Sizing Remi Plant

8/8/2019 Sizing Remi Plant

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SIZING OF

REMI PLANTS


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PROCEDURE "SIZING OF REMI PLANTS"

1) FOREWORD (SCOPE - OBJECTIVES - LIMITS)The sizing engineering, functional and resistance standards of a natural gas receiving,

reduction and measurement plant, set by the Transporter as minimum requirements, aredescribed in this procedure.

This procedure has been drawn up in accordance with the principles set forth in currentnational and international technical standards and law and on the basis of the specificexperience of the Transporter in the field in question: current law provisions must beobserved in all cases as regards the safety, engineering, construction and maintenance ofmeasurement instruments.

The main sizing criteria for natural gas receiving, reduction and measurement plantsillustrated in this procedure:

provide the minimum technical-construction sizing criteria for REMI plantswithout ruling out the adoption, by the owner, of upgrading solutions agreed onby the parties;

define pressure, temperature and flow rate parameters needed for engineeringpurposes;

classify REMI plants according to public or non public utility and interruptibilityand, on the basis of this classification, define the sizing criteria of the regulationand measurement units; said destinations are selected under the full and soleresponsibility of the owner of the plant;

indicate the charatersitics of materials and instruments; indicate the formulae and parameters required to calculate plant sizing; indicate the utilisation fields of the primary measurement system (volume and

venturimeter measurement) and the standardised engineering configurations inaccordance with national and international standards;

prescribe the use of suitable equipment for automatic collection and processing ofmeasurement data and relative remote transmission.

1.1)Plant with adjusted pressure and temperatureThe building blocks of REMI plants are the following, described in the order in whichthe gas flows:

a) Upstream section, including the pipeline section between the delivery point and theupstream filter manifold, the on-off valves, the insulating joint and emergency valve(optional)

b) Filtering unit (to split liquids and/or solid particles that may be in the gas)c) Preheating unit (optional)d) pressure regulation plant, including service regulators, control and emergency

regulators ("monitor"), shutdown device (optional), blowdown valvee) metering plant and associated by-passf) exit section, including downstream emergency valve, the on-off valves and the

insulating joint.


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In addition, the following elements are also components of the REMI plant :

g) fuel system for the preheating unit (optional)h) odorization plant (optional)

(The odorization of the gas for domestic and related use in the distribution networks

is requested by the law N.1083 of 6-12-1971.The odorization plants are regulated by the rule UNI-CIG 9463 and must be installeddownstream of the gas measurement.The schemes contained in this procedure do not cover the odorization plant).

To assure continuity of operations the units b) c) d) are usually installed in series in twoparallel lines. These lines are usually called regulation lines.Solutions different from those presented in this procedure may be adopted if equivalentor if they provide improvements from the functional point of view: the technicalassessment will be carried out on a case by case basis.

1.2)Plant with pipeline pressure and temperatureMeasurement plant with variable pressure and temperature, in the case of particularoperational conditions, can be installed, after agreement between the parties, upstream ofthe pressure regulation. In any event, the measurement plant will be installedimmediately downstream of the filtering unit. The scope in this case only covers themeasurement plant or the installation of all the plant parts described in points 1.1c 1.1d 1.1g 1.1h.

1.3)REMI plant with max upstream p 5 barThese types of plant, consistent the other sizing criteria described below, must bedeveloped in accordance with the criteria contained in Attachment 7.

The main difference with plants where max upstream p > 5 bar is that plants 5 areallowed a filtering unit with lower performance, but this must still assure the normalfunctioning of the downstream plant.If these plants are "Gas pressure reduction plants according to the rule UNI-CIG 8827,their development should be consistent with this rule. Attachment 7 contains its mainfeatures. In the Attachment 7 there are also some schemes valid for REMI plant with maxupstream P 5 bar, not reduction plant, with Qimp. < 300 m3/h and with fiscalmeasurement of the volumes only.

1.4)Functional types of the plantsPlants have different characteristics according to the following types of customer

supplied:a) Non-Interruptible and Public Utility (Households, Hospitals, Schools, Nursing Homes,

etc. for which unplanned supply interruptions will have serious impacts and may giverise to safety issues).

b)Non-interruptible and not Public Utility (Industrial customers, etc. for which unplannedsupply cut in the gas supply may have significant impact).

c) Interruptible at any time (customers for which unplanned supply interruptions haveminimal impact).These categories are assigned by the owner of the metering plant and documented assuch.


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1.5)Accessory REMI plantsIt may be necessary, for fiscal reasons and in order to ensure correct measurement, tohave an accessory measurement plant parallel to the main one. In this case the minimumconfiguration (concerning an interruptible plant with supplied flow rate < 300 m3/h) iscontained in the scheme FA of Attachment 7. If the plant is not interruptible or with a

supplied flow rate > 300 m3/h, the same approach should be used, consistent with thisprocedure and attachments, and considering the possible installation of other equipment(e.g. filters or regulators). The accessory REMI plants will normally be locateddownstream of the main measurement plant.

1.6)Law and standard referencesThe structure of the regulation and measurement plant described in this procedure, as faras the safety and the functional aspects are considered, complies with the rule UNI-CIG-9167 and with the rules EN 12186 (pressure regulation plant-functional requirements) EN1776 (measurement plant-functional requirements).The solutions to be implemented for cases not covered by this procedure, or not specified

in detail, should be agreed in advance with Snam Rete Gas. In designing the plant, inaddition to the criteria contained in this procedure, the following rules should be takeninto consideration:

EC laws and Directives in force at the time of the design standards (UNI-EN-ISO) in force at the time of the design legal metrology standards possible additional requirements for particular operational cases, such as, for

instance: minimum external temperature lower than 10 C, two or more REMIplants supplying the same distribution network.

1.7)Pressure equipment (Pressure Equipment Directive 97/23 CE)This Directive, applied by D.Lgs. n 93 of 25.02.2000 for REMI plants includes thefollowing equipments:

Primary measurement elements (meters, orifice-fitting) On-off valves Pressure regulators Safety and shotdown valve filters, exchangers and other containers.

Therefore in the design, building and testing of these equipments one has to comply with

the dispositions of the Decree mentioned above.

2) FLOW RATE, PRESSURES AND TEMPERATURES2.1)Flow rate

The flow rates, if not stated otherwise, are always expressed in m3/h at the standardconditions, i.e. in m3/h at 15 C and 1,01325 absolute bar.

2.1.1)Delivered flow rate (Qero)This is the max actual flow rate that the system can deliver.


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2.1.2)Minimum flow rate (Qmin)This is the minimum flow rate actually required by the plant.

2.1.3)Plant flow rate (Qimp)Plant flow rate is defined as the maximum flow rate for which the size of the plant has

to be determined. It is appropriate to also consider potential future enhancements.At the time of construction or reconstruction of the plant Qimp should not be lowerthan 125% of Qero.The maximum value of Qimp must allow normal operation of the REMI plant at Qmin.


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Regulation line flow rate (Qlin)This is the flow rate which regulates the sizing of the regulation line according to thefollowing scheme:

PLANTS N.LINES PARAMETERS TO DEFINE Qlin VALUE

CLEARLY INTERRUPTIBLE 1 LINE : Qlin = Qimp

NOT INTERRUPTIBLE TO SUPPLYPUBLIC UTILITY CUSTOMERS

2 LINE : Qlin = Qimp

3

CHOICE BETWEEN:

a FOR EACH LINE : Qlin 0,5 Qimpb - 3 LINES : Qtot 1,5 Qimp

with always 2 lines able tosupply

Q 2/3 Qimp.

> 3 TO BE ASSESSED EVERY TIME

NOT INTERRUPTIBLE TO SUPPLYNON PUBLIC UTILITY CUSTOMERS

2 LINE : Qlin Qimp/2

3 TO BE ASSESSED EVERY TIME

2.1.4)Flow rate off the end of the reading scale of the measurement plant (Qf.s.)This is the maximum flow rate which can be measured at the top end of the reading

scale of the measuring plant, whose value must be increased by a certain % in relationto the flow rate delivered, to allow the correct determination of the volumes actuallyofftaken.

2.1.5)Emergency flow rate (Qemergenza)The emergency flow rate is the flow rate delivered in case of emergency by temporaryequipment, and the upstream and downstream emergency valves, if present on theplant.

2.2)PressureWhere not otherwise stated, the pressure values are indicated in relative bar (o mbar).The meanings of the most useful pressure concepts are described below.

2.2.1)Maximum operational pressure (p max es)The maximum pressure the system may sustain during normal running conditions.

2.2.2)Project pressure (p pro) or (Ps)The pressure on which the design calculations are based. This pressure must be higheror equal to the maximum calibration pressure of the release device whose values aredefined in the same decree referred to in the following point 2.2.5.


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2.2.3)Minimum operational pressure (p min)The minimum pressure the system may sustain during normal running conditions.

2.2.4)Testing pressure (p col)The pressure used for the mechanical resistance test of the Main Circuit. Acceptable

values are those defined by:

MINISTERIAL DECREE 24 NOVEMBER 1984, titled "FIRE PREVENTION RULESFOR THE TRANSPORTATION, DISTRIBUTION, STORAGE AND UTILIZATIONOF NATURAL GAS WITH DENSITY NOT HIGHER THAN 0,8"

LAW DECREE 25.02.2000 N 93 IMPLEMENTATION OF THE DIRECTIVE97/23/CE CONCERNING PRESSURE EQUIPMENTS (P.E.D.).

