draft report on natural gas transmission pipelines and cgd networks by committee on natural gas...

8/6/2019 Draft Report on Natural Gas Transmission Pipelines and Cgd Networks by Committee on Natural Gas Pricing

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Draft Report

On

Natural Gas Transmission Pipelines

And

City Gas Distribution Networks

- Prepared by Committee on Natural Gas PricingOil Industry Safety Directorate (OISD)


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City Gas Distribution Networks

S.No. Description Page No.

1.0 Introduction 44

2.0 Scope 44

3.0 Definitions 44

4.0 Statutory Regulations 45

5.0 Layout & Facilities 45

6.0 Laying of Pipeline 48

7.0 Testing & Commissioning 50

8.0 Operation & Maintenance 51

9.0 Emergency Plan and Procedure 52

10.0 Training 53

11.0 Records 54

12.0 References 54

Annexures

I Typical Piped Natural Gas (PNG) Distribution System 55


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1.0 INTRODUCTION

The use of piped natural gas (PNG) fordomestic, commercial and industrial purposein cities is gaining increased importance as analternative fuel. PNG is being usedinternationally with proven success.

PNG is a mixrure of hydrocarbon gases andvapours consisting of principally Methane ingaseous form. The PNG network consists of receiving natural gas from suppliers at CityGate Stations (CGS), Steel Mains. PressureRegulating installations (PRl), Poly Ethylene(PE) Mains and Supply System to end users.A lypical system of piped natural gasdistribution is given at Annexure-I.

Safety in PNG distribution is important Invie\'" 'of the highly inflammable nature of thega s and densely populated areas in which rhenet\' ...ork is installed.

This slandard aims to ensure safe design.construction, operation & maintenance of PNG distribution to various customers vlz.Domestic, Commercial and Industrial so as toprovide a level of safety and protection of lifeand property.

This standard has been prepared forsupply of Piped Natural Gas to domestic,commercial and industnal users

d. CNG Dispensing facilitIes are covered on0ISO-STD179

3.0 DEFINITIONS

a Authorised Person: A person trainedand assigned to carry out a specific job bythe owner or PNG Distribution Company.

b Active Regulator: Regulator in PRI that

normally controls the outlet pressure

c. City Gate Station (CGS): An installationwhere PNG operator receives the naturalgas from the supplier The first stagepressure regulation and odorization ofnatural gas takes place in CGS. A typicalschematic layout of facilities/ equipmentInstalled al CGS is given at Annexure-II

d. Competent Person: A person recognized b; .the concerned Statutory Authority for thepurpose in respect of which the competency isrequired.

e. Consumer Meter (CM): A meter thatmeasures gas delivered to a customer forconsumption on the customer's premises.

f, Creep Relief Valve: A relief valve having

maximum 1 % flow capacIty and ISInstalled to prevent over pressurization ofthe downstream system.


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I. Maximum Incidental Pressure (MIP):Max. Pressure, which a system ,sdesigned to experience under faultcondition and is 'ess than or equal to 1.1times the operating pressure.

m. Monitorl Active (Regulator) Anarrangement of two regulating devices inseries whose pressure settings arestepped so as to allow one (Active)normally to control the outlet pressure andIhe other (Monitor) to assume control inthe event of failure of the active device tothe open position

n. PNG Distribution System: A natural gasdistribution system & facilities in which thepiped natural gas (PNG) IS distributed toresidential, commercial & industrial

customers.

5.1 1 The faCilities at the pressure regulatingstation shaff be located in a manner tofacilitate operation and ease ofmaintenance & inspection. The typicalschemalic layout of facilitiesl equipmentinstalled at CGS and PRI are given atAnnexure II & III respectively. Additionally,the facilities at CGS and PRI shallconform to the following:

a. For CGS. the minimum separation distancebetween the nearest equipment and theboundary wall shall be 6 meters.

b The above ground PRI shall be lnside anenclosure with sufficient ventilation. Theseparation distance between enclosure and theboundary wall of nearest building! structureshall not be less chan 2 meters.

d. The environmental effect and associated

hazards of rife and explosion due to therelease of large volumes of gas toatmosphere shall be considered in case arelief valve is installed as a pressurecontrol device. Creep relief valve can beused to prevent over pressurization of thedownstream system.

