to their priceless contribution to the organization, they have set examples by their conduct of promoting such learning processes to foster the knowledge management venture in MECON. Encouraged by the response towards the previous two competitions, we are coming up with our third attempt in the series of KM Article writing competition. We are thankful to all the MECONIANS for their motivating and perpetual contribution towards this step of sharing the knowledge residing within MECON.

Whats Inside?

Content Page No. Topic, Rules & Guidelines for the next KM Article writing Competition

2

Status of Intra/ Inter section lecture sessions in last quarter & Document count growth in e-archive

3

KM News: International, India & At MECON Ltd. 4

Articles of the Best KM Contributors December 2009 6-61

MECON Limited

KM Article Writing Competition KM Article Writing Competition SeriesSeries

This time in the

series of KM A

rticle writing c

ompetitions, w

e will

try to showcase

the depth of ME

CONs knowled

ge and experti

se

in the field of

Services relate

d to Metals

With this editio

n we invite art

icles from sectio

ns concerned w

ith

Journey of ME

CON in Rolling

Mills &

other services r

elated to Metal

s

We are sure ou

r next KM Bulle

tin will be high

ly enriched

by your contrib

ution!!!


TOPIC: Journey of MECON in Rolling Mills & other services related to Metals Last date for entry: 30th January 2010

That gives you over a month to put your valuable experience in the form of an article, so get busy!

Why enter the contest?

Winner's Prize: The Management of MECON LIMITED will award the winners with a memento and a certificate. Publicity: The best articles will be printed in our next KM Bulletin along with photograph of the contributors. Knowledge: The main reason for entering the contest is propagation of your knowledge. Writing down your intellectual inputs is one of the most essential components of the learning process. This is a great opportunity for you to show that you are an individual with lots of information and you are willing to promote the knowledge sharing culture at MECON. Respect: Together with this you have bright prospect to get respect and feedback on your work from others interested in your work. This will be an incredibly valuable experience.

Rules of the Contest

It's simple. You have to write an article in English covering not more than 4 pages (written on one side) with a font size of 12 for Body text and 14 for Headings in Arial.

Only one (1) entry per person and group efforts will not be considered. The articles will be judged by the panel comprising of the senior officials of

concerned sections of MECON. Entries (in MS-Word format) are to be sent in hard copy to HRD Section, MECON,

Ranchi and a soft copy of the article with a scanned passport sized photograph of the author is to posted at [email protected]

Please ensure that your Name, Personal No., Designation & Section is mentioned in the article.

Please submit the article within the time stipulated and any article received after that will not be accepted.

Guidelines for Articles content

Strength, Experience and innovative practices belonging exclusively to MECON in

Rolling Mills & other services related to Metals Comparison of the Processes and standards followed by MECON with other

competitors in the same domain, i.e. Analyzing MECONs stand in the market The comparison may lead to finding of certain areas of improvement for MECON

and the individual may help in doing so by suggesting some practices based on his knowledge and observation of the market

The article should be reflection of the individuals own experience and learning about the above mentioned points

Intra/Inter-section Sessions @MECON, Ranchi

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Intra/Inter-section Sessions @MECON, Bangalore Intra/Inter-section Sessions @MECON, Delhi

Document Count Growth in e-archive (as on 4th December 2009)

S.No Title of the Session Section Date Presenter

1. Basic Terminology Relevant to Thermal Power Plant

PP & EE 07.09.09 Shri V. Trivedi & Shri Arun Minz (PP & EE)

2. Instruments Transformer Electrical 23.09.09 Shri M.K. Jaiswara, ADE (PT&D)

3. Performance Evaluation of System Generator

PP & EE 09.10.09 Shri D. Bose, ADE (PP & EE)

4. Blast Furnace IM 16.10.09 Shri S. Sengupta, AGM (IM)

S.No. Title of the Session Section Date Presenter

1. Awareness Programme on ISO 9001:2008 QMS

Quality Steering Committee

07.08.09 14.08.09 21.08.09

Mr. G.V Aruna,Mr.Supriya Ray & Mr.G.Krishna Kumar

2. Training Programme on "ISO 9001:2008 Version of QMS"

Quality Steering Committee

14.09.09 Quality Steering Committee

3. Interactive Training Programme

Vigilance 27.09.09 Mr. Solomon Yash Kumar Minz, IPS & CVO

S.No. Title of the Session Section Date Presenter

1. Solar system Electrical 07.10.09

Mr. Aashis Moyal, ADE

2. Pipeline Construction - I Oil & Gas 26.10.09 Mr. A. K. Jha, Sr. Manager (Projects)

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Based on data mentioned above, Quality Steering Committee from Bangalore is declared to be the Brightest Performer for this quarter.

CONGRATULATIONS!!!


LATEST KM NEWS KM @International level * KM World Announces Finalists for 2009 Promise and Reality Awards The winner is chosen from a list of Knowledge Management companies that provides innovative solutions for best knowledge management practices into their business processes. Some of the KM Promise finalists are: Alfresco : It is an open source enterprise content management system Autonomy : It provides technologies for computers to understand electronic data Cabinet NG : It is a provider of document management and workflow software Cormine Intelligent Data : It integrates sources of data to produce query results Expert System: It is a semantic indexing, search and analysis tool KM @ National level * 2009 Indian Most Admired Knowledge Enterprise (MAKE) Finalists Enterprise Sector Bharti Airtel Telecommunications eClerx Services Information & technology services Eureka Forbes Consumer products HCL Technologies Information & technology services ICICI Bank Financial services Infosys Technologies Information & technology services Larsen & Toubro, E&C Division Engineering & construction MindTree Ltd. Information & technology services Patni Computer Systems Information & technology services Reliance Industries Diversified industrials Tata Consultancy Services Information & technology services Tata Steel Metal fabrication Tech Mahindra Information & technology services Wipro Technologies Information & technology services Note: A total of 14 organizations were selected as 2009 Indian MAKE Finalists * Workshop on Measuring KM in Projects: Why, What and How (30th October, 2009) held at Bangalore: Many enterprises have been successful in instilling the culture and practice of KM across their organizations. In the initial years of KM, however, in spite of having made deep inroads into the organization, it continues to possess the character of an undifferentiated corporate. This is largely due to the nature of KM during this time where, in responding to its appeal for bridging islands of knowledge across the organization, the innate impulse of KM teams is to facilitate greater flows of relatively generic and more widely applicable knowledge than of highly context-bound and locally relevant knowledge. While the former significantly caters to long term knowledge needs of employees, the latter types of knowledge critical to the immediate needs of business - are not well developed in the supply chain thereby leading to a weakened perception of the value of KM. It may be recognized therefore that for a KM solution to be enduring, it inevitably has to draw its sustenance from the creative interplay between the local and the global, the specific and the generic, and the immediate and the long-term applicable forms of knowledge in the organization. The current focus of KM in many organizations is on two primary issues: how do we derive concrete business benefits from KM and how do we measure and demonstrate the benefits as returns on investment made in KM? The workshop addressed both of

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these issues by presenting a framework for adapting and fine-tuning generic KM practices in particular projects to generate concrete business benefits, as well as for measuring, analyzing and benchmarking critical KM parameters in projects.

KM @MECON * KM Article writing Competition- August 2009: The articles published in the 4th edition of KM Bulletin- August 2009 were ranked and Director (Engineering) awarded the winners with certificate of appreciation and a memento. We gladly announce the Best KM Contributors of August 2009: First Rank: Shri. S. K. Verma, AGM (Iron Making), MECON, Ranchi Second Rank: Shri. S. K. Bhattacharjee, AGM (Iron Making), MECON, Ranchi Third Rank: Shri. A. K. Agarwal, AGM (Iron Making), MECON, Ranchi Fourth Rank: Shri. Bikas Pandey, SDE (SMS), MECON, Ranchi uture editions

In response to the second competition in series of KM Article Writing Competitions, we received four articles on the topic of Journey of MECON in Oil & Gas Sector from MECON, Delhi. We are presenting the enriched articles of the following KM Contributors:

1. Shri. K. K. De, GM (Oil & Gas) (Page 6-31) 2. Shri. H. Chandnani, DGM (Civil) & Project Coordinator (Page 32-40) 3. Ms. Shalini singh, ADE (Iron Making) (Page 41-52) 4. Shri. R. K. Narayan, DGM (Oil & Gas) (Page 53-61)

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CONGRATULATIONS TO ALL THE WINNERS!!!

Wish you a valuable plunge into the ocean of knowledge presented in the form of articleshave a great reading time!!!