2.2.5)Pressure for field pneumatic tightness testThe pressure used to test the tightness of the pipes and plants. It is equal to themaximum available operational pressure.

2.2.6)Upstream pressure (p mon)The pressure at the entry of any REMI. Usually the following values are identified:

The maximum value (p mon max), communicated by the Transporter whendefining the connection;

The value for preheating sizing (p mon pre) The values of minimum contractual pressure as defined in paragraph 2 of the

chapter Entry and redelivery points pressure (long period minimum contractualpressure p min L, minimum contractual pressure published yearly p min A).

2.2.7)Minimum pressure to size piping (p min P)The minimum pressure for the geometric sizing of the pipe. This value must be equalor lower than p min A and will be chosen by the designer considering theprovisions of paragraph 2 of the chapter Entry and redelivery points pressure.

2.2.8)Adjusted pressure (p reg)The pressure at the exit of the pressure regulation unit. It may be changed according tothe management needs of the plant. Its maximum value (p reg max) can be equal tothe minimum pressure to size piping and affects the sizing in terms of mechanicalresistance of the relevant part of the plant. The minimum value of the adjustedpressure (p reg min) experienced for the operations at the Qimp shall be used for the

geometric sizing.


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2.2.9)Minimum pressure to size the measurement (p min M)The minimum pressure to size the measurement main device and the pipes connectedto it. This value will be defined according to the following table:

P min Mp mon pre 24 bar The minimum value between p min A * 1,4

and 35 bar

12 p mon pre < 24 bar The minimum value between p min A * 1,4and 20 bar

p mon pre < 12 bar Equal to p min A

2.2.10)Measurement pressure (p mis)The pressure used to measure gas.

2.2.11)Downstream pressureThe pressure at the exit of the REMI plant.

2.2.12)Differential pressureThe pressure difference between the upstream and downstream intake of ameasurement diaphragm.

2.2.13)Vent pressureThe pressure for the opening of a vent valve, which is higher than the regulatedpressure.

2.2.14)Locking pressureThe pressure to close the stop valve.In the case of interruption as a result of exceeding the regulated pressure, the lockingpressure is higher than the vent pressure.

2.2.15)Nominal pressureThe nominal pressure is the conventional indication of the rel. max. pressure beyondwhich the mechanical stability is no longer guaranteed. Based on this, dimensions ofpipe elements are set such as flanges, valves, faucets.The coupling nominal pressure project pressure should be set on the basis of thecurrent rules related to the nominal pressure. As an example the schemes of thenominal pressures are provided.


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SCHEME PN (UNI-EN-1333)(Valid for operational temperature up to 120 C)

PN1 Maximum project pressure inbar 2

PN Maximum project pressure inbar

6 5 50 4910 9 64 6216 15 100 9820 19 150 14725 24 160 15640 39

SCHEME ANSI (B.16.34 1996)

CLASS Maximum project pressure in bar

ANSI For operationaltemperature up to 50 C

For operational temperature up to100 C

150 19 17300 50 46400 66 61600 100 92900 150 139

N.B. In cases where PN and the associated ANSI are not easily found in the market,the coupling should be done at the higher commercial PN or ANSI.

2.2.16) Seal pressure for the preheater and the filterThe following scheme indicates, for the most frequent max operational pressures, theminimum seal pressures required by this procedure.

Maximumoperational pressure

Bar

Minimum sealpressure

bar

1,5 25 612 1524 3060 85

64 8570 8575 85

On the containers it is not necessary to install safety devices (blowout disk, safetyvalves); unless the competent authorities expressely require it in particular cases.It is not necessary to check the sizing of such devices eventually installed.

1I valori di PN indicati sono solo quelli per i quali le Norme UNI hanno previsto l'unificazione dei varielementi di tubazione (flange, valvole, rubinetti, ecc.)2I valori sono arrotondati per difetto


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2.3)Temperature2.3.1)Project temperature

The project temperature to be considered for the sizing of the plant in terms ofmechanical resistance, are:

-10 +95 C for the part of the plant between the upstream flange of the filter and thedownstream flange of the preheater, inclusive of the possible transit pipe between thetwo devices.

-10 +50 C for the rest of the plant. In case of external temperature lower than 10 Cthe manufacturer must define the value of the minimum project temperature.

2.3.2)Temperature of the gas in entryA value of +5C is normally assumed if not otherwise stated.

3) GENERAL PROVISIONSThe plant has to assure regular running at different operational conditions, as follows:

The plant is not subjected to significant stresses other than those associated with thegas pressure

The external conditions are: temperature 10 +40 C humidity up to 95 % The noise level during the normal operation conditions should not be higher than the

limit set at the plants location

The charts to be used within this procedure are contained in attachment 10.

The REMI plant has to be built and run according to the laws and rules issued by theappropriate bodies and authorities.In addition, for the preheating plants and the pressure containers and for the electricdevices, the rules issued by the competent bodies should be followed. The electric devicesin places with fire and explosion danger should be reported to the appropriate localhealth authority (ASL) by the plant manager.

3.1)Application of the Directive 97/23/CE (P.E.D.)With reference to the content of point 1.6 all the relevant devices must comply with ECregulations and bear the EC mark as described in the same document.The article 22 (Final and temporary dispositions) of the DLgs. n 93 of 25.02.2000 defines

the application of the Directive in the case of building new plants.In addition, as far as safety devices are concerned (safety valves, monitor, blocks), theessential requirements defined in the attachment 1 point 2.11 of this Decree must besatisfied.

3.2)Detail of the general dispositionsThe general provisions for the sizing are the following:

a) It should be possible to run the measurement plant with flow rate equal to Qimp.and upstream pressure values equal to its minimum value.


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By this principle and considering that in some cases it is convenient to have thehighest downstream pressure as possible, the sizing criteria should aim tominimize the pressure losses and to assure the normal running of the plant in allthe operational conditions.

b) The plant by pass, in relation to point a), should not represent a bottleneck whichincreases the pressure losses creating utilisation problems.c) Low speed allows better regulation, lower noise and pressure losses.d) To assure an appropriate filtering (separation of the liquid and/or solid particles

present in the gas) for the safe and regular running of the operations, theseparating filters must be physically separated by the preheaters.

e) The measuring plant is made up of a main measuring system complying with thelegal metrology regulations and, if requested, by a backup system (or equipment)

to be used in case of failure of the main system or as control.The main measuring system must provide in an automatic and continuous waythe values of the volumes and of the calculated flow rates needed to carry out themeasurement, save the data on gas quantities, the diagnostic and the operationaldata. These data should be readable directly at the site or transferable by tele-reading.The plant can be made up of one or more measuring units in parallel, so that,considering the nature of the operation (wide seasonal variation in the flow rate orspecific types of offtake) and the Qimp of the plant, the flow rate offtaken alwayslies within the valid range to correctly determine the measured quantity.

f) The pressure regulation plant should not cause oscillations and pulses which maydetermine measurement errors. It is preferable to insert the possible flow rateregulation downstream of the measuring plant.

g) The downstream on-off valves of the regulation lines, if present, divide the plant intwo parts: (based on the connection of the taps of the safety devices upstream ofthe on-off valve under discussion)

The part upstream of the downstream on-off valves (inclusive), which mustsustain the maximum upstream pressure

The part downstream of the downstream on-off valves, which must sustainthe expected max. regulated pressure.

For the cases where these valves are not considered, the plant must sustain theupstream pressure up to the regulator (inclusive).

h) Usually the removable connections must be flanged (for the valves alsoconnections of the type welded flanged are accepted and for DN 4" also looseflanges are accepted). Threaded connections are accepted provided they assure theseal and the safety and resistance requirements required by the present rules. Theyshould also assure, in the case of maintenance and substitution, the functionality


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and practicability at least equal to the flanged connections and comply with thecurrent rules.

i) In general the devices should be located in a building; the standard solutionanticipates: a room for the reduction and measurement devices, a room for the

possible heating system and a room for the electrical equipment which cannot beinstalled in dangerous area.If the cabin is not built, the measurement devices should be anyway protected,therefore:

The measurement devices have to be located in appropriate rooms whichallow people to be present

An appropriate shield for the meters has to be considered.In all cases the enclosure is necessary.

4) PARAMETERS AND FORMULAS OF COMMON USEDue to the fact that natural gas is variable in its composition and that it is not necessary toobtain absolute accuracy of the parameters commonly in use to size the plants, averageindicative parameters are acceptable for this procedure and, where possible, simplifiedformulae.The formulae and parameters in the calculation for plant sizing are:

4.1)Parameters

s gas volumic mass at 15 C and 1,01325 bar = 0,70 kg/m3

Mm gas molecular mass = 16,57 g/mol

Vm gas molecular volume at 15 C and 1,01325 bar = 23,64 dm3/mol

isoentropic index = 1,31

sA air volumic mass at 15 C and 1,01325 abs.bar = 1,22541 kg/m3

gas average dynamic viscosity = 10,8 mPa.s

Pb average barometric pressure = 1 bar

P absolute pressure (bar) = p + 1, where p = relative pressure in bar

K deviation coefficient from the law of perfect gas compared to the conditions of

s;K = 1 - 0,002 p

H enthalpic overflows which can be obtained, in kj/kg or in kcal/kg, from thediagram Pressure/Enthalpy for the pure gas (see attachment 1)


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t gas temperature = 5 C, if not otherwise specified.