o. Pressure Regulating Installation (PRI):PRI is an Inslallation in the PNG networkwhere second stage pressure regulationof natural gas takes place aher CGS Atypical schematic layout of facilities!equipment installed at PRI IS given at

Annexure-IlL

p. Shall: Indicates mandatory requirement

q. Should. Indicates recommendation or thatwhich is advised but not mandatory

Service line: A pipe connectinga gasmain up to and including a meter controlvarve~ A service line may supply morethan one meter in a particular building orIn two adjacent buildings.

s. Service Regulator: Regulator Installed on

c.

e.

f

There shall be minimum tWO safety devicesand at least one shall be a slam-shut "'Jlveoperating on over-pressure for installations

operating above 4.0 barg.

In case, a monitor regulator is used. it shall bethe first acting device in the pressure safet~

system.

PNG shall be supplied after adequate filtrationto prevent erl?sion and damage to cqlllpmenU

h l h ll b i


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S.U ISOLATION OF CGS

Quick acting isolation" valves shall be providedat CGS for emergency isolation purpose.

5.2 PIPING AND VALVES

5.2.1 STEEL PIPING

a All ngld piping. tubing, fittings and other.piping components shaH conform to therequirements clause 5.2 of part 1 of this standard. Pipe having Dlt ration greater than 96 shall not be used.

b. The steel piping shall be designed formaximum operating pressure of 19.0barg. at temperature ranging between (-)29 Deg. C to (+) 65 Deg. C

c. For underground steel piping network,

suitable corrosion protection like cathodicprotection, wrappingl coating etc shall beapplied Provisions of clause 9,0 of Part 1 of this standard shall be applicable,

d. The above ground mains shall be paintedyellow for identification.

e. The cast iron pipes shall not be used inthe PNG network

5.2.2 POLY ETHYLENE (PEl PIPING

SUCh valves shall be installed to facilitatemaintenance of system and to allow forspeedy isolation in the event of damageThe location of the strategic valves shallbe decided based on the risk associatedWith maintaining the gas supply and tofacilitate maintenance, repaIr,modification, testing and commissioningetc. In no case, dIstance between tvvostrategic valves shall exceed:-

a. 3 KM for steel pipelines.

b 1KM for PE Pipelines of diametermore than 63 mm

For PE Pipelines less than 63 mmdiameter, the distance between strategic

" valves shaH be based upon risk analysis.

Such valves shall also be provided oneach riser, upstream of each meter and atboth ends of river & railway crossing ..

53 CONSUMER INSTALLATIONS

5.3.1 Gas received through PE Pipelineundergoes further pressure regulation atdomestic! commercial! Industrialconsumer end. These installations include

isolation valve, pressure regulator capableof shutting off the down stream gas supplyin case of low & high pressure, meter etc.


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5.4 ROUTE OF PNG PIPELINE

54.1 The PNG pipeline route should avoid;

b) Conlact telephone number(s) inemergency.

cj Locationcode

5,] PNGOOOURISATlON

a, Areas congested with other undergroundutilities like power, water, telephone etc.

b. Close proximity to unstable structures orwhere construction could lead to damageto pipeline.

c, Close proximity to highly populatedbuildings such as schools, public placesetc.

d. Ground areas of running sand, gravel orflood risk, water bodies.

5.6

d) Warning-"Hlgh Pressure Gas Line"and "Other Ulliities to take permissionfrom PNG distribution companybeforedigging"etc.

PROXIMITYTO PROPERTIES

The minimum distance between steel

pipelines, having operating pressure of 4barg or mOreand the normally occupiedbuildingsshall be 2 meters.

e Heavily traffic-loaded routes where theroad has not been constructed to suitablestandards.

f Areas of known or suspected aggressivesoil conditions,

g Landfill sites.

h Steel pipingshouldavoid;

i. Close proximityto existing CP systems,particularlyground-bed loeations

ii. High stray direct current, typically nearDCtraction systems.

a. Natural gas supplied through PNGdistribution shall have a distinct odour,strong enough to detect ItS presence. In

case ethyl mercaptan is used as odorant,the concentrationrange shall be 7 to 12.5PPM.