CNG AND CGD PROJECTS K. K. De, GM (Oil & Gas) MECON, Delhi Background: Rapid growth of Delhi after 60s resulted in significant increase in environmental pollution. During the 70s and 80s, the national capital, saw an unprecedented growth in population, vehicles and small-scale industries, which caused serious ecological imbalance and environmental degradation. This rapid growth of population along with an increase in vehicular population as well as industrialization and has resulted in an increase in the levels of various air pollutants, namely (1) Oxides of Sulphur, (2) Oxides of Nitrogen, (3) Suspended Particulate Matter, (4) Respirable Suspended Particulate Matter, (5) Carbon Monoxide, (6) Lead, (7) Ozone, (8) Benzene, (9) and Hydrocarbons. Based on the ambient air quality monitored by the Central Pollution Control Board in 1998, it was found that the contribution from vehicles to the ambient air pollution of Delhi is about 72% of the total pollution from other industries including thermal power plants and domestic sources. It was also noticed that there was a rising trend in sulphur-dioxide and Nox of about 25% per annum. Table- 1.1 and 1.2 indicates the contributions from various sectors to ambient air pollution. The contribution from the vehicular sector increased from 23% in the year 1970/ 71 to as much as 72% by the year 2001. Sources of Air Pollution Table : 1.1

Source 1970-71 1980-81 1990-91 2000-01 Industrial 56% 40% 29% 20%

Vehicular 23% 42% 64% 72% Domestic 21% 18% 7% 8%

About 72 % Of Total Air Pollution Comes From Transport Sector Sector-Wise Emissions In Delhi (Metric Tonnes Per Day) (Statistics of 2000-01) Table : 1.2

Pollutants Transport Power Industry Domestic Total

UHC 310 2 6 2 320

SPM 13 50 60 12 135

Nitrogen Oxides 157 143 20 3 323

Sulphur Dioxide 11 121 35 12 179

Carbon Monoxide 810 8 128 117 1063

Total 1301 324 249 146 2020

About 72 % of total air pollution comes from transport sector (SOURCE : CPCB)


On July 28, 1998, while hearing a Public Interest Litigation the Honble Supreme Court directed among other things, the replacement of all pre-1990 Auto rickashaws and retrofitting all the post 1990 auto rickshaws and taxis with devices running on clean fuels. In addition to this, the Honble Court also directed the withdrawal of buses which were more than eight years old and conversion of the rest of the citys bus fleet to CNG based vehicles and setting up of more CNG filling station. This was based on the recommendations of Environment Pollution (Prevention & Control) Authority (EPCA), also known as Bhure Lal Committee, set up by the Ministry of Environment & Forests. In late 2001, the Delhi Govt. prepared a phase out plan for diesel buses, which was approved by the Honble Supreme Court. Under this plan, 800 diesel buses per month were to be phased out every month between April, 2002 and November 2002. Following this plan, the entire public city bus fleet was converted to CNG for which, Govt. of Delhi provided adequate funds. Apart from buses, all pre 1990 auto rickshaws were also to be replaced with new auto rickshaws and post 1990 auto rickshaws were to be retrofitted with CNG kits. Worldwide, there are more than 10.5 million NGVs on the roads as of August 2009, with the largest number of NGVs in Pakistan, Argentina, Brazil, India, Italy and China, with South America leading with a global market share of 48%. At present there are about 3,00,000 CNG vehicles in NCT of Delhi, including about 13,000 CNG buses, about 4,000 CNG RTVs, about 1,70,000 CNG private cars, 30,000 CNG taxis and about 90,000 CNG autos (3-wheelers). With CNG accepted as an alternative clean fuel, another 16 states including the bordering states of Delhi were set for making CNG network as per the recommendation of Bhure lal Committee. CNG is also the cheapest of auto fuels, as per prevailing prices on date. MECON in CNG and CGD Projects: In July 1999, M/s Indraprastha Gas Limited, (a Joint venture company of GAIL, BPCL and Delhi Govt.) appointed MECON as their Project Management consultant (PMC) to set up CNG and City gas distribution network in NCT of Delhi for Phase I (to meet the deadline set by the Honble Supreme Court) and later (in 2001), for expansion of CNG and City gas distribution network further in NCT of Delhi under Phase II. After successful completion of expansion programme of CNG and City gas distribution network in Delhi, MECON has also completed CNG distribution network in another 7 cities (namely, Ahmedabad, Vijayawada, Agartala, Lucknow, Agra, Grearer Noida and Pune) as PMC. Presently, MECON is executing fresh PMC contracts for CNG and City gas distribution (CGD) project (including expansion programme) for six cities, namely, Pune, Lucknow, Agra, Hyderabad, Kakinada and Agartala. In this article, a brief overview of CNG and CGD project has been presented. About CNG and its advantages over other available fuels : CNG is nothing but the natural gas in compressed form. Natural Gas is basically a mixture of hydrocarbons consisting of approximately 80 to 90 percent methane in gaseous form. Due to its low energy density, it is compressed to a pressure of 200 to 250 Kg/cm2 (to enhance the vehicle on-board storage in a cylinder) and hence the name Compressed Natural Gas. It is stored and distributed in Steel (now Aluminium/Composite/Metal-composite also) cylinders at a normal pressure of 200220 bar (29003200 psi). CNG's volumetric energy density is estimated to be 42% of LNG's (liquefied natural gas), and 25% of diesel's. Natural Gas is colourless, odourless, non-toxic but inflammable and lighter than air. CNG is not a liquid fuel and is not the same as LPG (liquefied Petroleum Gas), which consists of propane and butane in liquid form. Natural gas is normally transported from the source upto the users by pipelines. The typical composition and physical properties of CNG (i.e. Compressed Natural Gas) is as follows: Typical Composition of CNG: Table : 1.3 Methane 88%


Ethane 5%

Propane 1%

CO 5%

Others 1%

Total 100%

Note: As per the notification of Central Pollution Control Board (CPCB), Methane content in

Compressed Natural Gas to be used shall not be less than 87%. Physical Properties of CNG: Non-toxic Natural gas being lead/sulphur free, its use substantially reduces harmful engine emissions. When natural gas burns completely, it gives out carbon dioxide and water vapour - the very components we give out while breathing! Lighter than air Natural gas being lighter than air, will rise above ground level and disperse in the atmosphere, in the case of a leakage. Colourless Natural Gas is available in the gaseous state, and is colourless. Odourless The gas in its natural form is odourless, however, ethyl mercaptan is later added as odorant so as to detect its leakage. Technology in CNG cars: Any existing petrol vehicle can be converted to a bi-fuel (petrol/CNG) vehicle. Authorized shops can do the retrofitting. This involves installing a CNG cylinder in the trunk/boot, installing a CNG injection system and the electronics. CNG cylinders can be made of steel or aluminum. The equipment required for CNG to be delivered to an Otto-cycle engine includes a pressure regulator (a device that converts the natural gas from storage pressure to metering pressure) and a gas mixer or gas injectors (fuel metering devices). Earlier-generation CNG conversion kits featured venturi-type gas mixers that metered fuel using the Venturi effect. Often assisting the gas mixer was a metering valve actuated by a stepper motor relying on feedback from an exhaust gas oxygen sensor. Newer CNG conversion kits feature electronic multi-point gas injection, similar to petrol injection systems found in present generation cars. However, a suitably designed natural gas engine may have a higher output compared with a petrol engine because the octane number of natural gas is higher than that of petrol as this would allow for an engine design with a higher compression ratio. CNG compared to LNG: CNG is often confused with liquefied natural gas (LNG). While both are stored forms of natural gas, the key difference is that CNG is in compressed form, while LNG is in liquefied form. CNG has a lower cost of production and storage compared to LNG as it does not require an expensive cooling process and cryogenic tanks. However, CNG requires a much larger volume to store the same mass of gasoline or petrol and the use of very high pressures (3200 to 3600 psi, or 220 to 250 bar). Comparative Study of CNG Properties w.r.t. other automotive fuel and its Safety Aspect: The properties of unleaded petrol, diesel, LPG and CNG are as mentioned in the table-1.4 Comparative Properties of available Fuels Table : 1.4


PROPERTIES UNIT PETROL DIESEL LPG CNG

Relative Density WATER=1 0.74 0.84 0.55 -

Relative Density AIR=1 - - 1.285 0.64

Auto Ignition temperature C 360 280 374 580

Flammability Range % IN AIR 1-8 0.6-5.5 2.2-9.0 5-15

Flame Temperature C 2030 1780 1983 1900

Octane No. - 87 - 93 127

Conclusion : CNG is a safe fuel with better combustion quality The data indicates that CNG is less likely to auto-ignite on hot surface than gasoline or diesel and requires high energy for ignition. In case of spillage of liquid fuel (LPG), which is heavier than air, the liquid tends to spread at ground level and burn at the surface, if catches fire. Natural gas is lighter than air, so in case of leakage, the gas will not accumulate at the ground but will disperse in the atmosphere. In case of fire, the gas will burn above ground level if combustible/explosive mixture (which contains natural gas in the range of 5-15% only by volume) is formed. CNG Emissions: A comparative table of emission measurements made by the apex institutes of India viz Automotive Research Association of India (ARAI), Vehicle Research & Development Establishment (VRDE) and Indian Institute of Petroleum (IIP) are as reproduced below. Reduction in Mass Emission with CNG retrofitted kits in Petrol Vehicles as Certified by ARAI/ VRDE in Gm/Km