4.2)Formulae4.2.1)Calculation of the pipe diameter

Assuming the gas temperature equal to 5 C, the simplified formula is:

)1(*

)*002,01(**92,345

pv

pQDteo +

= where:

v = speed in m/s345,92= numeric constantQ= flow rate in standard conditions in m3/hp = relative pressure in bar, at the entry of the pipe

The theoretical diameter obtained by the above calculation must always be rounded tothe normalized diameter defined at point 5.1 applying the following rule:

DN 0,95 Dteo

4.2.2)Calculation of the pressure loss in the pipeTo calculate the pressure losses the following simplified Renouard formula valid forhigh and medium pressures and for values of Q/D < 150 should be used:

( )dp P P L Q D= 1000 25 242 1,82 4 82* , * * * , where:

dp = pressure loss in mbar1000 = numeric constantP = absolute pressure in bar, at the beginning of the pipe25,24 = numeric constantL = length of the pipe in mQ = flow rate in standard conditions in m3/hD = internal diameter of the pipe in mm

5) NOMINAL DIAMETERS TO USE - MATERIALS5.1)Nominal diameters (DN)

The most used DN are the following:

20 - 25 - 32 - 40 - 50 - 65 - 80 - 100 - 125 - 150 - 175 - 200 - 225 - 250 - 300- etc. with increase of 50 mm.

5.2)MaterialsD.M. 24.11.84 definitions apply.


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6) TYPES OF ON-OFF VALVES TO BE USEDThe different types of valves, according to their location, are:

a) From the delivery point to the valves upstream of the filtering unit ball valves orconic plug valves must be installed.Ball valves can also have venturi passage with ratio between the passage diameter

(d) and the diameter (DN) of the valve 60%.

b) Upstream and downstream valves for the preheating unit and/or of the regulationunit should be as indicated in a).

c) The on-off valve of the blowdown valve must be a ball valve with full passage.d) The on-off valves of the measuring plant and of its by-pass must be ball valves

(with full or venturi passage as in a) or butterfly valves, with the exception of the

valve upstream of the venturimetric section which has to be a ball valve with fullpassage.

e) Exit valves should be as indicated in d).f) For all other possible valves, the type will be defined on the basis of their function,

consistent with the above criteria.

7) SIZING AND MAIN FUNCTIONAL INDICATIONSThe plants will be designed following the flow schemes contained in Attachment 3.The quantity and location of the valves, of the equipment and pressure and temperatureintakes must be, in their minimum configuration, that described in those schemes. Theymay be increased in number only to improve the plant functionality.To simplify the check and design operations, the sizing criteria described do not take intoaccount the pressure losses through the plant, assuming that in most cases this omission isacceptable.For the plant resistance, the principles defined in the chapter General Criteria and theinformation supplied in the chapter Pressures apply, except for what is specified in thefollowing points.

7.1)Diameters and maximum operational pressures of the valves, of the pipes (includingthe manifolds) and of connected equipments

The valves must have the same DN of the pipe where they are inserted.Every section of pipe must have uniform diameter.The DN must be calculated from the theorical diameter according to the rule in point4.2.1.The theoretical diameter must be calculated in such a way that the speeds indicated in thefollowing scheme should be respected with the specified flow rate and minimum pressurevalues.In the following scheme the maximum operational pressure values are indicated to definethe project pressure relevant for the mechanical resistance of each component of the plant.


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The details in the following points apply to the geometric sizing and in terms ofmechanical resistance.For the parts of the plant not included in the scheme, the general criteria already definedapply.Regarding the number and the location of the insulating joints the present procedure

assumes that REMI entry and exit sections are not underground, while the upstream anddownstream pipes of such sections are underground.


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PARAMETERS TO SIZE THE DIAMETERS

SIZING PRESSURESECTION Vmax

m/s

Flow

rateQ

Measure withregulated p.

Measure withvar. p.and t.

NOTE

1 Upstream section 30 Imp p min P p min P Complying with point 7.2

2 Pipes, valv. filterFILTER

30 Lin p min P p min P DN filter DN pipe

3 Pipes, valv. Preheat.PREHEATER

30 Lin p min P p min P DN preheat.. DN pipe

4 Pipes, valvesupstream 1 regulatorREGULATOR

30 Lin p min Pp min P

DN upstream regulatorDN

5 Pipes and valv.

Downstreamregulators 25 Lin < p min P < p min P See point 2.2.8

6 Manifold downstreamregulators

25 Imp < p min P < p min P See point 2.2.8

7 Valv. feed. And exitmeasure. lines

25 Imp < p min P p min P See point 2.2.8

8 Pipes downstreamand upstream entryand exit valvesmeasure. lines

25

30

Imp

Imp< p min P p min P

See point 2.2.8

9 By-pass pipes andvalves

measure lines30 Imp < p min P p min P See point 2.2.8

10 Pipes and valvesseries parallel

25 Imp < p min P p min P See point 2.2.8

11 Pipes. Meter linesMETERS 25 Ero

p mis

( p min P)p min M Complying with 8.2

12 Pipe venturimetr. line25 Ero

p mis

( p min P)p min M Complying with 8.3

13 Manifolddownstream filters

30 Imp p min Pp min P

14 Manifold upstreampreheating

30 Imp p min P p min P

15 Manifold upstreamregulators 30 Imp p min P

p min P

16 Exit section 25 Imp < p min P < p min P See point 2.2.8

Pressures:

p min P minimum pressure to size pipingp min M minimum pressure to size measurep mis measure pressure


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PRESSURE TO SIZE THE MECHANICAL ENDURANCESECTION

Measure withregulated p.

Measure with var.p.and.

NOTE

1 Upstream section p mon max p mon max

2 Pipes, valv. filterFILTER

p mon max p mon maxFor the pressure containers,

see point 2.2.15

3 Pipes, valv. Preheat.PREHEATER.

p mon max p mon maxFor the pressure containers,

see point 2.2.15

4Pipes, valves

upstream 1regulatorREGULATOR

p mon max p mon max

5Pipes and valv.Downstream

regulators

p mon maxp min P

p mon maxp min P

Up to the 1st valve in the gasdirection

After the 1st valve in the gas

direction

6Manifolddownstreamregulators

p mon maxp min P

p mon max

Up to the 1st valve in the gasdirection

After the 1st valve in the gasdirection

7 Valv. feed. And exitmeasure. lines

p min P p mon max

8Pipes downstreamand upstream entryand exit valvesmeasure. lines

p min P p mon max

9By-pass pipes andValvesmeasure lines

p min P p mon max

10 Pipes and valvesseries parallel

p min P p mon max

11 Pipes. Meter linesMETERS

p min P p mon max

12 Pipe venturimetr. line p min P p mon max

13Manifolddownstream filters

p mon max p mon max

14Manifold upstreampreheating.

p mon max p mon max

15 Manifold upstream

regulatorsp mon max p mon max

16 Exit section p min P p min P

Pressures:

p min P minimum pressure to size pipingp mon max maximum entry pressure


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7.2)Upstream sectionThis is the section between the delivery point and the upstream filter manifold, the latterand possible upstream emergency valve included.The general upstream on-off valve of the REMI plant (1st valve in the direction of the gas

downstream of the delivery point) must be located as close as possible downstream of thedelivery point.The pipes must have uniform diameter and such dimension as to satisfy the followingcondition:

a) gas speed must be 30 m/s.

To calculate the speeds the formula at point 4.2. can be used, where:

Q = Q plant in m3/hP = Minimum pressure to size piping (p min P)

The (optional) upstream emergency valve must be installed outside the room in thesection between the general on-off valve and the next on-off valve/s.Usually it is located downstream of the upstream insulating joint and must be electricallyisolated if it is by-passed from underground pipe protected by current.The valve and the connected pipes must be sized to allow the supply of the flow rate incase of emergency.

7.3)Filtering unitThe filters must be efficient enough to hold both the liquid and solid particles present inthe gas.

In addition the filters must have such a filtering capacity as to assure the normaloperations of specific equipment downstream of the same filter (es. regulator, meters, etc.)with Qimp.

7.3.1)Filter with condensate separator The filter can be made up by two separate stages (solid and liquid particles). The filtering element must be changeable. The minimum filtering capacity must be equal to:

98% of the solid particles 5 micron100% of the solid particles 10 micron95% of the weight of the carried liquid particles.

The collection capacity should be no lower than 12% of the total capacity of thefilter and shouldnt impact the gas flowing zone to avoid obstruction.

The pressure loss through the clean filter should not be higher than 0,1 bar withflow rate equal to Qlin, with pressure equal to a p min P.The manufacturer must declare this deltapi

The filter must be equipped with an indicator of the pressure loss between entryand exit (dpI), with on-off valves and possible by-pass.

The DN at the entry and exit of the filter should not be lower than the DN of thepipes connected to it.

A full size quick closing is recommended to substitute the filtering element inshort time.


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s = gas volumic mass at 15 C and 1,01325 bar 0,7 kg/m3prer = preheater efficiency 0,9Q = maximum line flow rate in m3/h in standard conditionsh = enthalpic overfall in kcal/kg equal to the difference between gas

enthalpy at Pv - tv conditions and gas enthalpy at Pm - Tm conditions(to be obtained on the basis of the scheme in attachment 1).Pm = absolute upstream pressure to size the preheatingtm = 5 C (average value) = delivery temperaturePv = minimum absolute pressure foreseen downstream of theregulator (p reg min)tv = temperature downstream of the pressure regulator.

If the capacity C is expressed in kw and the entalphic overfall h is expressed in kj/kg,the previous formula becomes:

QhC **000216,0=

NOTE: This procedure deals specifically only with the cases of hot water preheatingplants, since they are the most frequently used.Operational temperatures even higher than those indicated may be reached ifusing different preheating plants (which may be used, if complying with therules in force). In this case, the sizing in terms of mechanical resistance shouldtake into account the necessary correlation between temperature and pressure.