b The odourisation and filtration systemshall be located in a separate workingarea, but within the same fencing. Thereshould be a clear safety distance of 1.5 Maround the odourisation and filtration

systemto facilitate easy maintenanceandpersonnel movement.

c. Risk Assessment of odourant inslallationsite shall be carried out. The storage of


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Each installation shall be equipped withthe following facilities for fire protection

5.8.1 CITY GATE STATION (CGS)

a The entire gas handling equipment!facilities Installed in CGS shall becovered WIth water sprinklers. 6.1

192 (Safety Practices During Construction) shall be complied. PE pipe shall not be installed above ground provided it is encased in metal pipe protected against atmospheric corrosion.

Following shall also be complied;

c. Electricity cables shall be treated as"Live", unless the owner certifies them as

"Dead".' The dead cable shall also bechecked for any residual voltage.

a. Road signs, warning lamps and barriersystems shall be provided on highway or

other work locations which are accessedby pedestrians or vehicles.

d. Where it is necessary to Cf'OSSor runclose to any other utility, a minimum of250 mm clearance shall be maintained. Incase the clearance is less, appropriateprotection measures shall be taken. Therelative position of PNG pipeline Withrespect to other underground utilIties shall

be as given below

b. The firewater storage shall be calculatedbased on following cooling rates for

minimum4

hours

Scrappers/Filters 10 Ipm! sq m of surface.Other areas 3 Ipm! sq. m of surface

c Adequate fire fighling access. means ofescape in case of fire and segregation offacilities should be provided so that theadjacent facilities are not endangeredduring a fire.

d Addilionally. following fire extinguishersshall be provided at the city gate stalion

I. Four numbers 10 kg OCP

iiTwo numbers 225 kg OCP

iii One number 10 kg Foam

iv. Two numbers 4.5 kg CO,

b. Underground utilities shalldisturbed or altered withoutconsent and approval of theauthority concerned

not bethe priorowner or


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At idenlined locations pipelines shall beprovided with, Impact protection fromexcavating machinery as indicated in thefig 1(a) & 1(b). 'h' shall not be less than500 MM.

The bed of the trench shall be free ofsharp objects, stones etc. The trenchshould be padded with soft sOil J sand tominimumof 100mm belowthepipe.

h. A layer of brick! concrete shall be laid orImpactresislant tape shall be laidover Ihe

on the pipeline covering its entire length.

o. ,

i"

Location Min. Coverin meter

Industrial, Commercial 1.0and Residential Areas

Stream, Canal and 1.5other minor watercrossingsDrainageditchesat 1 0roadwaysandrailroads

RockyAreas 1. 0RoadCrossings , 1. 2RailroadCrossings 1 7

Inside the building I 1 0society premises

Wherever Ihe minimumdepth of coverasabove is nol possible,a risk analysisshallbe carriedout to delermine Ihe addillonalprotection requirements.

Figure 1 (a) Concrete Slab

. --------- -------

6.4 JOtNT REQUIREMENTFOR PE PIPEa, Pipe or tubing shall not be threaded.b, Joint procedure (mechanical,

adhesive or heat fusion)qualification shall be done andproven by test.

c. Flanges or special joints s,hall beused provided they are properlyqualified

0 :6.5 During installation of PE plpmg, care

lH'lall be taken to prevent damage topiping and components Gouge cuts


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6.3 SERVICE LINE

The following shall be complied:

a A service line shall not be laid under thefoundations of any bUilding.

b. Service lines shall not be laid Inunventilated enclosures.

c. All Poly Ethylene (PE) pipe and firtlngs

shall be laid underground and shall not.beexposed. The service lines, wherecoming above ground, shall be only madeof GI/Carbon Steel piping. with adequateanti corrosive coating.

d. Wherever the riser IS to be laid throughconfined spaces like basements, onlywelded risers shall be used. Riser shall beinstalle d with a mintmum gap of 25 mm to

wall and supported at every 2 m.Ventilators shall be provided in confined space.

e. Inlerface Joint shall be prOVided overground. In case interface joint is providedunderground. it shall be protected againstcorrosion etc.