Table : 1.5 Type of Vehicle Pollutant Petrol CNG % Reduction

CO 19.79 0.55 97 Maruti Omni

HC 1.14 1.02 11

CO 4.94 0.59 88 Maruti Gypsy

HC 1.86 1.42 24

CO 18.38 0.94 95 Premier Padmini

HC 2.83 2.03 28

CO 15.60 2.04 87 Premier 118 NE

HC 2.57 1.92 25

CO 52.16 0.78 98 Ambassador

HC 6.37 4.33 32

HC 3.26 1.26 63.19

CO 5.48 1.57 71.35

CO 47.44 27.60 41.82

Bajaj three wheeler

Nox 0.25 0.20 20.00

Conclusion : CNG is the cleanest fuel operating today * As per the notification of Ministry of Surface Transport (MoST), Methane content in Compressed Natural Gas to be used shall not be less than 80%.


Advantages of CNG over other alternative fuels: i) CNG is the cleanest burning fuel operating today The vehicles converted to CNG produce little or no emissions. CNG Yields compared to Petrol 99% less CO; 52% less hydrocarbons; 36% less NOx; 100% less SOx; 100% less particles CNG is the safest fuel operating today. CNG is less likely to auto-ignite on hot surfaces, since it has a high auto-ignition temperature (540 degrees centigrade) and a narrow range (5%-15%) of inflammability. It means that if CNG concentration in the air is below 5% or above 15%, it will not burn. This high ignition temperature and limited flammability range makes it an inherently safe fuel. In the event of a spill, it poses no threat to land or water. CNG also disperse rapidly, minimising the ignition risk compared to petrol or diesel. iii) CNG has better combustion quality than any other motor fuel. CNG has much higher octane number which makes it a good alternative for spark ignition engine. CNG driven vehicles' acceleration speed is greater than that of petrol or diesel vehicles. Moreover due to cleaner burning characteristic of natural gas, CNG vehicle engines will run more efficiently, thereby enhancing the life of the vehicle. iv) CNG is the most economical fuel operating today On energy equivalent basis, CNG cost approximately 1/3 the cost of gasoline in India. This means that the operational cost of vehicles running on CNG, as compared to those running on other fuels, is significantly low at the prevailing price of fuel in India. Operational cost of CNG vehicles in India is 68% lower than petrol and 36% lower than diesel. v) CNG mixes evenly in air Being a gaseous fuel CNG mixes in the air easily and evenly. Being non-corrosive, it enhances the longevity of spark plugs. Methodology Adopted for CNG Distribution: As already stated earlier that CNG (Compressed Natural Gas) is nothing but the natural gas in compressed form. Due to low energy density of Natural gas, it is compressed to around 250 Bars for automobile use so as to facilitate increased onboard storage in the vehicles. Presently, CNG dispensing in Delhi is done through four types of CNG stations namely, Mother stations, On-line stations, Daughter station and Daughter Booster station. A brief technical description of each type of station is presented below. The choice of different types of CNG station at a location is primarily guided by cost of laying the steel pipeline upto the station connecting the natural gas supply source, the requirement of CNG quantity and the types of vehicles (ie, no.of buses /cars/3 wheelers to be filled.


Fig : 1.1 Schematic Diagram of Methodology Adopted for CNG Distribution Mother Stations: Mother stations are installed on the pipeline route and are connected to the natural gas pipeline for its continuous supply. On these stations, reciprocating compressors of capacity 1200 SCM/hr. at suction (inlet) pressure 17-19 kg/cm2(g) and discharge (outlet) pressure of 250 kg/cm2(g) are installed taking gas from pipeline. The Prime movers of these compressors are either a Gas Engine or an Electric motor. However, except in Mumbai, most of the these compressors are normally Gas Engine driven. Stationary storage cascades (as many as the number of compressors) are installed for smooth functioning of station. They also act as buffer for CNG supply as well as for the purpose of banking as per need. Exact number and capacity of compressors, cascades and dispensers depends upon the requirement and demand of CNG at these stations. Direct retailing/ dispensing are done to different types of vehicles both car/autos and buses as per requirement. As the name suggests, a mother station also feeds the daughter stations by way of supplying CNG through mobile cascades (usually of 2200 water litre capacity each). Normally each mother station has at least one filling point for filling of mobile cascades.


Fig : 1.2 Schematic Diagram of a CNG Mother Station On-line Stations - Online stations are also installed on the pipeline route and are connected to the natural gas pipeline for its continuous supply. These stations are similar to the Mother stations except that the facility of Mobile cascade filling is not provided at these stations. On these stations, generally compressors with capacity of 550/600/750 SCM/hour and discharge pressure of around 255 kg/cm2g are installed taking gas from pipeline. These compressors are normally Electric Motor driven (because of comparatively low power consumption), although gas engine driven on line compressors also exist. Number and capacity of compressor, cascade and dispenser depends upon the available suction pressure and requirement/demand of CNG at the on line station.

Fig : 1.3 Schemati

c Diagram

of a CNG

On Line station

Daughter Station - These are the stations where natural gas pipeline is not available, At these stations, CNG is transported through cascades (Bundle of Cylinders) normally of 2200 water litre capacity fixed on light commercial vehicles (LCV). These cascades are called mobile cascades which are filled at Mother Stations. At daughter stations, CNG is dispensed to vehicles on pressure equilibrium principle. After few fills of the CNG vehicles, the pressure in the cascade placed at daughter station gets reduced resulting in lesser quantity of CNG fills to the subsequent CNG consumers due to low pressure in the cascade leading to general customer dissatisfaction. It may be noted that at a daughter station, the CNG supply is made available only through mobile cascades. Dispensing CNG from a daughter station generally incurs higher cost but is the only option where there is no pipeline connectivity to source Natural Gas. Daughter Booster Station - These are also the stations, where natural gas pipeline is not available like daughter stations. The only difference between daughter station and daughter booster station is that, a Booster Compressor is installed in-between the mobile cascade and the dispenser. The function of the Booster Compressor is to draw the gas from the mobile cascade right from 180 kg/cm2 pressures to as low as 30 kg/cm2 pressure and boost it to 200-220 kg/cm2 before it is fed to CNG vehicles . Installation of booster compressor helps in higher cascade capacity utilization and increased customer satisfaction. This also helps in evacuating the mobile to a larger extent resulting in less cascade movement on road.


Schematic Diagram of a CNG Daughter Booster Station Mega CNG Stations: Mega CNG stations have been conceptualised to cater to a large fleet of vehicles, particularly the buses. The objective is to provide comfortable filling experience to the consumers when they come to the station for refueling. Mega CNG stations are constructed on much larger plot of land than that of conventional CNG Mother stations, as a result of which more number of Compressors and Dispensers are installed and more number of vehicles are simultaneously refuelled at such stations. A number of Mega CNG stations have been commissioned in Delhi (at Rohini, Sector 23, Patparganj and Sarai Kale Khan in 2003). The Mega CNG station at Patpargang, East Delhi, can simultaneously refuel five buses and eight other vehicles (cars, autos, mini buses etc.). Built on a plot of size 75 m X 40 m, it has the capacity to comfortably refuel CNG to 800 buses and over 1500 other vehicles daily. A Mega CNG station at Chinchwad, Pune, (built in 2007) can simultaneously refuel four buses and sixteen other vehicles (cars, autos, mini buses etc.). It has the capacity to comfortably refuel CNG to 600 buses and over 3000 other vehicles daily. Components of CNG Network: Main Pipeline/Gridline (underground) network from CGS (City Gate Station) including Spur lines (branch lines from Main Gridline through tap offs) upto the CNG stations. These are 3 layer PE coated CS pipes Odorising system Sectionalizing Valve Stations, CS Ball/Globe/Gate Valves as per requirement & other piping components, regulating station equipment, etc. Station Piping & SS Tubing for high pressure gas at CNG stations. CNG Compressors, Cascades & Dispensers CNG Stations. All the above components are briefly discussed below: About City Gate Station (CGS) : It is the entry point of Natural Gas from a sub-transmission high-pressure gas pipeline to a City, hence the name Components of City Gate Station (CGS) : Inlet & Outlet isolation valves Knock Out Drum (KOD) Filter (Cartritge) Metering Unit (Turbine / Orifice / Ultrasonic) Gas Chromatograph (GC)