7.4.2)Thermal capacityThe total capacity of the thermal plant in kcal/h is obtained by the formula:

Mh Q

risc prerh Q

s= =* *

*, * *

0 86

where:

Q = max plant flow rate in m3/h = Qimp

risc = coeff. rid. efficiency boiler 0,9Other symbols = same meaning as in 7.4.1.

If the capacity M is expressed in kw and the enthalpic overfall h in kj/kg, the previousformula becomes:

M h Q= 0 00024, * * It is advisable, for safety and operational continuity reasons, that the total thermalcapacity should not be provided by just one boiler, but should be distributed at leastbetween two boilers working in parallel.

7.4.3)Reduction unit feeding the heating systemThe unit has to be installed in the room or the area of the reduction (and measurement)equipment.


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The feed must be shunted downstream of the measure, with steel valve, able to sustainthe maximum operational pressure (usually the measurement pressure).The reduction unit has to be made up of:

A pressure reducer A safety valve which avoids, in case of failure of the reducer, the maximumpressure defined downstream being exceeded.The two elements, which may be integrated in just one device, may have the casing in

spheroidal iron or other suitable materials if the maximum operational pressure is 5bar.In all other cases the casing should be made of steel.It is advisable that a backup unit is installed; in this case on the main unit, a stop valvecan be inserted in the regulator, as an alternative to the safety valve. In this case on theemergency line the monitor (incorporated or not) may be installed, instead of thesafety valve.

7.5)Regulation plantThe regulation plant is made up by the ensemble of valves (monitor, regulator, block) andpossible additional equipment such as pilots, pressure taps, service regulators, connectionsmall pipes, safety and relief valves. The sizing criteria for the valves are provided.The calibration value has to be chosen considering the maximum acceptable pressurevalue in the downstream network.The pressure regulation plant should allow a regulated pressure to be obtained with amaximum variation versus the calibration value equal to 10%. If the measuring plant is

not automated this variation is limited to 2,5%.For each regulation line the pressure reducing valve and the monitor can be two different

valves, in series on the same pipe axis and with the same size characteristics (theconnection between the two valves will be that provided by the manufacturer), or a singlevalve with the two functions.The use of fail to open regulating valves with monitor function is not allowed.The monitor has to be marked EC as safety device complying with D.Lgs. n 93 of25.02.2000.


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7.5.1)Design FormulaWith (P1 - P2) < 0,456 P1 (not in critical overfall)

gradi

P

PP

CPCgQ

= 121

*1

3417

sen*1**55,0

With (P1 - P2) 0,456 P1

Q Cg P= 0 55 1, * *

where:

Q = flow rate of the valve m3/hCg = characteristic coefficient of the valve

P1 = upstream absolute pressure of the valve barP2 = downstream absolute pressure of the valve barC1 = ratio between Cg/Cv coefficients, where Cv is the

liquid coefficient of the valve. If the value of Cg isunknown, but Cv is known, assumptions will be C1 =30 and therefore Cg = 30 Cv.

7.5.2)Values of Cg and C1The values have to be officially declared by the manufacturer and usually arepublished in the technical specification of the manufacturer.In particular cases if the Cg and C1 values are not available, the following values may

be used for an indicative calculation:C1 = 30

2*6540.0 DNCg = for DN up to 150 included

CgDN

DN=

+

0 654

1150

250

2, *

for DN higher than 150

If the regulator is provided with a muffler and the manufacturer doesnt define clearlythe resulting Q reduction, the known Cg is multiplied by 0,9.

7.5.3)Values of P1ande (P1 - P2)The P1 value to insert in the formulae is usually the project minimum absolutevalue (p min P + 1).The value of (P1 - P2) will be equal to (P1 - P reg min), with (P1 - P reg min) higher orequal to the minimum dp established by the manufacturer and lower than 0,456 P1 (inthe particular cases with minimum upstream pressure equal to 0,15 relative bar, il dp

will be set equal to a 40 mbar). With (P1 - P reg min) 0,456 P1, the calculation

formulas dont require the value (P1-P reg min).


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P reg min is the minimum regulated pressure value foreseen for the operations atQimp.

7.5.4)Choice of the regulatorThe regulator to be chosen is the one as results from the calculation - able to provide

a flow rate Qlin.The calculation should be performed using the formulas A or B, the Cg and C1 valuesdescribed at 7.5.2. and P1 and (P1 - P2) values described at 7.5.3.

7.5.5)Choice of the monitor (if separate)The monitor should have the same dimension characteristics of the regulator describedat 7.5.4.

7.6)Relief valveThe aim of the relief valve is to avoid the increase in the regulated pressure which canhappen in case of closing failure both of the regulators and monitors. As an alternative, a

valve can be installed on each regulation line, or a single valve can be installeddownstream of the manifold.

In the case where the relief valve is installed downstream of the downstream on-off valve,it is mandatory to install, downstream the relief valve, a spherical on-off valve with fullpassage, sealed with lead in opening position, with DN and PN equal to those of the reliefvalve.

The relief valves must be marked EC as safety devices complying with D.Lgs. n 93 of25.02.2000.In the cases where this D.Lgs. allows the installation of qualified valves, in accordance

with ISPESL rules, these should have the value of the coefficient of efflux Kexperimentally determined according to predefined criteria.In the description of the device must be included:

The net area "A" of the orifice of the valve cm2 the coefficient of efflux K resulting from the ISPESL qualification tests.

The theoretical diameter "dteo" must be equal to 1/10 of the diameter of the pipe fromwhich it is shunted the pipe on which the same is installed.The formulas to be used are:

dteoA k

=4 * *

( )A

dteo

k=

*

*

2

4

Based on the calculated value of A, the equal or immediately higher value, available inthe market, is to be found.


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8) MEASUREMENT PLANTThe measurement plant is made up of the ensemble of devices and tools installed asmeasurement, backup and/or control as well as the piping needed to by-pass the gasflow.

The primary element has to be designed to allow a valid measurement within the rangeQero Qmin.The measurement plants have to be realized in accordance with the general criteriapreviously defined, as indicated at point 7.1., and complying with the technicalattachments to the present procedure.

8.1)Allowed equipment and type of pipingThe equipment and type of piping allowed for the measurement plants are indicated forflow rate ranges Qero in the attached table (attach. 2). The standard schemes, as indicatedin attach. 3b, are defined in accordance with these tables.The flow rate ranges under consideration in m3/h based on the type of the measurement

primary element are the following:

MEASUREMENT WITH METERMEASUREMENT WITH VENT.

DIAPHRAGMQero < 4000 12000 Qero < 30000

4000 < 30000 30000 < 6000030000 60000

The main criteria to define the characteristics of the metering plant are the following:

a) The main measuring system must be automated with electronic data processingdevices (flow computer). The m3/h and m3/d data needed for fiscal reasons mustbe saved (current and previous month) and transferred by telereading (switchednetwork or GSM) according to the standards defined by the transporter. Besides,in some cases, the back-up and control equipment are required to determine, in anon automatic way, the gas quantities.

b) The electronic data processing devices (flow-computers, calibrators, PTZ) mustcomply with:

Legal metrology provisions in force on the subject issued by EEC Directiveand national laws

CEN rules specific for this product, currently only the EN 12405 Electronicvolume conversion device associated with gas meters

ISO international rules concerning the formulae to calculate the flow rates andquantities in volume and energy.

c) For values of Qero < 12000 m3/h the measurement by venturimetric diaphragm isnot allowed.

d) The measurement by meters is allowed for every value of Qero.


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e) If the meter with a Qmax designed on the basis of Qimp is not able to measure theminimum flow rate offtaken (e.g.: seasonal variations) it is necessary to install ameter with lower Qmax , indipendent and in parallel with the 1 meter.

f) For Qero 4000 and < di 30000 m3/h a second meter equal to the first one has tobe installed as back-up.The second meter, if the case e) applies, can be of a lower class provided a by-passcommon to the two meters be installed.

g) For Qero 30000 m3/h the piping of the plant with meters, of the same gauge,must allow connection in series.

h) For Qero 30000 m3/h in the plants with two or more meters (of the same gauge)every meter has to be connected with an automated measurement chain (flow ratecalculator and transmitters).

i) For Qero 60000 m3/h in the venturimetric plants the automated measurementchain (transmitters, flow rate calculator) must be duplicated (see attach. 2).

8.2)Measurement with metersThe volumetric meters (with expandable walls, rolling pistons, turbine) must comply withthe legal requirements, the performance and the functional characteristics defined in thefollowing documents:

National metric rules EEC Directives concerning the gas meters:

DPR n 857 of 23 August 1982 (71/318, 74/331, 78/365)

Decree 9 September 1983 and subsequent modifications UNI-CIG 7987/7988 provisions ISO 9951 provision EN 12480 EN 12261 provisions.

In accordance with what the above laws and rules define, the meter should be equippedwith metric seals, plate with all the data (Qmax, Qmin, pmax, impulses/m3, ecc.) and thecertificate with the calibration curve. The meters made in other EEC Countries must showon the plate the EEC mark with the approval number of the model.The meters should be equipped with two pulses emitters with characteristics complyingwith the above rules.

8.2.1)Choice of a metera) The meters that can be installed should comply with the above requirements, and

assure as minimum value a measurement range with ratio Qmax/Qmin not lowerthan 20:1.

b) The maximum operational and measurement pressure connot be higher than themeters Pmax .