Design Pro Strength Du ratic nlOP) Test Pro Hydro.(H)/ (bar) (bar) Pneu. {PI

Up to 01 0.3 P30 min

From 0.1 to 20 P1.0 30 mln

From 10 to 3.02.0 H (4hrsl

From 2.0 to H7.0 . 4hrs

I From 7.0 to 150P H100.0 4 hrsDuration of test shall be after stabilization of pressure.Tightness test shall be carried atoperating pressure for a duration not lessthan 30 minutes.

7.2.2 HYDROSTATIC TESTING

a Steel Pipelines and mains shall be testedhydrostaltcally to a pressure not less than1.5 times the Maximum OperatingPressure. Suitable relief valve set at 5%over the test pressure, shall be fined toavoid over pressurization.

7 . 0

7.1

TESTING & COMMISSIONING

Following shall be compiled beforecommencing the testing & commissioningactivities:

b. The duration of hydrostatic test for steelpipeline shall not be less than 24 hrs or as

specified by respective code to which thepipeline IS designed and accepted by

statutory authority


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73

b. TEST DURATION

The duration of pneumatic testing ofservice line and internal insta!!ation shannot be less than W 30 minutes.

COMMISSIONING OF FACILITIES

All fire protection and detection facilitiesshall be in place before commissioning.

established as an integral part ofoperations.

e. Aclion In the event of emergency shall beclearly established and understood by allconcerned and displayed prominently.

Important operational activities shall belogged and records of such activities shallbe maintained

All facilities Ie. CGS, PRI, Pipelines etc.shall be purged and commissioned as perapproved procedure after due checks andcertification by' the authorised personnel

8,0 OPERATION & MAINTENANCE

8.1 Operating procedures, With sUitableoperational controls based on formalhazard identification & risk assessment,shall Include lollowing safety aspects-

a. Adherence to work permit system in line

With 0150-5TO-105

b. Management of change in line with 0150-GON-178,

g. Al l PNG operat ions shall be carried outunder the superVision of authorisedperson(s).

h Limits of operating parameters includinglevel, pressure and any other condition asset for sound and safe operations shallnot be exceeded. In case any abnormaloperating conditions are encountered, thecauses shall be investigated andcorrective achons taken

1. The operating staff shall maintain vigilancefor detection and control of any leakug.,;.

.I- ExplosimeteL duly callbrated. shaH beavailable at CGS to monitor the leakng.t atflanges and instrument tapings.

c. Selection 01 electrical equipment as perhazard area classIfication & maintenancein line With established 0 & M praclices!statutes,

k. A well-designed system of periodic inspeclionfor all facilities of PNG shaH be formulated tomaintain it in safe operable condition all the

time.

d Provision of PersonalEquipment (PPE), Protective l. Safety audit of the PNG distribution syskmshall be undertaken & certiticate of fitness.declaring integrity with respect to equipmcnl.


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n. All recommendations of the safety audit/ inspections shall be complied in a time boundmanner and records maintained thereof.

o. Disassembly or removal of the facil it ies andcomponents of equipment whilst any part of the system is under pressure is hazardous andshall not be undertaken unless the system isde-pressurised, gas freed and certified_

p. The system of permit to work shall beestablished for nonrout;ne works in line withOISD-STD-105 and such works shall beundertaken with full knowledge and approvalby authorised person.

q. Equipment appurtenances, protection devicesassociated with the PNG system asincorporated in the design shall be tested.maintained, repaired and replaced asrecommended by the manufacturer.'

r. Preventive maintenance schedules shall bedrawn for all equipment in accordance withmanufacturer's recommendations andestablished mandatory ! recommendatorystandards. Records of all preventivemaintenance undertaken shall be maintainedand updated from time-to-time.

s. Calibration of meters/ gauges etc. shall be

carried out, documented and records kept.

t. The Functional Test of Active/ Monitor

e. Close Coordination among utility companiesshall be carried out to avoid damages to theutilities.

84 MODIFICA nONS TO LIVE PIPELINES

All modifications '_ e . additions!altemations shall be carried out inaccordance with applicable code ofpractice! approved procedure. Provisionsof OISD-GDN-178 (Guidelines onManagement of Change) shall becomplied.