Pre-heater (if required) Pressure reduction skid comprising Active & monitor combination with a minimum 50% redundancy Stream discrimination arrangement Slam shut valve for over & under pressure protection Creep relief valves. Odorising Unit

A City Gate Station (CGS) About Steel Pipeline: Steel Pipeline Design Parameters : Max. Op. Pressure, kg/cm2(g) : 19 kg/cm2 (g) or 24 kg/cm2 (g) (as desired by client) Op. Temperature, C : 5-50 Design Temperature : Buried 45C Above Ground 65C Population Density Factor : 0.4 (Class IV) Design Life : 30 Years Corrosion Allowance : 0.5 mm for buried pipeline; 1.5 mm for A/G station piping Pipeline Efficiency/ Roughness : 0.9 / 45 micron. The sizes of pipes are finalized after carrying out simulations and sizing calculations based on peak load as per market survey data. A minimum thickness of 6.4 mm is kept as per guideline of PNGRB. Selection of Steel Pipes : Table : 1.6

Pipe size Standards & Codes Grade Wall Thickness (mm) for 300# Manufacturing Process


2 ASTM A106 Grade B Sch 80, 5.5 Seamless

4 API 5L Grade B 6.4 ERW / Seamless



10 API 5L Grade B As per calculation, but min. 6.4 ERW / Seamless

12 API 5L Grade B As per calculation, but min. 6.4 ERW / Seamless

16 API 5L Grade B/X42

As per calculation, but min. 6.4 LSAW / HSAW

18 API 5L Grade X42/X52

As per calculation, but min. 6.4 LSAW / HSAW

Insulation Joints : Insulating joints are provided at transition point of aboveground & underground portion of pipeline and at tap-off points for electrical isolation. These will be mono-block type suitable for both above/ underground installation. Pipeline External Corrosion Protection : Three-layers of PE Coating are provided for the pipeline. Temporary Cathodic Protection are provided to take care during construction period. Impressed Current based Permanent Cathodic Protection System are provided. Anode bed is designed for a service life of 35 years. About Odorising system : Natural gas is odorless. For safety reasons, odorant must be added to natural gas in order to detect leaks in natural gas systems. Typically, odorant is transferred from an odorant storage chamber to natural gas flowing in a gas line. The odorant commonly used is Ethyl Mercaptan. Operating Principle: Programmable Pressure Injection System / Automatic dozing system with solenoid operated pumps and Pneumatic Panel with Cabinet & Electronic Control unit. For the Odorizer auto mode operation, flow signal is provided in form of analogue 4-20 mA serial communication data inputs/ pulse from flow computer/ metering device. Therefore, the Electronic Control unit of Automatic dozing system should be able to accept two nos. of 4-20 mA signals/serial inputs corresponding to flow rates of of each flow computers of dual stream metering system. About Sectionalizing Valve Stations : Sectionalising valve stations are installed at approximately every 2.5-3 km (to stop the supply of gas through these valves in case of any accident and also to facilitate tap offs, both hot and cold). Venting provision are kept at approximately every 5-6 Km by way of providing a vent pipe of min. 3m height above ground and located at a safe distance from the valve assembly. All Main line sectionalising valves are full bore ball valve with extended stem. 4 dia. Tap-offs are also provided at these locations for city gas distribution. About Ball Valves : Selection criteria of Ball Valves: Summarised in table 1.7 Table : 1.7

Size

Code End Connections Mounting type


Less than 2 BS 5351 Butt Welded / Flanged Ends Floating

2 to 6(150#) API 6D Butt Welded Ends / Flanged Ends Floating

8 andabove(150#)

API 6D Butt Welded Ends / Flanged Ends Trunnion

2 to 4(300#) API 6D Butt Welded Ends / Flanged Ends Floating

6 andabove(300#)

API 6D Butt Welded Ends / Flanged Ends Trunnion

Both 150 and 300 class ball valve is used based upon the operating pressure class. The maximum distance between two isolation valves is restricted to 3 km. Important Features of Ball valves: Fire Safe design: As per API 607/ 6FA. If soft seal is used in design / construction. Double Block and Bleed: To facilitate complete flush, drain and venting of the valve body cavity Anti static design: Anti Blow-out Design: The stem is designed with integral T-type shoulder to provide blow-out proof effectively. Selection Criteria of CNG Compressors and Dispensers in CNG Stations: The major equipment (i.e. compressors and dispensers) in CNG Mother and On Line stations are selected based on dispensing capacities and corresponding compression capacities of these stations at peak load. The dispensing capacities of these stations at peak load are generally considered as per market survey data or as given by client. The basis of selection of compressors and dispensers is explained in the following table. Table : 1.8 Selection of CNG Compressors and Dispensers in Mega Station at Chinchwad at peak load

Dispensing capacity at peak load No. of dispensers

No. of vehicles

Load Unit

Compression capacity: 1:1.5 Gas Density : 0.8 Kg/SCM

200 Buses/ day @ 80 kg/ bus

= 16000 kg/ day

Compression capacity : 45000 Kg/day : 56250 SCMD

No. of Compressors

500 Cars/ day @ 5 kg/ car

= 2500 kg/ day

Capacity of 2x1200 SCMH (with 18 hrs. running) =

43200

SCMD

500 Autos/ day @ 2 kg/ auto

= 1000 kg/ day

Capacity of 1x750 SCMH (with 18 hrs. running) =

13500

SCMD

30 LCVs (2200 WL) @ 350 kg/ LCV

=

10500 (Equivalent to 5250 autos)

kg/ day

Capacity of (2x1200+1x750) SCMH =

56700

SCMD

2x1200 + 1x750 SCMH

Total = 30000 kg/ day

3 Bus + 3 Car

Note: Compression capacity is met.

About CNG Compressor packages: Components of CNG Compressor packages: Gas compressor Prime mover Drive assembly


Pressure vessel Piping (sizes and routine), Valves and fitting Air exchanger (Heat exchanger) Common base frame Acoustic enclosure Electric control panel with PLC Internal Electrical devices Safety features. Gas compressors: These are reciprocating compressors (due to low/medium volume and high pressure). Number of stages is decided on the basis of compression ratio (Discharge pressure/ Suction pressure) & rise in temperature in each stage. Prime mover: It may either be a Gas engine or an Electric motor whose power is decided based on the BKW of compressor at design condition plus auxiliary power (of heat exchanger) with 10% extra. Drive assembly: It may either be direct drive coupling or Belt drive. However, if the driver speed is more than 1500 rpm, direct drive is preferable (due to less transmission loss). Pressure vessel: Sizing as per API after conducting Pulsation analysis as per API-618 approach-3. Mechanical design as per ASME Sec VIII. Internal Piping (Mechanical design):. Sizing as as per Pulsation analysis. Mechanical design as per ASME Sec VIII. Acoustic enclosure: The adequacy of size of enclosure and thickness of mineral wool shall be so decided as to reduce the overall noise level to 70 dbA at 1 meter distance from the enclosure. Electric control panel with PLC: The control panel shall be flame proof with area classification mentioned in the Technical specification. The most important in the PLC is that the flow chart, the logic write up and the operation philosophy shall be so created that the software is operator friendly and suitable for smooth operation of the entire package. Electrical devices: All Electrical devices shall meet the requirement for the area classification specified in the Technical Specification. Safety Features for Compressor package: Emergency shut down (ESD) system in control room Fail safe system incorporated to stop compressor, isolate cascade, dispenser & compressor suction line, ground ignition and cut off fuel gas supply to engine on activation of ESD switch Anti-static anti-fire type drive belt Two L.E.L detectors and two Ultra Violet (UV) flame detectors for compressor enclosure Instrumentation to prevent air-ingress in the system during start up, operation and shut down PSV, NRV, IV, solenoid valves, probes for sensing temperature and pressure Proper earthing of Compressor and Prime mover Twin cylinder configuration, automatic CO2 flooding system to effectively cover the entire enclosure (one CO2 cylinder inline and second standby) Hoses, junction boxes, tubes made of plastic / rubber prohibited inside enclosure Maximum vibration level at cylinder limited to 7.5 mm/s Acoustic enclosure to restrict noise level below 70 dB(A) with flame proof lighting with proper ventilation Alarms and Trips for Compressors: Low lubricating oil pressure Low lubricating oil level Lubrication failure High discharge temperature at each stage