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c) The meters with casing made up by material different from steel (spheroidal castiron, aluminium) may be used with the limits defined by DM 24.11.84 as far as themaximum operational pressure and nominal diameter are concerned.

d) To define the Qmax of the meter to be installed, the following steps should befollowed:

d1) Calculate the maximum theoretical flow rate with the following conventionalformula:

( )1*05,1max

+=

p

QerotQ

where:Qmaxt = theoretical maximum flow rate m3/hQero = flow rate delivered (max effective flow rate that the plant must

deliver)1,05 = increase coefficient equivalent to approx 5% compared to Qerop = relative measurement pressure in bar, according to the cases

p reg for the plants at regulated p and tp min M for the measurement plants at pipeline p and t

d2) Identify the meter with Qmax, based on the following table, equal orimmediately higher than Qmaxt calculated as above.The Qmax values are unified, however the manufacturers may providedifferent DN for the same Qmax, or provide no meter with particular Qmaxvalue. This last case may reduce the choice.

Qmaxm3/h

DNmm

Vm/s

Qmaxm3/h

DNmm

Vm/s

Qmaxm3/h

DNmm

Vm/s

25 4050

64

400 80100150

22146

6500 300400500

26149

40 4050

96

650 100150200

23106

10000 400500600

221410

65 40

50

14

9

1000 150

200

16

9

16000 500

600

23

16100 40

502214

1600 150200250

25149

25000 600 25

160 5080

239

2500 200250300

221410

250 80100

149

4000 250300400

23169


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e) The pulse emitters may be low frequency if Qmax is 400 m3/h. For higher flowrate at least one should be high frequency.

If a signal (420 mA) is needed of the instantaneous flow rate a high frequencyemitter should be preferred independently of Qmax.

NOTEThe ratio Qmax/Qmin of the turbine meters is variable, because, remaining constantQmax, Qmin changes in function of the square root of the gas density at the lineconditions. The minimum flow rate in m3/h at the operational conditions isapproximately given by the following formula:

Q pQ

pmin( )

, * min=

+

1 32

1

Qmin(p) = Minimum flow rate m3/h at the operational pressure "p".

Qmin= Minimum flow rate reported in the meter plate (metrologicallyapproved)

1,32= d

1

where d = relative density (0,57392).

8.2.2)Diameter of the rectilinear sections directly connected to the metersThe DN of the pipe of the rectilinear sections (excluding the valves) upstream anddownstream the meter, must be equal to the meter DN.

8.2.3)Lengths of the rectilinear sections directly connected to the metersAssuming as DN that of the meter needed to calculate a Qero = Qimp , the minimumlengths to be complied with are:

a) Upstream sectiona1) For turbine meters: 10 DN1

The length can be reduced to a 5 DN if a meter with integrated flow rectifier isinstalled, in this case the manufacturer should document the result of the testscarried out in the ways defined in EN 12261 (Annex B) rule.

a2) For meters with expandable walls, with rolling pistons: 5 DN1b) downstream section

for all types of meter: 2 DNIt necessary to provide after the 2 DN enough room to insert the two thermometerpockets, to measure and control.

1Per i contatori a parete deformabile od a turbina radiale non risulta necessario alcun tratto rettilineo.

Per cui se il contatore installato quello relativo a Qimp i tratti rettilinei non sono necessari.


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8.2.4)By-pass of the on-off valve upstream of the meterOn the measurement line with meters with DN 150 it is advisable to install a by-pass(DN 25 50) to use in the starting operations, avoiding to damage the meter.

8.3)Measurement with venturimetric diaphragm

This measure can be performed if the following 3 conditions occur at the same time:

Value of Qero 12000 m3/h DN of the measurement section 100 Measurement section 2 bar

The plant must be carried out in accordance with UNI EN ISO 5167-1/A1 rules, theprovisions hereunder indicated and possible rules defined by following legal metrologyregulations.The gauging certificate of the measurement diaphragm should comply with attach. 5. andthe dimension check in accordance with these rules should be carried out by an

appropriate Institute. The exact dimension of the inside diameter of the pipe should bereported with the gauging report as defined in attach.It is advisable for accuracy reasons, both for equipment reasons and for the limits set byReynolds number, that the minimum flow rate Qmin offtaken should be lower thanapproximately 5 % of the F.S. Q. In fact, at that Qmin value corresponds a differentialpressure value equal to 1,25 mbar (measured by the low deltapi transmitter with f.s. 100mbar). If the plant Qmin is lower than these percentages, better solutions should beidentified to measure the low flow rate, for instance by installing more measurement lineswith automated insertion.

8.3.1)Measurement lineInformation relating to the whole measurement line is:

a) Throttling devicesPrimary elements made up by diaphragm-holder of the type "Orifice Fittings" withpressure taps on the flanges are allowed.

These devices allow:

A better functionality and operational easiness which reduce significantly thetime needed to substitute or check the diaphragm

Improved ease to center the diaphragm and therefore greater guarantees ofbetter measurements.

b) Lengths of the rectilinear sections of the venturimetric sectionb1) Upstream section

For Qimp < 30000 m3/h L 30 DN

For Qimp 30000 m3/h L 50 DN


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b2) Downstream sectionIn all cases L 8 DN

The DN to consider, to define lengths, is the one that, in accordance with the table at

the following point, allows the measurement of a Q = Qimp with speed 25 m/s andwith:

Measurement p = p reg min (always < p min P) for plant at regulated p and t Measurement p = p min P for the measurement plant at pipe p and t.The values indicated are valid until new legal metrology criteria are introduced.

c) Pipes allowed for measurement linec1) Type of pipes according to the manufacturing process

Obtained by weldless cold-drawing (preferred) Obtained by weldless hot-drawing By longitudinal welding.Different types should be analyzed case by case.

c2) Inside wall conditionInside walls must be clean, without corrosion and scaling, even if localized infew points. The presence of a slight rust film is allowed.

d) DN of the pipe to be installed and value of the ratio between diametersThe DN project calculation is carried out according to point 7.1, complying withthe limit hereunder indicated and applying the flow rate calculation formulaindicated in UNI EN ISO 5167-1/A1 rule.

value(ratio between diameters d/D):

with DN 100 mm: 0,10 0,7 if the lenght of the upstream section is > 40 DN, a value of up to a maximum

of 0,75 is allowed.

8.3.2)Lay-out of pipes and devices in thel "entry section"A plant section defined as entry section is a plant section upstream of the rectilinearsection upstream of the metering line. It should be realized in accordance with thefollowing points:

a) Once defined a reference plan (horizontal or vertical) along the axis of themeasurement section, the entry section, located in the reference plan for a totallength 10 DN (point 8.3.1.c), can be made up by a single pipe, or a pipe, elbowsand/or valves and/or other devices in accordance with the following points.


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b) The gas flow in the "entry section" must always remain, even changing direction,in the same reference plan defined in a). Therefore it shouldnt be installed in theentry section:

Elbows and T part on plan different from the reference one Any other device which causes a plan change,

compared to the reference plan, in the gas flow.

c) In the "entry section it is forbidden to install: Any regulation valve Any expansion in the diameter with ratio higher than 0,5 to 1 of the DN of the

measurement section (the expansions must have length DN of themeasurement section).

d) The on-off valves in the "entry section" should be of the type described in point 6d.e) If the upstream rectilinear section has a length 50 DN the limits set in c) and d)

do not hold and besides the rectilinear sections mentioned in a) may be ondifferent plans and of the total length strictly necessary to connect the devices orspecial parts or elbows.

f) The cases clearly different from those here described should be analyzed case bycase.

8.3.3)Measurement equipment and devicesThe equipment and devices necessary in relation to Qero are defined in attachment 2.The ends of the reading scale of the differential pressure are:

High deltapi 500 mbar Low deltapi 100 mbar

It should be foreseen pressure taps, deltapi (on the diaphragm) and thermometerpocket to carry out checks in the field.All the thermometer pockets should be inserted downstream, after the gli 8 DN, on theupper generatrix of the pipe.

9) EXIT SECTION9.1)Exit valve

The last downstream valve, in the gas direction, is described in attach. 3b and 3c.Practically this may not occur. Therefore the conditions defined in 9.2 and 9.3 should besatisfied, remaining valid the design criteria above defined until the exit valve.

9.2)DN of the pipe

The pipe of the exit section should have a DN to assure a speed 25 m/s.


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9.3)Downstream emergency valve (optional)This valve should be installed outside the room, at the exit section, upstream ordownstream of the exit valve. It may be located upstream or downstream of thedownstream insulating joint and should be electrically isolated if shunted byunderground pipe shielded by current.

The emergency valve should be sized in order to be able to easily supply the emergencyflow rate.

9.4)Check valveIf the plant configuration or the system operations cause possible gas backflows, it isnecessary to install in the exit section a check valve.

10) PERFORMANCE CRITERIA10.1)Foreword

In this chapter the main criteria to follow in assembling and installing the receiving andfirst gas reduction plants are described.The assembling and installing of the pre-heating plant (boiler, pipes), not considered inthis chapter, should be carried out in accordance with the building and installation rulesof the heating plants, applying for the boiler the safety requirements foreseen by the lawsin force.

10.2)General priciples10.2.1)Safety and easy of access

The design should consider in particular the safety factor.The accessibility to all the equipment of the plant should be assured and any point

should be reachable by the relevant tools. An easy exit from the plant should beassured in case of emergency.