841 PRESSURE CONNECTIONS

a. Metallic Piper,nes

Connection should be made to livemetallic pipeline by direct drilling andtapping using proprietary fittings and "nogas to atmosphere" drilling equipment (hottapping). Hot tapping procedures for steelpipelines At annexure V.

b. PE Mains:

Only fused connections shall be made toPE mains using compatible polymericmaterial and as per applicable code

Subsequent to any alteration/ modification, the complete system shallmeet the existing testing & commissIoningrequirements of the system as per clause


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III. Accidents or other emergencies, which canaffectlhe PNG supplies.

IV. Civil emergencies

v Any other risk arising from the existence oroperation of the PNG system.

The above emergency plan shall bedisseminated amongst all personnelinvolved and ensured that theyunderstand their roles and responsibilitJesin the event of an emergency.

c. The in-charge of the PNG distnbutlOn

shall maintain close liaison with FIreService, Pollee, District Authorities andthe Gas Supplying Organization

d. Provision of round the clock emergencycontrol room equipped with effectivecommunication system shall be made.Emergency Contact telephone numbers ofemergency response team members,emergency servIces, mutual aid

industries, district authorities, enforcingagencies, contractorsJ vendors, fifebrigade, civic agencies etc shall beavailable.

e The control room shall be equipped withEmergency vehicle having communicationsystem, first aid fire extinguishers, leakdetection and repair tools & tackles etc.All necessary maps and plans & P&IO's,Material Safety Data Sheet (MSDS), etc.shall be available.

Operating Company shall participate in

company prior to taking up anyexcavatIon I digging activity within thecity limits by other ulilities.

iv. Prompt reporting of gas leak! damagesshall be done.

v. Use of designated ulil ity corndorprovided by local administration shall bemade,

10.0 TRAINING

10.1 The objective of training is 10 prOVide good

understanding of all the facets of PNGdistnbution activities including operations,procedures, maintenance and hazardsand the risks associated with its handling.Training shall ensure thai the jobs areperformed In accordance with the laiddown procedures and practices.

Training shall be imparted to the staffattached with the PNG distribution at thetime of Induction, which is to be followedup by periodic refresher courses. Thetraining programme shall inter alia cover following aspects:

a Hazardous characteristics of PNG

b. Familiarization \\lith operational pH)cedures &practices.

c. Commissioning of new facilities andequipment..

d Hands on experience on operation of


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10.2

103

Proper records for the training andrefresher courses shall be maintained.

Training for employees & contractors ofother utility companies should be done tomake them aware about hazardsassociated with leak! damages andrequired actions

s HAZOP/ Risk assessment studles/ compliance to recommendations

All operation & maintenance manuals

u Interlock testing documenUby passrecords etc.

12,0 REFERENCE S

11.0 RECORDS

The PNG distribution company shallmaintain following recordsl documents:

a. Design/ specification documents

b. Pipeline alignment sheets for MP steelpipeline

c. Pipe Book! Installation Records

d. Vendor and subcontractor assessmentsand records

e. Surveillance inspection and maintenancereports

f. Material certification including dimension,metallurgy, DT and NDT, strength,

tightness, performance and functional" ' report

a, ASME-B31,8 - Gas Transmission andDistribution Piping Systems

b, IGEITD/1 - Steel Pipelines for Highpressure Gas Transmission

c IGE/TD/3 - Steel and Pipelines for GasDistribution

d. IGE/TD/4 - Gas Services

e IGE/TD/13 Pressure RegulatingInstallations for transmission andDlstnbution Systems

f IGE/SR/16 - Storage of Odorant and Useof Odorant Systems

g 0ISD-STD-10S - Work Permit System

h 0ISD-STD-113 - Classification of Areasfor Electrical Installations at HydrocarbonProcessing and Handling Facilities


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SteelMains j- INLET PRI Combined Meter Appliances (Domestic,FROM Comm.& Industrial

SUPPLIER PEl Steel PEl SteellMains Copper

Service

/ SleelCity Gate Mains PRllndustrial Meter Industrial AppliancesI~>-StationICGS) PEl Steel PEl SleelMains service