High discharge Pressure at each stage Low suction pressure High suction pressure High BDV pressure High vibration Alarms and Trips for Gas engine: Low oil pressure Low oil level High oil temperature No coolant flow High coolant temperature Low coolant level Engine over speed Engine over load High vibration Gas detection (LEL) Flame detection (UV) ESD Failure of forced ventilation system About CNG Dispensers: Type and basic features of CNG Dispensers

Type of Dispenser

Type of Flow Hi / Low flow

Flow rate Kgs/min

Fill Pressure kg/cm2 (g)

Fill Hoses Nos. per Dispenser

Remarks

Bus Hi 75 200 1(Single)

Car Hi/Low 15 200 2 (Two) Inlet Pressure 250 Kg / cm2(g)

Components of CNG Dispensers Mass Flow Meter Coalescent filter Solenoid Sequencing Valves Dispenser Cabinet Fill Hose & Fill Nozzle Snap-tite Break-away (coupling) Electronics and Display unit Mass Flow Meter : Coriollis Type Mass Flow Meter with Integral Display Unit should be provided to ensure accuracy and direct Mass Flow measurement which shall conform to AGA 11 standard and approved for custody transfer metering of CNG at each of the refueling hose. Coalescent filter : Coalescent filter is provided at inlet of bank supply line with manual drain valve to ensure that the oil carryover in the CNG being filled to Vehicle is < 5 PPM. Solenoid Sequencing Valves : 1 Solenoid Valve for single arm bus dispensers (Single Bank fill system) and 6 Solenoid Valves for twin arm car dispensers (for 3 Bank Sequencing System for Car). Solenoid Valves are air actuated and not gas actuated. Dispenser Cabinet: Complete cabinet shall be of Stainless Steel (SS-304) with tamper proof locking arrangement. However, powder coated cold rolled steel cabinets are also being used in this industry. Fill Hose & Fill Nozzle : Fill hose should be electrically conductive hose meeting the requirement of NFPA-52 and NGV 4.2. Fill hose shall have Sherex CT-5000 Nozzle or equivalent suitable to fill bus or NGV 1 Type 2 Class A suitable to fill Car.


Dispenser Electronics and Display unit : The Dispenser Electronics shall be Microprocessor based and inbuilt with the dispenser. All the electronic cards shall be located in flameproof boxes inside the dispenser cabinet. The display unit shall be electronic type and display the following key information on the dispenser with liquid crystal back-lit display for night viewing showing: Quantities of gas dispensed in kg (4 digits in 2 decimal points i.e., 00.00) in one row. Unit cost of gas dispensed in Rupees, Rs/kg (4 digits in 2 decimal points i.e., 00.00) Complete transaction value in Rs (6 digits in 2 decimal points i.e., 0000.00) in one row. There should be 4 displays, two on each side of the car dispenser. There should be 2 displays, one on each side of the bus dispenser. Displays must remains active for at least 15 minutes after power failure. Data Recorder : The dispenser shall have an inbuilt Automatic Refueling Data Recorder unit for the each independent refueling line. The dispenser system should be capable of storing up to 1,250 refueling transactions data with date & time which can be downloaded frequently into another portable computer with compatible Microsoft software. Safety Features for Dispensers: Designed for hazardous area : Class-1, Division-1, Group-D Break-away coupling Dispenser automatically and immediately shuts-off CNG supply to fill individually in case of power failure, loss of display, failure of metering low flow, overfill Overfill protection through electronically programmed hose to terminate the fill after 200 kg/cm2(g). Pressure relief valve provided to avoid overfilling About CNG Cascades: Type and configuration of CNG Cascades generally used in India: Type/Nomenclature of Cascade

Flow Sequencing System

Configuration of Cascades

Fill Pressure kg/cm2 (g)

approx weight of CNG contained in each type of cascade

Overall dimension of cascade frame (B x H x L) in mm and approx empty weight of cascade.(Refer note below)

4500 WL Stationary for Bus (WL- Water Liter)

Single Bank fill system

47 nos. cylinders 100 WL each Or 62 nos. cylinders 75 WL each

250 580 Kg 1800x1600x 5600 8800 kg

3000 WL Stationary for bus

Single Bank fill system


250 380 Kg 1800x1600x 3800 5400 kg

3000 WL Stationary for car or bus and car combined

3 Bank (Hi/Medium/Low) sequencing fill system


250 380 Kg 1800x1600x 3800 5400 kg

2200 WL Stationary for car (in Daughter Booster station)

3 Bank (Hi/Medium/Low) sequencing fill system

23 nos. cylinders 100 WL each Or 31 nos. cylinders 75 WL each Or 46 nos. cylinders 50 WL each

220-250 280 Kg 1200x1600x 2800 4300 kg

2200 WL Mobile for car

2 Bank (Hi/Low) sequencing system


220-250 280 Kg 1200x1600x 2800 4300 kg


Note: Dimensions B & H are fixed as per technical specification, while, only L shall may vary depending on the configuration of cascade as well as the design of manufacturer/supplier of cascade. Components of CNG Cascades: Cascade Frame: Structure are designed for 4G impact test. CNG cylinders: Approved by Chief Controller of Explosives (CCoE) Piping manifold with flow components: All SS tubes, fittings, Inter connecting valves, safety relief valves and check valves shall be of approved make. Safety Features for Cascades : Cylinder material is seamless alloy steel (Cr-Mo) and approved by Chief Controller of Explosives (CCoE) Fusible burst disc (IS:3224) will rupture at 280 kg/cm2 pressure Cascade frame structure designed for 4G impact test. About CNG Stations: Design aspects of CNG station : Position / Location of CNG compressors: This is guided by OISD 179 (Safety requirements for compression, storage, handling and refueling of CNG for use in automotive sector). However, the inter distance between two successive compressors is generally kept as 3.0 m for safe operation of doors. Position / Location of CNG Dispenser island: Guided by OISD 179; however, the requirement of local (state) authorities (like Municipal corporation, PWD etc.) are also taken care of. Position / Location of Stationary cascades: Guided by OISD 179; however, these are also placed over roof of Utility building to save costly ground space. Location of LCV filling stand (ie, Mobile cascade): Guided by OISD 179; however, it shall be so decided as to minimize interference with regular traffic. LCV stand shall also be designed in such a way that the LCV does not take a reverse turn after filling (for safety reason).


Position / Location of Utility building, Sales building and Transformer room (substation): The edge of Utility building cum Sales building (or, both Utility building and Sales building if they are separate) should be at least 6.0m away from the dispenser. The Transformer room / Di-pole structure shall be at least 12.0 m away from the compressor as well as dispenser (for safety reason). Canopy for dispensers: Height is generally 5.5 m from finished forecourt although, canopies of height 3.5 m exclusively for 3- wheelers also exist. Projection of canopy shall be 4.0 m (minimum) all around from the dispenser for canopy height 5.5 m (from forecourt level) and 3.0 m all around from dispenser for canopy height 3.5 m (from forecourt level). The structural design of canopy shall meet the 3-S criteria (ie, strength, stability and serviceability) for most adverse loading combination. High pressure SS tubing trench: Route of tubing trench shall be so selected as to minimize the length of trench and tubes. Proper slope and provision for storm water drainage system inside the trench shall be kept while designing the trench. This is also to be ensured during construction. Station piping (above ground): While designing the piping manifold, including hook up of compressors, aesthetics shall also be taken into consideration apart from technical requirement. Clear and safe passages for vehicles from ingress and egress to dispenser Safe turning radius for vehicles and parking during filling. Safety fencing to equipment area and safety guards around dispenser island; proper slopes, oil catch pits and quick drainage system. Proper slope and adequate drainage system for forecourt. Electrical installations: Shall be designed as per provisions of OISD 179. Care shall be taken to ensure that the area lighting fixtures in the vicinity (within 6.0 m) of CNG equipment and LCV filling area are flameproof. Canopy lighting fixtures and electrical installations within the canopy ceiling need not be flame proof provided there is air tight false ceiling all around the canopy u/s including the canopy facia. In case the u/s of canopy is not covered with false ceiling, (as in the case of some MS/OLS constructed within the Bus depot with existing canopy) the existing lighting fixtures and all electrical installations must be replaced with flame proof installations. Earthing pits: Shall be designed as per provisions of OISD 179. Number and location of Earthing pits (both Electrical and Instrumentation) shall be so selected that they meet the safety requirement of the equipment and the electrical installations within the station (as per guidelines of Chief Controller of Explosive).There shall be minimum two electrical earthings for each compressor, one electrical & one instrumentation earthing for each dispenser, one electrical earthing for each cascade and LCV stand apart from earthing of other electrical installations. Position / Location of Fire Safety Equipment: Shall be installed as per guidelines of Chief Controller of Explosive for CNG equipment. Traffic signs for CNG vehicles: Also called as direction signs are mandatory before commissioning. Safety signs: Following safety signs (minimum) are mandatory in each CNG station before commissioning. i) NO SMOKING sign. Ii) STOP VEHICLE sign. NO OPEN FLAME PERMITTED sign.