10.2.2)Assembling and installingThe assembling and installing should not cause additional mechanical stresses besidesthose produced by the gas pressure.The special parts, the equipment and the pipe sections should be manufactured andinstalled in such a way as to comply with the criteria of verticality, horizontality andparallelism.

10.2.3)Cabin buildingThe walled cabin should be built and tested in accordance with the rules issued by thecompetent authorities regarding the buildings as well complying with D.M. 24November 1984 "SAFETY RULES FOR THE TRANSPORTATION, DISTRIBUTION,STORAGE AND UTILIZATION OF NATURAL GAS WITH DENSITY LOWER THAN0,8".

10.2.4)MaterialsThe provisions of the same D.M. apply also to the materials. The pneumatic joints forthe devices, impulse taps and relief of the regulating tools must be made by stainlesssteel. For inside diameters not greater than 10 mm, they can be also made of copper.


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10.3)Pipes, flanged connections, special parts, releasesAs a rule pipes should be layed above ground or should in any case be inspectable.Underground laying is only allowed for the pipes connecting the general on-off valvesand the plant. At the installation the pipes, the connections and the special parts must beperfectly internally clean. In building the piping it should be used only special parts such

as: elbows, tees, weldolets, flanges, made by materials and dimensions complying withappropriate standards (ASTM, ANSI, API, MSS, etc.).The gaskets should be made in material resistant to effect of gas and to possible odorizingsubstances.In accordance with D.M of 24.11.84, for the safety valves and the release devices in theatmosphere appropriate vent pipes should be prepared to let gas in the air at appropriateheight (not < to 3 m from the field), not affecting the openings of the possible boiler room.In particular the end part of the releases should be made in such a way as to let the gasvent bottom-up and to prevent rain infiltration.

10.4)Welding

Welding should be carried out by qualified welders and with processes qualified byappropriate and officially recognized institutions.Contiguous weldings between pipes along the axis with distance lower than 1,5 D (with aminimum limit of 60 mm) should be avoided.

10.5)Installation of the devicesFor the installation of the devices and possible pneumatic joints the indications of themanufacturers should be respected as well as these criteria. Easy control and calibrationshould also be assured.

10.5.1)Separating filters and preheatersBetween lines should be left enough room to let the maintenance operations to beperformed.If the inspection and maintenance of the filters is not allowed by the free space, aservice platform should be considered. The drainage of the devices should beseparately carried outside of the possible cabin and in such a position as to assure themaximum safety and the easy collection of possible inpurities.

10.5.2)Regulation plantsBetween lines should be left enough room to let the maintenance operations to beperformed.The appropriate actions should be taken in order to assure in any moment the

continuity and regularity of the operations (e.g. pre-heating or tretment of the gasfeeding possible additional devices such as service regulators and pilots).Devices by-passing the regulators are not allowed.

10.5.3)Measuring devicesGeneral principlesThe measurement devices and the primary elements should be installed in such aposition as to assure an easy access and to easily allow the data collection, the controland calibration operations.


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If, for specific reasons, it is necessary to install measurement devices in the open air(transmitters, recorders, calibrators, etc.) they should be shielded within appropriateprotections such as: boxes, cabinets, containers.These protections should be made by appropriate materials, with such dimensions andin such a way as to avoid temperature variations outside the limits defined by the

manufacturer.

Measurement venturimetric sectionThe measurement venturimetric section should be installed in accessible position, if

possible at a height from the field not higher than 1 1,20 m .

MetersThe meter has to be installed in such a way as to avoid any mechanical stress causedby the upstream and downstream piping and according to the manufacturersinstructions.If requested, the lubricating oil must reach the set level, and be verified by suitable

lamp.The meausrement pressure has to be taken by the appropriate tap Pr present on themeter.In the case of meters with expandable walls and rolling pistons even if provided withtap Pr, the operational pressure can be measured upstream of the upstream rectilinearsection of the meter.

10.6)Painting and insulationThe piping and all the devices should be protected against corrosion by an appropriatepainting cycle.Insulation is recommended on the heat exchangers, on the water circuit and on the

measurement section.

10.7)Electrical systemsThe gas reduction and measurement plants are locations with the potential for explosionsdue to the presence of inflammable gas where the electrical systems (from the 1st of July2003, also other systems which can represent primer source) must comply with particularsafety requirements.

The definition of the area with explosion danger should be made in accordance with thecriteria set in the CEI EN 60079-10 (CEI 31-30) rule and in the 1999/92/CE directive.To design the electrical system, the installation and choice of the protection according to

the three types of area (0,1,2), should comply with CEI EN 60079-14 (CEI 31-33) rule and94/9/CE directive.

Regarding the electrical material to be used, in 1994 the CEE 94/9 directive has beenissued, received by D.P.R. n126/98, aiming to define for all products, electrical and nonelectrical, to be installed in the EU Countries, the essential requirements for the utilizazionzone. This directive will substitute the previous ones (76/117/CE; 79/196/CE) startingfrom the 1st of July 2003. The electrical devices with compliance certifications issued onthe basis of old directives may be installed until and no later than the 30th of June 2003.


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According to the law n.46/90, such electrical systems should be designed by aprofessional belonging to the register within his competencies, and the works ofinstallation, transformation, expansion and extraordinary maintenance should be carriedout by qualified companies, or in the case of non installing companies, by the internaltechnical departments which at the end of the works issue appropriate statement of

compliance of the system to the standards.

Such electrical systems, the grounding system, and possible devices against atmosphericdischarges have to be set at work, approved and verified in accordance with D.P.R. 22October 2001, n 462.

The check of the need of a device against atmospheric discharges has to be carried out inaccordance with CEI 81-4 rule or, where applicable, CEI 81-1 rule. If the protection systemhas to be provided, the provisions contained in CEI 81-1 apply and, where foreseen byD.P.R. 26.5.59 N.689, it has to be communicated to ISPESL.

10.8)Protection of the undergroung pipes against corrosionThe metallic pipes should be coated against damage caused by the ground where thepipes are laid and the corrosion caused by possible natural or leaked electric currents.In presence of natural or leaked electric currents, besides an efficient coating, a cathodicprotection is recommended.These systems should comply with the legal provisions (D.M. 24/11/1984) and with thetechnical rules in force.

10.9)Criteria for the pneumatic connections of the measuring devicesSee attachment 8.

10.10)Criteria to install computerized measurement systems

See attachment 9.


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INDEX OF THE ATTACHMENTS

Attach. 1 DIAGRAM PRESSURE ENTHALPY FOR THE NATURAL GAS (2pages)

2 MEASUREMENT PLANT WITH FISCAL VALUE (1 page)

3 STANDARD SCHEMES FOR "REMI PLANTS" AND DESCRIPTIONOF THE DEVICES

3a - regulation plant (5 pages)3b - measurement plant with fiscal value (9 pages)3c - REMI plants with variable pressure and temperature (4

pages)

4 MAXIMUM ALLOWED ERRORS IN THE MEASUREMENT SYSTEMS

(1 page)

5 DIAPHRAGM GAUGING CERTIFICATE (1 page)

6 GAUGING OF THE MEASUREMENT SECTION (1 page)

7 REMI PLANT WITH UPSTREAM P max 5 bar (6 pages)

8 CRITERIA TO CARRY OUT THE PNEUMATIC CONNECTIONS (6pages)

9 CRITERIA TO INSTALL COMPUTERIZED MEASUREMENTSYSTEMS (5 pages)

10 CARTHOGRAPHIC DOCUMENTATION FOR PIPELINES (15 pages)


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ATTACH. 2 - MEASUREMENT PLANT WITH FISCAL VALUE

SYMBOLS:V = provides a final value for flow rate and/or vol.M = belongs to the measurement chainR = back-up and controlC = control

Vol Qero < 4000 X

Vol. 4000 Qero < 30000 XVol. 30000 Qero XVent.12000 Qero < 30000 XVent.30000 Qero < 60000 XVent.60000 Qero X

DEVICES TYPE OF MEASUR.PLANT

DESCRIPTION ABBR. 10 30 40 60 61 62

1 Meter FT M M M2 P and T indicators PI,TI R C C C C C3 Manotermograph PR,TR R R4 II Meter Series/Parallel IIFT R R5 Venturimetric section FE M M M6 Type 1 calculator RK V7 Type 2 calculator FF+FP V V V V V

8 2 Type 2 calculator FF+FP R V9 Telereading module TEL V V V V V V10 P Transmittiter PT M M M M M11 T Trasmittiter TT M M M M M12 High dp transmitter HdpT M M M13 Low dp transmitter LdpT M M M14 Gaschromatograph or RHOS transmitter GC o GT M M15 E lectric recorder of RHOS and/or Q eGR/eFR R R16 Multivariable transmitter (Q-dp-p-t) (5) MT R R

NOTE 1 4 2 2 3 2 34

NOTES:

A type of plant with higher performance is always allowed.

1) For Qero < 4000 the installation of back-up and control measurement isrecommended.

2) For Qero 30000 a gas chromatograph (or in alternative the densimeterRHOS) has to be installed. This device is recommended for Qero between12000 and 30000. The gas chromatograph should be installed as indicated inthe Attachment 11/B of the chapter Gas quality of the Network Code. Ifpermitted by the legal metrology, the direct connection between the gaschromatograph and the computer is possible.

3) The signal (4 20 mA) of Q must be recorded when the measurementpressure is, or may be, variable. The signal 420 mA of Rhos must always berecorded.

4) The devices from pos. 10 to pos. 16 must be duplicated in function of the 2ndcalculator.

