FR3050856A1 - METHOD AND DEVICE FOR SELECTING A TYPE OF PIPE FOR PRODUCING A FLUID DISTRIBUTION NETWORK - Google Patents

Abstract

This method of selecting a type of pipe for the realization of a fluid distribution network comprises the steps of: a) creating (100) a technical and economic database for at least two types of pipes selected; b) enter (102) into a calculator the characteristic data of the project common to all types of pipes and the data specific to each type of pipe; c) calculating (104), for each type of pipe selected, at least one evaluation function (CF, CE) over a predetermined operating period; d) choose (306) the type of pipe based on the compared results of the evaluation functions for the different pipe types.

Description

Method and device for selecting a type of pipe for producing a fluid distribution network

The present invention relates to a method of selecting a type of pipe for the realization of a distribution network of a fluid.

Fluid distribution networks, especially drinking water distribution networks, are complex installations with a long life, of the order of a hundred years.

During its lifetime, the facility generates significant operating costs. For example, water leaks can occur, greatly increasing the cost of distribution, if they are not repaired and / or causing significant repair costs.

When building a water distribution network, the work undertaken, as well as the equipment used, are very important and very expensive.

In particular, the choice of the type of pipe used to build the distribution network is particularly decisive for the cost of building and operating the network.

Numerous parameters are taken into consideration when choosing this type of pipe, and in particular the initial price of the pipes, as well as the foreseeable lifetime of these pipes.

Taking these parameters into account makes it possible to define the type of pipe used and to construct the installation, then to use it from the pipes of the selected type.

The commonly used selection and exploitation process is relatively basic and largely based on a subjective appreciation of the different types of pipes in a given situation. The object of the invention is to propose a method for selecting a type of pipe for an installation and a method for producing this installation, which allow a more relevant choice of the type of pipe making it possible to reduce over the entire life cycle of the installation the overall economic cost and / or environmental impacts due to this installation. To this end, the subject of the invention is a method of selecting a type of pipe for the realization of a fluid distribution network, comprising the steps of: a) creating a technical and economic data base for at least two types of pipe retained; b) enter into a calculator the characteristic data of the project common to all types of pipes and the data specific to each type of pipe; c) calculating, for each type of pipe selected, at least one evaluation function over a predetermined operating period; d) choose the type of pipe based on the compared results of the evaluation functions for the different pipe types.

According to particular modes of implementation, the selection method comprises one or more of the following characteristics: at least one evaluation function comprises: the acquisition cost of the pipes; the cost of operating the network over a predetermined period of time. - the acquisition cost includes one or more of the costs included in the group consisting of: - the financial cost of purchasing the pipes; - the financial cost of financing; - the financial grant product; - the financial cost of installation. - the operating cost includes one or more of the costs included in the group consisting of: - the financial cost of pumping; - the financial cost of repair; - the financial cost of maintenance; - the financial cost of fluid losses due to leaks. said at least one evaluation function includes the cost of recycling the pipes; - the cost of recycling includes one or more of the costs included in the group consisting of: - the financial cost of dismantling; - the financial product resulting from recycling. - the acquisition cost includes one or more of the costs included in the group consisting of: - the environmental cost of raw materials; - the environmental cost of pipe making; - the environmental cost of transporting the pipes; - the environmental cost of laying pipes. - the cost of operation includes one or more of the costs included in the group consisting of: - the environmental cost of pumping; - the environmental cost of cathodic protection; - the environmental cost of repair; - the environmental cost of fluid losses due to leaks. the financial cost of fluid losses due to leaks and the environmental cost of fluid losses due to leakage is calculated from the quantity of fluid lost for 1 m3 of fluid for year N, this quantity of lost fluid wln being calculated as follows: where:

rh {ats is the projected index of annual water loss WLfinai are the water losses at the end of the service life in m3 / year Final is the estimated service life, expressed in years Λ / is the age of the pipeline and:

Where: L is the length of the network, in km LLipina_i is the linear water loss index at the end of the estimated service life. - the cost of recycling includes one or more of the costs included in the group consisting of: - the environmental cost of dismantling; - the environmental cost of treatment; - the environmental product of recycling. the types of pipes comprise at least two types included in the group consisting of: ductile iron pipes; - welded steel pipes; - polyethylene pipes; - polyvinyl chloride pipes; - bi-oriented polyvinyl chloride pipes; - plastic pipes reinforced with glass fibers. - said predetermined operating time is between 75 and 125 years. - the characteristic data of the project include one or more of the data included in the group consisting of: - the geographical location of the network; - the place of installation; - the length of the network; - the service pressure of the network; - the type of distribution; and - the nominal diameter of the pipes. said method for installing a fluid distribution network comprises: a) a phase for selecting a type of pipe according to the aforementioned type for producing the network; b) a pipe laying phase of the type selected to achieve the distribution network. The subject of the invention is also a method of installing a distribution network, as well as a device for selecting a type of pipe comprising specific computer means for implementing the method of the aforementioned type. The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the drawings, in which: FIG. 1 is a schematic view of a distribution network of FIG. water; FIG. 2 is a device for implementing the selection method according to the invention;

Fig. 3 is a flowchart of the selection method; and FIGS. 4 and 5 are diagrammatic representations of the data taken into account during the different phases of the life cycle of the fluid distribution network between the data taken into account from a financial and environmental point of view.

In Figure 1 is shown an installation 10 for distribution of drinking water from a river 12 to homes 14 or industrial buildings 16.

As known per se, the installation comprises a water treatment station 20 connected to the river through pumps 22. The installation comprises a network 24 connected to its inlet, at the outlet of the treatment station through main pumping means 26.

The network 24 has branches 28 serving each of the homes 14 and industrial buildings 16. Intermediate pumping facilities 30 are disposed on the network 24. As known per se, the network consists of a set of pipes 32 connected end to end. to form pipes. These pipes are according to the choice made for the installation in steel, cast iron, plastic or any other suitable material. For certain types of materials used, in particular steel, cathodic protection is ensured by permanent circulation of an electric current in the network. For this purpose, a suitable feed installation is set up.

In certain circumstances, the network 24 has a leak 34 at the origin of a loss of water and thus additional cost in the distribution of water. This leakage ultimately requires an expensive intervention for the repair, and in particular the possible replacement of the defective pipes.

The device 50 for selecting a type of pipe for the realization of the distribution network 24 comprises a computer 52, such as a personal computer with software 54 stored in a memory. The software 54 is able to implement the selection method according to the invention, as defined in particular with respect to FIG.

In addition, the installation includes a database 56 comprising network definition information.

This information is listed in the following table:

Three types of distribution can be considered: - Gravity system: no pumping necessary; - Artificial gravity system (for example, with a water tower): no pumping necessary, since the pipes evaluated are located in the gravitational part of the network; - Pumping system: pumping necessary to face the elevation gradient and ensure flow and pressure.

This information is filled in by the user during each project from a suitable interface of the software 54, according to the characteristic information of the network to be produced.

A base 58 includes general financial information characteristic of the context, in which the network will be installed and operated.

This general financial information is presented in the following table:

A third base 60 includes information on different types of hoses that can be used.

This information characterizes the pipe itself. They are defined in the following table:

A base 62 gathers information specific to the transport of pipes from the production plant of the laying site.

This information is shown in the table below.

A base 64 includes information on the installation of these pipes in the installation.

It includes the information in the table below.

A base 66 gathers information on the operation of the installation.

This information is grouped in the table below.

Finally, a base 68 gathers information on the end of life of the installation. This information is shown in the table below.

The software 54 is able to provide interfaces adapted for the user to enter the information contained in each of the bases 56 to 68. Some of this information is permanently stored and can not be modified by the user.

The software 54 is able to implement the algorithm illustrated in FIG. 3. At step 100, the user is invited to define the characteristics of several types of pipes that can be used in the project. This information is provided for each of the types of pipes used mainly in bases 60 to 68.

When the method is implemented several times, the information provided is stored and used from one time to the other. In step 102, the software 54 prompts the user to fill in the information defining the project, that is to say the characteristic information of the network to be realized, as well as the conditions of use of this network. This information is stored mainly in the bases 56 and 58. This information includes the network operating time. This duration is advantageously taken between 75 and 125 years.

For each type of pipe, among the n types defined in step 100, a calculation of several evaluation functions is carried out in step 104 by the software 54. In the example considered, two evaluation functions are defined .

A first CF rated financial evaluation function determines the overall costs and financial gains resulting from the network lifecycle. This life cycle and the parameters that characterize it are detailed in Figure 4.

A second CE rated environmental assessment function is also calculated. It takes into account the phases of the life cycle detailed in Figure 5.