iv) FLAMABLE GAS sign. v) Sign showing DETAILED PRECAUTIONS & PROCEDURE DURING REFUELLING Environment friendly design with adequate green turfing Rain water harvesting system Aesthetics- the last but not the least. Components of CGD (City Gas Distribution) / PNG (Piped Natural Gas) Network: Main Pipeline/Gridline (underground) network from CGS (City Gate Station) including Spur lines (branch lines from Main Gridline through tap offs) upto the DRS. Odorising Unit (in CGS or immediately after CGS (before entering DRS). District Regulating Station (DRS) Medium pressure (upto 6 bar (g)) MDPE pipeline network after DRS to connect Domestic, Commercial and Industrial consumers. Metering and Regulating Station (MRS) for Industrial consumers. Pressure Regulators at downstream of Medium pressure MDPE pipeline (at 4 - 6 bar (g)) to low pressure (300 mbar for commercials & 100 mbar for domestic) PE pipes before entering Domestic and Commercial consumers premises. Installation of low pressure underground PE pipes outside the premises and above ground GI pipes along the outer walls of premises (for both Commercials and Domestic consumers) Diaphragm type Gas Meters for both Domestic and medium/ small Commercial consumers. i) Copper tubing (at 21 mbar pressure) within kitchen of premises. Except for (a) & (b) which have already been discussed earlier, the rest of the components are briefly discussed below.

City Gate Station

19 Bar Steel Network

6 Bar (PE pipe)

CNG Station DRS

GI Installation Service RegulatorDomestic Kitchen

100 mbar (PE pipe)

21 mbar (Copper

pipe)


Typical site installation of a DRS About District Regulating Station (DRS) : DRSs are installed at various strategic locations in the network to supply PNG to domestic, commercial and industrial consumers Twin stream regulating system with hot stand-by stream Regulating from inlet pressure of 19 kg/cm2 (g) pressure to outlet pressure range 1.5 - 6 kg/cm2 (g) Downstream Distribution via PE pipeline DRS components: Inlet & Outlet isolation valves Filter Active and Monitor Pressure regulators with a built in slam - shut device Independent slam shut valve Relief valve About Metering and Regulating Station (MRS) : MRS are used to supply gas to Industrial & large Commercial consumers requiring gas at 1-2 bar(g). Designed for Single Stream / Twin stream regulating and metering system as per requirement of client. Inlet pressure range : So as to ensure differential pressure of 1 bar (g) between inlet & outlet. Outlet pressure : 0.5 2.0 bar(g), depending on the requirement of customer. MRS components: Inlet & Outlet isolation valves Filter Pressure regulator with a built in slam shut device Relief valve Strainer


Flow Meter (RPD/ Turbine, etc.)

Single Stream MRS Dual Stream MRS About Pressure Regulators : Technical requirement of Pressure Regulators used for domestic and medium/ small commercial customers: Maximum Inlet Pressure: Maximum upto 4- 6 bar (g) as per design of Network. Nominal Outlet Pressure: 100 mbar (g) for domestic & 300 mbar (g) for commercials. Flow capacities: 10, 25, 40, 65 SCMH. End connections: Threaded (& Tapered) as per BS 21 Operating ambient temperature: up to 45 0C Lockup: Maximum pressure under no-flow condition. Creep relief valve: To protect against downstream over pressure at low flows or in the event of valve seat malfunction. Over Pressure Shut Off (OPSO): Device to protect against downstream over pressure. Under Pressure Shut Off (UPSO): Device to protect against downstream under pressure. Information required to select a regulator: Maximum and Minimum inlet pressure Required outlet pressure Maximum flow rate Tolerance on outlet pressure Size of pipe network at downstream of regulator. Type of gas Safety features required Size of orifice OPSO, UPSO & Relief settings Installation of indoors & outdoors Orientation of regulator About Gas Meters:


The most commonly used Gas Meters in CGD (or PNG) include Diaphragm Meters Rotary Positive Displacement (RPD) Meters Turbine Meters Diaphragm Gas Meters (for Domestic consumers) Tech Spec: EN 1359 Capacity: 2.5 m3/hr Rangeability or TD ratio: 1:150 or better Nominal Working Pressure: 21 mbar (g) End Connections: , as per BS 746 (Male) Diaphragm Gas Meters (for medium and small Commercial consumers) 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)/ 300 mbar (g) Rotary Positive Displacement (RPD) meters (for large Commercial and small industrial consumers) Tech Spec: EN 12480 Volumetric metering 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 Turbine meter (For Industrial Consumers) Tech Spec: EN 12261 Inferential meter Sensitive to gas velocity rather than volume flow High Pressure steady loads Typical Turndown 15:1 2% Q min to Qt 1% Qt to Qmax Sensitive against disturbances Sensitive against fast load changes About Medium Density Poly Ethylene (MDPE) Pipes: Tech Spec: ISO 4437 / BIS 14885


Material Grade & Color: Internationally approved resins of Yellow color for PE 80 grade & of Orange color for PE 100 grade Minimum Required Strength (MRS): 8 MPa for PE 80 grade pipe & 10 MPa for PE 100 grade pipe Pressure Class: SDR 11 (dia 20, 63, 90, 125 and 180 mm). Operating pressure: 4 bar (g) for PE 80 grade pipe & 7 bar (g) for PE 100 grade pipe Operating temperature range: - 10 0 C to + 40 0 C. Density Range 930 to 940 kg / m3

Tensile strength at yield elongation: 15 MPa. Elongation at break: More than 350% up to pipe size upto 125 mm, 500% for pipe sizes more than 125 mm 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, 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 80 or PE 100 Terminal pin size: 4 or 4.7 mm Voltage: 39 40 Volts. Color: Yellow / Black. PE Stop Off Valves (Typical): Standard: ASME B 16.40, EN 1555-4 Pressure Class: SDR 11. Operating Pressure: 4 / 7bar (g) for PE 80 / 100 Grade respectively 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. Valve Design: One piece construction. Ball position Indicator: Open / Close available. Crimping Fitting (Typical specification):


Used to connect u/g PE pipes with a/g GI pipes Operating Pressure: up to 4 / 7bar (g) for PE 80 / 100 Grade respectively. Operating Temperature: 40 0 C Hydrostatic Test Pressure: Minimum hold Pressure of 10 / 16 bar (g), for 1 hour duration for PE 80 / 100 Grade respectively. Pneumatic Test Pressure: Minimum pressure of 6 / 9 bar (g), for 1 hour duration for PE 80 / 100 Grade respectively. Pull out Test: Shall not fracture within the jointed assembly Shall withstand the Pneumatic pressure leak test Shall not leak GI ERW Pipes: Tech Spec: IS 1239 (Part 1) Types used: Heavy Class Material: IS 1387 Pipes shall be screwed with Taper threads Threads: Tapered and conforming to BS 21 / A1.20.1 Galvanizing: IS 4736 Coating requirements: Mass of coating is 400 gms / m2 Test Pressure: 5 MPa GI Fittings (Malleable Cast Iron): Tech Spec: IS 1879 Material: IS 2108 Grade BM 290 Dimensions: As per IS 1879 Threads: As per 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 :- 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 Typed 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 x BSPT (Female) Copper Tube: Used inside the kitchen of the domestic consumer Tech Spec: BS EN 1057 Size: 12 mm OD X 0.6 mm wall thickness Material: Grade Cu-DHP or CW024A Mechanical Properties: Ultimate Tensile strength: 235 MPa Elongation: 30% (minimum) Hardness: 53 to 80 on HV Scale Test Pressure: 1 bar (g) for a period of 2 minutes Bending Test: 900 & 1800 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 Lining: Synthetic rubber like Nitrile Butadiene Rubber (NBR) or Chloroprene Rubber (CR) Reinforcement: Wire reinforced in braided form in between the lining and the cover 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)


Piped Natural Gas (PNG) Distribution Network: Earlier (before inception of PNGRB) the PNG Distribution Networks (which originates from the downstream of DRS) were/ used to be designed for a maximum operating pressure upto 4 Kg/cm2(g). However, consequent to publication of PNGRB guidelines, MECON has started designing PNG Networks at a maximum operating pressure upto 7 Kg/cm2(g). Piped Natural Gas (PNG) Distribution Network for Medium/ small commercial consumers: In medium and small commercial connections (which comprise the Hotels, Restaurants, Malls etc.) the gas inlet pressure shall be regulated from 3- 4 Kg/cm2(g) or 6-7 Kg/cm2(g) (depending on the network design) to 300 milli-bars (0.3 bar) through a service regulator at the entry point to the Hotel / Restaurant/ Malls. It will be further supplied through MDPE and GI pipes upto the Kitchen of Hotel / Restaurant with individual meter (normally with Diaphragm Gas Meters) only. Piped Natural Gas Distribution Network for Domestic consumers: In Domestic connections (which comprises the large / medium housing complex) the gas inlet pressure shall be regulated from 3- 4 Kg/cm2(g) or 6-7 Kg/cm2(g) (depending on the network design) to 100 milli-bars (0.1 bar) through a service regulator at the entry point to the society / housing complex. It will be further supplied through MDPE and GI pipes upto the Kitchen of individual flats with individual meter and regulator assembly. In the Meter / regulator assembly of the individual flats the inlet pressure of the PNG shall be reduced from 100 milli-bars (0.1 bar) to 21 milli-bars (0.021 bar).