5) Device substituting the deltapi indicator and the 3 peen mechanical recorder.This transmitter calculates Q; it displays the values Q-dp-p-t-; it stores thesame values with hourly frequency for 45 days.


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ATTACH. 3 - STANDARD SCHEMES FOR "REMI PLANTS" AND DESCRIPTION OF THEDEVICES

ATTACH. 3A REGULATION PLANT

SUMMARY SCHEME

TYPE OFCUSTOMER

PRESS.PREHEA

T.TYPE

CHARACTERISTICSREGULATION LINES

NOTINTERRUPTIBLE

Pubblic Utility > 12 A Min. 2 lines (F,P,M,R) Qlin Qimp

Pubblic Utility 12 B Min. 2 lines (F,M,R) Qlin QimpNot Pubblic Utility > 12 A Min. 2 lines (F,P,M,R) Qlin 0,5 Qimp

Not PubblicUtility

12 B Min. 2 lines (F,M,R) Qlin 0,5 Qimp

INTERRUPTIBLE

> 12 C LINE (F,P,M,R) Qlin Qimp

12 D LINE (F,M,R) Qlin Qimp

As an alternative to the monitor it may be installed: block valve (upstream of the regulator) orblock valve incorporated in the regulator.The choice of these alternatives will be made by the designer assessing the operationalconditions foreseen in the downstream network, especially in particular cases (e.g. more remi

plants connected in parallel.

F = SEPARATING FILTER P = PREHEATER (heatexchanger)

M = MONITOR R = REGULATOR


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REGULATION PLANT NOT INTERRUPTIBLE

p mon pre. > 12 BAR

TYPE A

POS. DESCRIPTION POS. DESCRIPTION

1 Enbloc Insulating Joint 12 Pressure indicator2 On-off valve 13 On-off valve3 On-off valve 14 On-off valve full passage4 Blind flange 15 Direct-acting Relief valve5 Gauge tap 16 On-off valve6 On-off valve 17 Filter with condensate separator7 Filter with condensate separator 18 Hot water heat exchanger8 Hot water heat exchanger 19 Pressure regulator MONITOR9 Pressure indicator 20 Pressure regulator REGULATOR

10 Pressure regulator MONITOR 21 On-off valve11 Pressure regulator REGULATOR 22 Boiler to heat water


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REGULATION PLANT - INTERRUPTIBLE

p mon pre. > 12 BAR

TYPE C

POS. DESCRIPTION POS. DESCRIPTION1 Enbloc Insulating Joint 9 Pressure indicator2 On-off valve 10 Pressure regulator MONITOR3 On-off valve 11 Pressure regulator REGULATOR4 Blind flange 12 Pressure indicator5 Gauge tap 13 On-off valve6 On-off valve 14 On-off valve full passage7 Filter with condensate separator 15 Direct-acting Relief valve8 Hot water heat exchanger 16 Boiler to heat water


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p mon pre. 12 BAR

TYPE D


1 Enbloc Insulating Joint 8 Pressure indicator2 On-off valve 9 Pressure regulator MONITOR3 On-off valve 10 Pressure regulator REGULATOR4 Blind flange 11 Pressure indicator5 Gauge tap 12 On-off valve6 On-off valve 13 On-off valve full passage7 Filter with condensate separator 14 Direct-acting Relief valve


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ATTACH. 3B MEASUREMENT PLANT WITH FISCAL VALUE

MEASUREMENT PLANT WITH FISCAL VALUE

Qero < 4000

TYPE 10


30 Thermometer pocket 39 Telereading module31 Temperature indicator 40 On-off valve32 Pressure indicator 41 On-off valve33 Gauge tap 42 On-off valve34 On-off valve 43 Blind flange35 Meter 44 On-off valve36 Thermoresistance 45 Enbloc Insulating Joint37 Straingauge pressure transmitter 46 Blind disc38 Type 1 Calculator


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4000 Qero < 30000

TYPE 30

With meters of the same class the elements 46 and 48 are optional.


30 Thermometer pocket 40 Type 2 Calculator31 Temperature indicator 41 Telereading module32 Pressure indicator 42 On-off valve33 Gauge tap 43 On-off valve34 On-off valve 44 Blind flange35 Meter 45 On-off valve36 Meter 46 On-off valve37 Pressure and temperature recorder 47 Enbloc Insulating Joint38 Pressure transmitter 48 Blind disc39 Thermoresistance


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Qero 30000

TYPE 40

The meters are deemed of the same gauge.


30 Thermometer pocket 39 Thermoresistance31 Temperature indicator 40 Type 2 calculator32 Pressure indicator 41 Telereading module33 Gauge tap 42 On-off valve34 On-off valve 43 On-off valve

35 Meter 44 Blind flange36 Meter 45 On-off valve37 Pressure and temperature recorder 46 Enbloc Insulating Joint38 Pressure transmitter 47 Seal on closed valve


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12000 Qero < 30000

TYPE 60


30 Thermometer pocket 40 Blind flange31 Temperature indicator 41 On-off valve32 Pressure indicator 42 Enbloc Insulating Joint33 Gauge tap 43 Low dp transmitter34 On-off valve 44 High dp transmitter35 Diaphragm-holder 45 Pressure transmitter36 On-off valve 46 Thermoresistance37 Multivariable transmitter 47 Type 2 Calculator38 On-off valve 48 Telereading module39 On-off valve 49 Blind disc


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30000 Qero < 60000

TYPE 61


30 Thermometer pocket 42 Enbloc Insulating Joint31 Temperature indicator 43 Low dp transmitter32 Pressure indicator 44 High dp transmitter33 Gauge tap 45 Pressure transmitter34 On-off valve 46 Thermoresistance35 Diaphragm-holder 47 Sampling system36 On-off valve 48 Volumic mass transmitter37 Multivariable transmitter 49 Type 2 Calculator38 On-off valve 50 Electric recorder

39 On-off valve 51 Telereading module40 Blind flange 52 Blind disc41 On-off valve


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Qero 60000

TYPE 62


30 Thermometer pocket 42 Low dp transmitter31 Temperature indicator 43 High dp transmitter32 Pressure indicator 44 Pressure transmitter33 Gauge tap 45 Thermoresistance

34 On-off valve 46 Sampling system35 Diaphragm-holder 47 Volumic mass transmitter36 On-off valve 48 Type 2 calculator37 On-off valve 49 Electric recorder38 On-off valve 50 Telereading module39 Blind flange 51 Blind disk

40 On-off valve 52Supply unit with back-up with

autonomy 24 ore41 Enbloc Insulating Joint


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EQUIPMENT CHARACTERISTIC

The characteristics to be supplied during the plant Approval or Modification phases are the

following:

INSULATING JOINTManufacturerTypeNominal DiameterNominal Pressure

ON-OFF VALVEManufacturerTypeNominal DiameterNominal PressureMaterial

GAUGE TAPNominal DiameterNominal Pressure

THERMOMETER POCKETNominal DiameterNominal Pressure

FILTERManufacturerTypeNominal DiameterNominal PressureFiltering elementCapacitySeal pressure

HEAT EXCHANGERManufacturerTypeNominal DiameterNominal PressureGas capacitySeal pressureThermal capacity

PRESSURE REGULATORManufacturerType

Nominal diameterNominal pressure

Cg valve coefficientCalibration pressure

RELIEF VALVEManufacturerType

Nominal diameterNominal pressureUseful passage sectionK discharge coefficientCalibration pressure

BOILERManufacturerThermal capacity

PRESSURE INDICATORManufacturerType

Scale

TEMPERATURE INDICATORManufacturerType

ScaleMETER

ManufacturerTypeNominal diameterNominal pressureMax flow rate QmaxMin flow rate Qmin

DIAPHRAGM-HOLDERManufacturerTypeNominal diameterNominal pressureInside diameterDesign ruleTap type


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PRESSURE RESISTANCEManufacturerTypeScale

THERMORESISTANCEManufacturerTypeScale

LOW DP TRANSMITTER

ManufacturerTypeScale

HIGH DP TRANSMITTER

ManufacturerTypeScale

VOLUMIC MASS TRANSMITTERManufacturerType

MULTIVARIABLE TRANSMITTERManufacturerType

METERManufacturerTypeHomologation

BLIND FLANGE


BLIND DISC



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ATTACH. 3C REMI PLANT WITH VARIABLE PRESSURE AND TEMPERATURE

REMI PLANT WITH PIPE P AND T

TYPE OF CUSTOMER CHARACTERISTICS FILTERING LINES

NON Public Utility Min. 2 lines - (F) QimpINTER. Not Public Utility Min. 2 lines - (F) 0.5 QimpINTER. 1 line - (F) Qimp

F = SEPARATING FILTER

MEASUREMENT PLANT CHARACTERISTICS

Diagrams of acceptable plant structures and explaining notes areincluded in attach. 2

IN THE FOLLOWING PAGES THE FOLLOWING 3 SCHEMES ARE DESCRIBED:

- SCHEME WITH VOLUMETRIC MEASURE (4000 Qero < 30000 m3/h)

- SCHEME WITH VENTURIMETRIC MEASURE (12000 Qero < 30000 m3/h)

- SCHEME FOR MOTOR TRANSPORT PLANT (300 Qero < 4000 m3/h)


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PIPE P AND T : VOLUMETRIC


1 Enbloc insulating joint 10 Meter

2 On-off valve 11 Pressure transmitter3 Gauge tap 12 Thermoresistance4 On-off valve 13 Type 2 calculator

5Filter with condensateseparator

15 Telereading module

6 Themometer pocket 16 P and T recorder7 Temperature indicator 17 On-off valve8 Pressure indicator 18 Enbloc insulating joint9 On-off valve