Steel

Mains PRIResidentiall Meter Dom.! Comm.Commercial

AppliancesPEl Steel PEl Steel! .Mains Copper

Service

Typical Piped Natural Gas (PNG) Distribution System

5 5

Annexure-l


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TYPICAL LAYOUT OF A PRESSURE REGULATING INSTALLATION (PRI)

Outlet

f f CreeoNR V[

Isolation

Annexure-III

57

Stand-by Stream

Standard on Natural Gas Transmission Pipelines and City eas distribution networks

Active! MonitorRegulators

Slam ShutValve

INLET


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Standard on Natural Gas Transmission Pipelines and City l!as distribution networks

ANNEXURE - IV

1. Recommended specification of GI pipes used for domestic gas piping above ground up to the isolation valve after the meter

Pipes shall be conforming to IS: 1239 (Part-1) - 1990. The manufacturer shall have a valid license to use ISI Monogram for manufacturing ofpipes in accordance with the requirements of IS: 1239 (part-I) - 1990.

NOMINAL 15mm 25 mm 50 mm 80mmBORE

GRADE HEAVY HEAVY HEAVY HEAVY('C' CLASS) ('C' CLASS) ('C' CLASS) ('C' CLASS)

O.D.mmmax. 21.8 34.2 60.8 895Min 21.0 33.3 59.7 880

THICKNESS mm32 4.0 4.5 4.8

NOMINALWEIGHT 1.44 293 6.19 9.90Kg/mtr

Note:

Maximum tolerance on thickness (-)10%, Tolerance on weight for single tube 10% and for quantities per load of 10 tonnes, 7.5%.

Pipes shall be designed to withstand a test pressure of 5 MPa (50 Kgf I em'), maintained for at least 3 second without showing any kindof defects

Eddy Current test may be done in place of hydrostatic test as per the procedure given in Annex - C of IS 1239 (Part-1) - 1990. All Galvanised Tubes shall be Zinc coated by hot dip galvanising in accordance with IS: 4736-1986 & its relevant parts. Minimum mass of zinc coating determined as per IS: 6745-1972 shall be 400 gms I m' The zinc coating on external and internal surfaces shall be adherent, smooth and free from such imperfections as flux, ash & dross

inclusions, bare patches, black spots, pimples, lumpiness, runs, rust stains, bulky white deposits and blisters. Rejection and acceptance for these defects shall be as per Appendix-A of IS: 2629-1985 The galvanised coating when determined on a 100 mm long test piece in accordance with IS: 2633 - 1986 shall withstand 4, one -

minute dips.

58


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The adherence of zinc coating on tubes above 50 mm nominal bore, shall be determined by the pivoted hammer test given in IS . 2629 -1985

Each pipe shall be legibly and durably marked at intervals of not more than one metre with the following information (i) Manufacturer's nameor trade mark, (ii) Class of Pipe - HEAVY, (iii) Indian Standard mark -ISI, (iv) Batch No. of Production, if any.

2, Recommended specification of copper pipes used for domestic gas piping inside the residence up to the isolation valve after themeter

For a copper service in domestic natural gas installations, materials supplied shall be in accordance with BS EN 1057:1996, it has replacedthe copper tube standard BS 2871 Part 1. BS EN 1057 ensures the quality of the copper product by specifyin9 the pipe in terms of itschemical composition, mechanical properties (tensile strength, hardness, elongation etc.), dimension and tolerance, surface quality, freedomfrom defects and suitability for pipe bending.

Copper pipe work shall be jointed by soldering or brazing, using mechanical compression or capillary type fittings. Fittings for use in joiningcopper tube shall be as per BS EN 1254 Parts 1 and 2. Fittings for capillary soldering and brazing are specified in Part 1 and compression

fittings are specified in Part 2

Soft soldering utilises filler metals with melting points at temperatures up to 450'C. Filler metals shall be as per BS EN 294531994 - Softsolder alloys - Chemical compositions and forms. Solders for use with copper tube and fittings generally melt within the temperature range180'C to 250'C. Compression fittings shall be comply with BS 864 Part 2 or BS 2051 Part 1.

For capillary fittings:

Soft solder shall not be used for pressure in excess of 75 mbar If the operating pressure is to exceed 75 mbar then a solder with a melting point of not less than 600 degrees C shall be provided the

pipe diameter does not exceed 35 mm. This equally applies to brass fittings.