Typical Piped Natural Gas Distribution Network Codes & Standards for CNG Dispensers NFPA 52 : Standards for CNG Vehicular Fuel Systems NGV 4.1/ AGA 2-92: Requirements for CNG Dispensing Equipment for Vehicles NGV 4.2/ AGA 1-93: Requirement for Hoses for NGVs and Fuel Dispensers. ANSI / NGV1 : Compressed Natural Gas Fuelling Connection Devices. Standard for Fuelling Nozzles and Receptacles. NGV4 / AGA : Requirements for Breakaway Devices for CNG Vehicle Fuelling Dispensers and Fuelling Hoses. IS 5572 : Classification of Hazardous areas (other than Mines) for Electrical Installations IS 5571 : Guide for selection of Electrical Equipments for hazardous area OISD 179 : Safety requirements for Compression, Storage, Handling and Refuelling of CNG for use in Automotive Sector.


OISD 113 : Classification of areas for Electrical Installations at Hydrocarbon Processing and Handling facilities NFPA-52: 1992, ANSI, ASTM, NEC, NEMA, ASNZ, OIML, Indian Electricity Rules, Indian Explosives Act., Australian / New Zealand Refuelling Standard. AG901 / NZS 5425 The Standards of Weights and Measures Act 1976. The Standards of Weights and Measures (Enforcement) Act, 1985. The Consumer Protection Act, 1986. Codes & Standards for CNG Compressors : API-618 second edition NFPA-37, NFPA-52:1992: -Standards for CNG vehicular fuel systems NFPA-70: -Standard for electric devices & wiring OISD 179: -Safety requirements for compression, storage, handling and refueling of CNG for use in automotive sector Indian Electricity Rules, Indian Explosives Act Codes & Standards for CNG Cascades: NFPA 52 -Standards for CNG vehicular fuel systems OISD 179 -Safety requirements for compression, storage, handling and refueling of CNG for use in automotive sector Gas cylinder rules : 1981-Standards for CNG storage and gas cylinder rules Static and mobile pressure vessels (unfired ) rules, SMPV - 1981 CNG cylinder design code, IS : 7285 1988 IS:3224 1979 - CNG cylinder valves (amendments 1983, 84,85,86,89,92,98) IS:5844 1970- Hydrostatic stretch test IS:5903 -1970- Safety devices of gas cylinders Indian Explosives Act Australian / New Zealand refueling standard - AG901 / NZS 5425


MECONS GAINT LEAP IN TRENCHLESS ENGINEERING (A report on Indias longest HDD project)

Harish Chandnani, DGM (Civil) & Project Coordinator MECON Delhi MECON Delhi successfully executed a 2008m long HDD (Horizontal Directional Drilling) to cross MAHI River near Vadodara with a 12 NB carbon steel pipe string under restoration of natural gas supply project of GAIL from Dabka to Dhuvaran. The HDD which was completed on 23rd July 2008 was the longest ever Horizontal Directionally Drilled length undertaken by any HDD agency in India as on the date of completion. The pipeline has since been charged and gas-in has been successfully completed thereafter. This report gives a brief on Guided Boring & Directional Drilling, which is also known as the Horizontal Directional Drilling (HDD), which is ideal for the underground installation of gas, electric, water, telecommunication or soil remediation lines - without excavation or trenching. We shall subsequently give an insight on this unique HDD project which has been successfully got executed by MECON Delhi. A Brief on Horizontal Directional Drilling (HDD)

Introduction Trenchless Engineering is a branch of construction engineering dealing with techniques and related equipment used to develop, maintain and renew subsurface utility networks without excavating continuous trenches. It is a branch of applied engineering, which is State-of-Art, used to develop, manage, and renew continuous cabled and piped networks for transferring signals and fluids respectively. Major applications of these techniques are for Water Supply, Rainwater Disposal, Sewer Disposal, Natural Gas, Crude oil and Petroleum products, LPG, Electrical and Telecom signals and other underground networks. Following techniques are adopted in trenchless engineering viz:- For Repairs & Renovation Cleaning, Localized Repair Techniques, Lining Techniques For Replacement Pipe Bursting, Pipe Splitting, Pipe Eating, Lead Extraction & Replacement Systems In New Installations Impact Moling, Pipe Ramming, Auger Boring & Thrust Boring, Pipe Jacking, Micro Tunneling, Guided Rod Pushing, Guided Boring & Directional Drilling (Horizontal Directional Drilling), Rock Boring, Cable Pulling, Cable Blow In Systems In this report we shall be speaking of Guided Boring & Directional Drilling, which is also known as the Horizontal Directional Drilling which is ideal for the underground installation of Natural gas, electric, water, telecommunication or soil remediation lines - without excavation or trenching. What is HDD? HDD (Horizontal Directional Drilling) is a trenchless methodology that provides an installation alternative for underground utilities like pipelines / cables that can offer a number of benefits over traditional open-cut laying. Why use HDD technique? HDD is used in place of other techniques for the following reasons: Little disruption to surface activities Requires less working space Can be performed more quickly than open-cut methods.


lower cost deeper installation possible longer installation possible no access pit required shorter completion times fairly accurate directional capabilities safer for the environment

Areas where HDD can be used? HDD technique can be used to install new pipelines or replace existing ones For installation of municipal underground infrastructure systems Standards for HDD techniques? Currently there are no national standards regarding HDD installations for any pipe material, however in India, an apex autonomous body IndSTT (Indian Society of Trenchless Technologies) has taken up various initiatives to develop and popularize the application of Trenchless Technology in the nation. Certain guidelines and codes of practices for HDD have also been developed by IndSTT. Major elements for an HDD installation? A rig, which provides the physical means thrust and torque, to open the hole and pull in the product pipe. A transmitter/receiver system for tracking the location of the bore The down hole equipment - drill pipe, drill bits, and reamers, which converts the physical properties of the rig to open the hole and pull in the product. The drilling fluid, which serves to stabilize the hole, cools the down-hole equipment, and removes the spoils from the hole. The drilling fluid delivery and recovery system made up of tanks, mixing systems, pumps; and, when recycling fluids, a system of screens, filters, shakers, cones, etc. To remove spoils brought to the surface from the fluid. Procedures involved in HDD?

PLANNING It comprises of: Thoughtful Planning, Ascertaining Ground Conditions, Locating surrounding utilities, Bore profile design, Survey and plotting on paper, Considering Safety and Environmental issues and Selection of HDD machine of suitable capacity based on above factors.

DRILLING A PILOT HOLE Drilling is carried out by using a directional drill machine of required capacity, which pushes a bore head connected to hollow pipe into the ground at an angle. As each joint of drill rod is pushed into the ground a new one is added behind and the joints torqued tight using a hydraulic vice.


REAMING Upon reaching the exit point, the bit or bore head is detached and the end of the drill pipe is attached to a reamer or hole opener (for rock) if the borehole must be enlarged. The reamer is pulled back while rotating the drill rods with as many consecutive passes as required. Drill rods are added from behind the reamer or hole opener so that there are always drill rods in the borehole.

The pilot hole is enlarged (usually approximately 1.5 times the largest outside diameter of the new pipe) by pulling back increasingly larger reamers, or reaming heads, from the pipe insertion point to the rig side. To achieve the appropriate bore path size it may be necessary to perform several reaming operations. Generally, all reaming procedures prior to the actual product installation are referred to as pre-reams, and the final ream to which the product pipe is attached is referred to as the back ream.


PULL-BACK When the borehole is 25 - 50% larger than the pipe to be installed, the end of the pipe is connected to a packer/reamer or barrel reamer and then a swivel attached to the pipe to be installed and pullback commences. For some telecommunications or power cable projects, the drill pipe itself becomes the conduit and is left in the ground upon reaching the exit point. This type of installation is known as "drill and leave".