Whatever the evaluation function (financial or environmental), the evaluation function covers three successive phases of the product life cycle, namely the acquisition A of the pipes designated by the reference 200 in FIGS. 4 and 5, the operation E of the network designated by the reference 202 and the recycling R of the pipes of the network designated by the reference 204.

Thus, for each phase of the life cycle 200, 202, 204, a financial cost CFA, CFE, CFR respectively and an environmental cost CEA, CEE, CER respectively are determined.

Each evaluation function comprises at least an acquisition cost 200 and an operating cost 202. Advantageously, it comprises a recycling cost 204.

The financial evaluation function CF will now be described.

The financial evaluation function is the sum of a financial acquisition cost CFA, a financial operating cost CFE and a financial cost of recycling CFR, corresponding to the respective phases 200, 202 and 204 illustrated on the figure 4.

Thus, CF = CFA + CFE + CFR.

The financial cost of the CFA acquisition is provided by the sum of the purchase cost of the CFA1 pipes, the cost of financing the CFA2 pipes, the cost, and more precisely the gain of the subsidies that can be obtained CFA3 and the CFA4 installation cost. This CFA4 installation cost is broken down into a CFA41 excavation and backfilling cost, a CFA42 assembly cost, a CFA43 assembly control cost, a CFA44 junction area liner repair cost, a cost CFA45 junction area cladding repair, installation cost of CFA46 supplemental protection and potential additional cost CFA47.

Thus, CFA = CFA1 + CFA2 + CFA3 + CFA4 with CFA4 = CFA41 + CFA42 + CFA43 + CFA44 + CFA45 + CFA46 + CFA47.

The method of calculating these different costs is detailed in the following table:

The CFE operating financial costs, corresponding to phase 202, are the sum of a CFE1 pumping cost, a cost resulting from CFE2 failures, a CFE3 cathodic protection cost, and a cost resulting from fluid losses due to CFE4 leaks. The cathodic protection cost is broken down into a CFE31 annual electricity consumption cost and a CFE32 non-electrical cost.

Thus, CFE = CFE1 + CFE2 + CFE3 + CFE4 with CFE3 = CFE31 + CFE32.

The method of calculating these different costs is detailed in the table below.

In order to take into account fluid losses due to leaks, the quantity of water lost is determined according to the following model.

Water leaks are one of the major cost items and a major contributor to the environmental footprint of pipeline systems. However, very few models for calculating water leaks exist today. This parameter is highly variable and depends on the material of the pipeline, the installation process, the age and the length of the network, among other factors.

The formula for the amount of water lost per m3 of water for the year N has been established in the following manner and experience shows that it is a satisfactory estimate.

Traditionally, water leaks for a given year (N) are calculated using the following formula:

Where τίβαΚΝ is the "leakage rate" for a given year, and is calculated as follows:

Where: • Qi "is the flow at the inlet of the network (in m3 / s) • Qo-m is the flow at the outlet of the network (in m3 / s)

It is generally accepted that τ1βαΜ, increases with time, the rate of increase of leakage in percentages can thus be determined (rlsek) and the following formula can be established:

We can therefore assume that water leaks increase exponentially each year depending on the rate of increase in leakage. The following equation is based on this assumption:

(1) Where a and b are unknown constants. rleak may vary depending on the types of materials used to construct the water pipe system. An average value of 0.5% is advantageously used for all pipe materials.

It is generally accepted that water leaks are non-existent for at least the first year of service of the water pipe system, therefore:

It is also established that network operators know, or can estimate, the linear loss index of the network at the end of its life. A high leakage rate is indeed a decision criterion for the renewal of the pipeline. Therefore, by asking the grid operator, the net leakage index of the network at the end of its life, WLFiruü can be determined.

Using these data, equation (1) can be solved and the following formula is obtained:

Finally, the financial cost of recycling CFR corresponding to the phase 204 of Figure 4 is formed by the sum of the financial cost of dismantling CFR1 and the cost, usually consisting of a gain, CFR2 recycling of the material constituting the pipes.

Thus, CFR = CFR1 + CFR2.

The financial costs of recycling are detailed in the following table.

For each of the costs, in which time occurs, a discount rate is applied according to the rule defined below.

All future costs are calculated based on current estimates of these costs, applying a discount rate to reflect their present value. The discounted cost is calculated as follows:

where: l0 is the investment in the year 0 D, is the cost in the year t

Rt is the income in the year t a is the discount rate H is the year of the network's end of operation.