Height limit for copper risers: Although there is no specific guidance regarding maximum height of copper risers, IGE/UP/2 only allows theuse of steel for risers above heights of 15 meter. Thus, unless local information is available to the contrary, 15-meter maximum height shallbe considered safe due to weight and mechanical strength of material.General guidance in BS 6891 also states that copper pipe work is not acceptable inside a protected shaft. Requirements for ventilation andfire stopping shall apply to ducts conveying copper pipe work For an external copper riser system, protection against lightning conductorsshall be considered.

Last but not least, a copper gas line shall never be used as a ground for an electrical system.

59


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Standard on Natural Gas Transmission Pipelines and City eas distribution networks

3. Recommended specification of rubber hose used for connecting the Gas Stove after the isolation valve to the Gas Stove.

Rubber hose shall be conforming to IS: 9573. The hose shall consist of lining, reinforcement and cover.

The Hose should not be exposed to internal or external temperature exceeding the recommended limits, as high heat conditions can causean adverse effect on the hose by degrading the Elastomer and thereby reducing fitting retention.

The hose size must be capable of handling the required flow volume. Using the smaller than required diameter of hose for a given volume offlow would, result in excessive fluid turbulence, pressure drop, heat generation and tube damage.

The hose should not be bend or flex beyond the specified parameter (refer, Table 1 Dimensions and Bend radii for Rubber Hoses, IS 9573),as this would put excessive stress on the reinforcement and severely reduce the ability of the hose to withstand pressure.

Hoses in service should be checked every year, for leakage, kinking, corrosion, abrasion or any other signs of wear and damage. Any hoseworn or damaged must be removed from service and replaced immediately

4. Recommended specification of the domestic gas burner.

The gas stove shall be manufactured and checked in accordance to IS: 4246, IS: 11480 and IS 5116. The following tests are conducted, (i)strength testing, (ii) thermal efftciency, (iil) combustion, (iv) gas soundness test, (v) floor wall & ceiling temperature measurement (vi) gasconsumption test.

The jet nozzle of the gas burner shall be designed for a standard length of 11mm, with a tolerance of 0.2mm. The bore at the bollom of thehose is of 2.38 mm diameter (tolerance +0 1, -0 15). The hole on the top of jet is of diameter 125 mm or 1.10 mm (tolerance +0.02, -0.01)based on the capacity. (Refer fig. 1 & 2)

6 0


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I1'i

;j

/ " i l i...:.'.

II

r -_ ..1 \ 1

.'f~i'

Jet Nozzle - 125

61

Jet Nozzle -1.10


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Annexure - V

Details of the online procedures for Steel pip.elines where hydro testing is not recommended. " Hot tapping"

Procedure for Hot tapping on pipelines in-service shall comply to IS: 15679: 2006. Hot tapping is the technique of attaching a mechanical orwelded branch fitting to piping or equipment in service. and creating an opening in that pipeline by drilling or cutting a portion of the pipingwithin the attached fitting.

Hot tapping shall be performed when it is not feasible, or impractical to take the piping out of service, or to purge or clean it by conventionalmethods. A hot tap connection can often be safely made without interfering with the process operation.

Prior to conducting hot tapping, a written plan shall be prepared which includes the following, Connection design Hot tap procedure Detailed written welding procedure Health, safety, fire protection, emergency response, and other appropriate procedures & instructions.

Additional information when developing a written plan may be obtained from Section IX of the ASME Boiler and Pressure Vessel Code forqualification of welders and the fundamental ASME Code welding procedure to be employed.

Note: Section IX does not cover the condition encountered while welding on in service piping containing flammable and combustible liquids.Refer to API Recommended Practice 1107 for qualification of welders and the welding procedures to be employed when welding on in-service flammable and combustible liquid piping.

The tightness of bolts, packing, packing nuts and any by-pass line shall be checked to avoid any possible leakage. The test pressure shouldbe atleast equal to the operating pressure of the line or vessel to be tapped. But it shall not exceed the present internal pressure by more

than approximately 10%, in order to avoid possible internal collapse of the pipe or vessel wall.

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draft report on natural gas transmission pipelines and cgd networks by committee on natural gas...

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