After the pre-reams, the pulling head and connecting product pipe are attached to the reamer using a swivel, a device that isolates the product pipe from the rotation of the HDD drill pipe. The product pipe is then pulled behind the final reamer back through the horizontal directional drill path towards the rig side. The Mahi River HDD Project

Background

GAIL Vadodara awarded the work of Rehabilitating / Repairing of their existing 12 Dabka Dhuvaran CS Gas pipeline to MECON Delhi as their Project Management Consultant for restoring the supply of natural gas to GSEC, Dhuvaran. A section of the 12 CS pipeline passing under Mahi River between Dabka Gajna section was swept away during the floods. This was due to the bank erosion of Mahi River on Dabka Village side wherein the bank got washed away by over 300 meters, exposing and breaking the existing 12 gas pipeline laid on the Dabka side of Mahi River.


THE BROKEN & EXPOSED PIPE IN MAHI SAGAR

Rehabilitation Options Available Since the damage of the pipeline was anticipated to be not within the earlier executed 1220 m HDD part of the pipe length, the Rehabilitation / Repair of existing pipeline by Open Cut Method was considered in the first instance. This method involved survey and detail investigation to identify the location and extent of damage, construction of temporary Coffer Dam/ Dykes etc. including installing well point system for creating working conditions suitable to carryout the pipeline removal / re-laying works inside river bed from Dabka side bank and replacing the existing broken pipeline with a new pipe string of approximately 750 m length which was to be laid at a 3.0 m minimum depth from scouring depth which effectively worked out to be16 m from deepest point of river bed. The proposal of rehabilitation by Open Cut Method was not opted for economic reasons. Besides shifting course of Mahi River was another deterrent and which further added to the issue of methodology to be adopted. MECON subsequently proposed restoring the pipeline by an all together new HDD by crossing pipeline under Mahi River at the same location. Considering the eroding nature of the river bank on Dabka side, an unusually long HDD of at least 2000 m length was proposed to cross the 1200 m wide Mahi river so as to punch out sufficiently away, about 500m from the unstable river bank on Dabka Side.

Uncertainties and Challenges The proposition of crossing Mahi river with a 2000m long HDD at nearly the same location was extremely challenging due to following reasons:

no one could anticipate the types of problems that one would encounter while undertaking such a big length crossing

there were very few agencies who in past had undertaken such long HDD crossings there had been repeated failures in the past while undertaking HDD works at this

location in Mahi river due to the typical soil characteristics.


the As-built details, data and records of the HDD section earlier carried out by GAIL in 1997 were not elaborate with regard to design, piping calculations and the nature of ground strata.

The sub-soil conditions for the proposed 2.0 km long HDD length at proposed location was unknown and unpredictable.

Execution Plan A drilling agencyM/s N R Patel & Co. had been appointed who had prior experience in HDD works and had a drilling machine of 250 Tonne capacity. Detailed site investigation works involving river and embankment survey work and geotechnical investigation were carried out inside the river by the drilling agency on either sides of the river bank on the proposed route to decide on the HDD drilling path parameters and profile. Apart from mapping of the Riverbed along the proposed alignment, 13 numbers of boreholes were drilled in and around the riverbed along the proposed alignment to study the geotechnical features and the sub soil profile. Based on the sub-soil condition, the maximum scour depth due to the highest flood levels were worked out. Keeping into consideration the material specifications of the pipe, the depth of the HDD hole with respect to the deepest point of riverbed, the drill hole path and profile were worked out. The pilot hole drilling work was the most difficult part of the project to complete. Right from the beginning itself, there had been repeated hold ups in drilling the pilot hole along the proposed path.

250 T HERRENKNECHT RIG IN OPERATION While drilling frequent trip outs and trip ins of the drill rods had to be undertaken at numerous instances due to various problems encountered while drilling viz: probe problem, sensor cable problem, non return of bentonite in down hole, problem in drill bit, pilot not moving in desired direction, high pushing torque and change in path of the HDD profile by making a fresh path. Casing pipes of various sizes and lengths were provided at the entry point side to ensure that the drilled hole remained intact, and to avoid undue thrust on drill rods / pipes due to high


pushing torque particularly at the bends, etc. Substantial time was lost in placing / replacement of casing. The casing pipes were replaced by changing casing size and length to avoid rotation of casing pipe inside the drilled hole and to arrest wobbling of drill rods.

The Failures The first pilot hole, which started from the Gajna villages end, could not be drilled beyond 1739m from the entry point. The hole could not be advanced further from where the upward lift of the pilot was to be started. Even after trying to drill along a deviated path, the forward drilling length could be achieved beyond 1624 m from the Gajna end in the deviated hole. The thrust of drill rig appeared to get dissipated in the surrounding ground beyond this length. This was due to an unfavorable soil condition / unduly enlarged bore hole down below due to which drilling rods were getting bent much inside the down hole and further drilling could not proceed further. So, it was decided to drill a separate hole along the approved drill alignment from the other side of the river bank i.e. Dabka village side by using a separate drilling rig and intersect the new hole with the existing deviated hole of 1624 m length. Considering that there may be boulders and adverse soil conditions, additional exploratory bore holes were got conducted at certain locations, between the already drilled bore holes, to get a more realistic and clear picture of the sub soil condition. Additional boreholes were drilled beyond 1750 m point. At this point a second drilling machine from Dabka end had also been deployed. Even after drilling 390m from the Dabka end, the point of intersection with the hole from the Gajna end could not be accomplished as the ends of the holes couldnt be properly guided into each other. One of the reasons for not achieving this was non-deployment of specialized tracking tool, Paratrack-2, required for making the precise meet of the two ends by the drilling agency. Moreover in the event of making repeated attempts to intersect the two bore holes using the Tensor tracking tool, the drill rods gave way and the bore hole tools viz. the drill bit, the Tensor tracking tool and the non magnetic color and a few drill rods were lost inside the downhole drilled from Dabka side. As a result the pilot hole drilled so far became redundant and had to be abandoned all together.

Observations, Investigation & Suggestive Measures adopted

The loss of 1739m+390m drilled length of pilot hole, from Gajna side and Dabka side respectively over a period of over three months, along with loss of drill tools and drill pipes called for an in depth analysis, introspection and detailed deliberations for ascertaining the reasons of this failure. From the results of additional exploratory bore holes drilled, it was found and noted that the depth at which the pilot hole was being laid on Dabka side (approx 1750 m away from the entry point side) was having a layer of Sandy gravel and this layer was not over the entire depth of the borehole. The layer above it was silty sand. Since the river portion was already crossed without any hindrances with the pipeline laid at ~16m below the deepest bed level, the executing agency was asked to change the drill path profile beyond the 1600 m point and start lifting up the pilot hole avoiding the Sandy gravel layers. The data of the pilot hole drilled upto 390m from Dabka side wherein problems were faced while drilling pilot hole in the first attempt, was also used to collate the exact ground details. Further, additional exploratory (survey) boreholes were got drilled and data collected on Dabka side. The boreholes data and the pilot hole drilling data confirmed presence of gravel at different locations. Based on this, the HDD profile was re-designed and customized to avoid the gravelly layers on the exit side in the second attempt while drilling from Gajna side.


While making pilot hole from the Gajna end in the second attempt, a 300m long casing was provided on the entry side right from the very start. This was so done to make the requisite push force available at the pilot drill point even as the length of the drill string gradually increased to over 2000m. This was also provided to avoid loss of torque from the rig on the curved portion of the pilot hole where sticky clayey layers were present.

Success at Last A new pilot hole of 2008m was drilled at a different location, about 2.0m away from the earlier drilled hole, from Gajna side. Based on MECONs advise the Paratrack pilot tracking system was used along with a single rig of 250 T capacity instead of the Tensor tool used earlier to successfully punch out the hole on the other end at Dabka side in the second attempt. Other activities which followed included cleaning the pilot hole using wiper sub, removal of 300 m long casing pipe and widening the hole by reaming with 18 fly-cutter reamer, clean pass using 18 barrel reamer and pull through of the pre-fabricated, pre tested pipe string.

2017M LONG SINGLE PIECE PIPE STRING BEING PULLED THROUGH The remarkable feat of completing the pulling of 12 NB pre-fabricated & pre-tested pipe string of 2017m length inside a 2008 m drilled HDD hole was finally achieved using a 250 T capacity rig of Harrenknecht make. The pulling of the pipe which started at 07.30 hours from approximately 500m from the unstable bank of Dabka side was finally completed at 19.00 hours in a single go without any hiccups / hurdles when the pipe surfaced approxim

Documents

KM Bulletin Tech Papers on CNG and CGD and HDD Article