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PIPE P and T : VENTURIMETRIC


1 Enbloc insulating joint 11 Multivariable transmitter2 On-off valve 12 Low dp transmitter3 Gauge tap 13 High dp transmitter4 On-off valve 14 Pressure transmitter5 Filter with condensate

separator15 Thermoresistance

6 Thermometer pocket 16 Type 2 Calculator7 Temperature indicator 17 Electric recorder8 Pressure indicator 18 Telereading module9 On-off valve 19 On-off valve

10 Diaphragm-holder 20 Enbloc insulating joint


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ATTACH. 4 - MAXIMUM ALLOWABLE ERRORS IN MEASUREMENT SYSTEMS

Criteria to assure correct measurementThe maximum allowable errors shown in the following table are defined by legal metrologyregulations with two different levels relating to the first check in the plant and to the

periodic check in the field. However, to assure correct measurement the interested partiesshould not limit themselves to comply with the maximum allowable error, but should strive fora better result adopting the following criteria.During the periodic check, calibration operations should be carried out to bring the total error,or the error of the single equipment, as close to zero as possible, even if the observed error doesnot exceed the maximum value. For Type 2 equipment this action should be takenindependently from the periodic check due date if the check indicates a total error [Ccalculation] or [Q calculation] greater than or equal to 0,8%. However the interested party mayagree stricter limits to increase the equipment accuracy.

Table of the maximum allowable errors in the metric checks

PRIMARY INSTRUMENTS BACK-UP

Pos.Type ofcheck

Measurementsystem

BarPressure

TemperatureC

Deltapimbar

Ccalculat

ion

Qcalculati

on

1 First Volumetric Type 1 0,6%2 Periodic Volumetric Type 1 1,2%3 First Volumetric Type 2 0,3% 0,4 0,6%4 Periodic Volumetric Type 2 0,5% 0,6 1,2%

5 FirstVenturimetric Type

2

0,3% 0,4 0,3% 0,6%

6 PeriodicVenturimetric Type

2 0,5% 0,6 0,4% 1,2%

Note: C calculation = calculation of the total conversion coefficient (includes variables P, T, Z)

Q calculation = calculation of the instantaneous flow rate in m3/h (includes variables P, P, T, Z)All % values refers to the measured value except the P value which refers to the calibration end of scale.

Allowable errors for measurement devices (Back-up and Control)

Table of the maximum allowed errorsMaximum error in the condition of:

Pos. Device Calibration Operation Note

1

Mechanic recorder- pressure- temperature- flow rate dp

0,5%0,5%0,5%

1%1%1%

% referred to e.s.

2Multivariable TransmitterP T deltapi

0,2% 0,5%

3 Electric recorder 0,3% 0,5%

4 Densimeter 0,2% 0,5%0,5% limit referredto analysiscalculation


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ATTACH. 5 - DIAPHRAGM CALIBRATION CERTIFICATE

CERTIFICATE n _____________________________

DATE _____________________________

RIF. _____________ PAGE __________ of ________

Check and gauging according to UNI EN ISO 5167-1 rule: diaphragm n ____________________________________

REQUESTED BY ________________________________________________________________

ADDRESSEE __________________________________________________________

PLANT LOCATION ________________________________________________________________

MEASURED VALUES LIMIT CONDITIONS

d1 ................ mm d max. = 1,0005 d = ................ mm

d2 ................ mm d min. = 0,9995 d = ................ mm

d3 ................ mm 0,2 D d 0,75 D

d4 ................ mm

-------------------------------------------- d 12,5 mm

Average value d ................mm

0,005 D < e < 0,020 D

-------------------------------------------- e max e min. 0,001 D

e ................ mm E max E min. 0,001 D

E ................ mm e E < 0,05 D

F .............. 30 F 60

No bur or other elements visible at first sight at the Entry and Exit edges.The upstream sharp edge complies with the regulations.

The checks have been performed at the temperature of .................. C for the following equipment:

_______________________________________________________________________________________________

WRITTEN BY VERIFIED BY APPROVED BY

__________________________ __________________________ __________________________


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ATTACH. 6 - GAUGING OF THE MEASUREMENT SECTION

IDENTIFICATION DATA

Manufacturer Fabrication year DN Pipe Number

Installed on REMI plant Manufacturer Location

D measured values in mm (to 2 decimal places)D in mm.

Value averageSez. a, b, c

D1 D2 D3 D4

Sez. a

Sez. b

Sez. c

Dmax = 1,003 D = Dmin = 0,997 D =

Sez. d

D measured inmm

Sez. e Dmax= 1,03 D= Dmin= 0,97 D=

Check date At the temperature of C.

Measurement device used

NOTE:

WRITTEN BY VERIFIED BY APPROVED BY

__________________________ __________________________ __________________________


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ATTACH. 7 - REMI PLANT WITH UPSTREAM P MAX 5 BAR

EXPLANATORY NOTES

a) ForewordThe design and implementation of REMI plants should comply with D.M. 24November 1984 "Fire prevention Dispositions for the transportation, distribution,storage and utilization of natural gas with density lower than 0,8", published in thesupplement of the Gazzetta ufficiale n 12 - 15 January 1985.Also the provisions contained in the UNI-CIG 8827 Rule should apply in particular asfar as final reduction plants are concerned.Final reduction plants are defined as those reducing pressure for pipeline gas,

operating with relative entry pressure in the range 0,04 < P max es. 5 bar and exitpressue not higher than 0,04 bar used to supply a distribution network or householdsdirectly.

b) Sizing and number of regulation linesThe design of the regulation lines should be based on the flow rate of the regulationline (Qlin).This flow rate is defined in the following table, on the basis of the n of lines and theplant flow rate (Qimp = maximum flow rate to size the plant, given the forecasts).

PLANTS N.LINES PARAMETERS TO DEFINE Qlin VALUES

CLEARLY INTERRUPTIBLE 1 LINE: Qlin = Qimp

NOT INTERRUPTIBLEsupplying Public Utilitycustomers

2 MAIN LINE. : Qlin = Qimp

3

CHOICE BETWEEN:a FOR EACH LINE: Qlin 0,5 Qimpb - 3 LINES: Qtot 1,5 Qimp

with always 2 linesable to supply

Q 2/3 Qimp.> 3 CASE BY CASE VALUATION

NOT INTERRUPTIBLEsupplying customers not PublicUtility

2 LINE : Qlin Qimp/2

3 CASE BY CASE VALUATION

c) In the case of filters, separation of liquid particles is not mandatory. In this case, ifnecessary, the control operations should be intensified.The minimum filtering capacity of the whole functioning range should be equal to

100% of the solid particles 50 micron and not higher than that defined by themanufacturers for the regular running of specific equipment (e.g. meters, regulators,etc.).

d) As a partial modification to the specification contained in the Procedure Main criteriato size REMI Plants" the valve installed downstream of the pressure regulator can alsobe a butterfly valve.


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e) Thermometers should only be used where good technical standards allow this.f) The meter should be installed in accordance with the manufacturers instruction and

with the rectilinear upstream and downstream distance indicated in the Procedure tosize Remi plants".

g) The equipment should be installed in housings allowed by the D.M. and by the UNI-CIG rules described above.If metallic boxes are used, they should be equipped with appropriate grounding.

h) The schemes mentioned at point 2 refers to minimum REMI plant configurations withthe following characteristics:

P mon max 5 bar not final reduction plant Qimp < 300 m3/h Fiscal measurement in accordance with attach. 2 Automated system.In particular, the FA scheme refers to the minimum configuration for interruptibleaccessory measurement plant. This type of plant may be required for fiscal, contractual,accuracy reasons or for any other reason; it will be usually shunted downstream of themain pressure regulation.For cases other than those described, the following points should be taken into account.

h1) For REMI plants with P mon max > 5 attach. 7 is not applicable.h2) In the case of a final reduction plant, Qero > 120 m3/h and P mon max between

1,5 and 5 bar, it is necessary that, both on the main line and on the possible

emergency line, a second emergency device be installed; in this case one of theemergency devices should be made up of a stop valve to be installed upstream ofthe monitor or incorporated in it.

h3) For every reduction plant (final and not final) if Qero 120 m3/h and P mon max 1,5 bar, the installation of only one emergency device is allowable made up of adouble pressure reduction-regulation overfall incorporated in the reducer,provided it is in accordance with the above UNI-CIG rule.

h4) For plants with Qimp 300 m3/h the measuring plants should also comply, inrelation to the piping, with attach. 2 and 3b.

h5) If the ancillary measurement plant is not interruptible, it must comply with theother schemes shown in the following table, where relevant (e.g. filters orregulators may not be relevant).


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REGULATION PLANT NOT INTERRUPTIBLE

TYPE NF


1 Enbloc insulating joint 12 Meter2 On-off valve 13 Straingauge pressure transmitter3 Gauge tap 14 Thermoresistance4 On-off valve 15 Type 1 calculator5 Filter 16 Telereading module6 Pressure regulator MONITOR 17 On-off valve full passagge7 Pressure regulator REGULATOR 18 Direct-acting Relief valve8 On-off valve 19 Enbloc insulating joint9 Thermometer pocket 20 On-off valve10 Temperature indicator 21 On-off valve11 Pressure indicator


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TYPE F


1 Enbloc insulating joint 11 Meter2 On-off valve 12 Straingauge pressure transmitter3 G

Documents

Sizing Remi Plant