The discount rate is provided by the user.

The CE environmental assessment function will now be described.

The environmental assessment function is the sum of an environmental cost of CEA acquisition, an EEC environmental cost of operation and an environmental CER recycling cost, corresponding to the respective phases 200, 202 and 204 illustrated in figure 5. Thus, CE = CEA + CEE + CER. Life cycle assessment (LCA) is an internationally recognized method that assesses the potential environmental impacts of products or services throughout their life cycle, from the extraction of raw materials, taking into account the transportation, production, use and end-of-life treatment. Lifecycle analysis identifies the relative contribution of different phases of the life cycle, providing opportunities to improve the environmental performance of products, inform decision-making, and support marketing efforts and communication.

The impacts described by the LCA are estimates of relative and potential impacts, not direct measures of actual impacts. The Life Cycle Inventory (LCI) compiles all the flows of materials used, energy consumed, waste, water, and emissions generated by each stage of the life cycle.

Advantageously, all the secondary lifecycle inventory data used to calculate the EC environmental assessment function of the software 54 come from the ecoinventv2.2 database (Frischknecht et al., 2007).

Most of the data in the ecoinvent database are of European origin and these data therefore reflect the conditions and processes of the European industry.

The indicators assessed by the EC environmental assessment function are: Carbon footprint (expressed in kg C02-eq) The carbon footprint indicator is based on the IPCC methodology (Barker, 2007, an assessment of the Intergovernmental Pane on Climate Change ). It measures the potential impact on climate change generated by a product, process, or organization. It takes into account the ability of a greenhouse gas to influence radiative forcing, expressed by a reference substance at a specified time horizon. The median characterization factors are expressed in kg C02-equivalent and cover a period of 100 years. The depletion of abiotic resources (fossils), corresponding to the quantity of fossil energy resources consumed (oil, natural gas, coal, etc.) and expressed in MJ.

This indicator, based on the methodologies developed by Guinea et al. (2001 -Life cycle assessment: an operational guide to the ISO standards) measures the potential impact of the product on the depletion of fossil resources. It takes into account the lower calorific value of the different resources.

The term fossil resources refers to a set of resources containing hydrocarbons. Characterization factors are based on the energy content of the resource. The water withdrawn, corresponding to the total quantity of fresh water taken from rivers and aquifers (expressed in m3).

This indicator measures the total water withdrawal associated with a product, process or organization. It takes into account water (whether evaporated or discharged downstream again) and excludes turbined water (water used for hydropower generation). In addition, the indicator takes into account drinking water, irrigation water, water used in industrial processes (including cooling water).

The data used for each phase of the life cycle are described below.

The environmental cost of CEA acquisition is provided by the sum of the environmental cost of raw material acquisition CEA1, the environmental cost of manufacturing CEA2 pipes, the environmental cost of CEA3 transport and the environmental cost of CEA4 installation.

Thus, CEA = CEA1 + CEA2 + CEA3 + CEA4.

The environmental cost of acquiring CEA1 raw materials is broken down into the cost of acquiring raw materials from CEA11 pipes, an environmental cost of acquiring CEA12 interior and exterior coatings, and an environmental cost of acquiring raw materials from joints. and the manufacture of CEA13 seals.

Thus CEA1 = CEA11 + CEA12 + CEA13.

The method of calculating these different costs is detailed in the following table.

The environmental cost of raw material acquisition CEA11 pipes takes into account the environmental impacts of extraction and production of the raw materials needed for each pipeline solution.

The following table shows the sources of the data used for this step. Data on the raw materials of pipelines

The environmental cost of acquiring CEA12 interior and exterior cladding takes into account the environmental impacts of extracting and producing the raw materials needed for the production of interior and exterior liners.

The following two tables show the sources of the data used for each pipe solution for the exterior and interior cladding, respectively.

Pipe coating solutions

2Alloy Zinc / Aluminum - 85% / 15%

Pipe lining solutions

The environmental cost of raw material acquisition and manufacture of CEA13 seals takes into account the environmental impacts of the extraction and production of raw materials required for the manufacture of seals. These can be used when assembling ductile iron pipes, welded steel pipes, GRP pipes and bi-oriented PVC pipes.

These seals are made of synthetic rubber (eg EPDM). The ecoinvent database v2.2 refers to it as' synthetic rubber, at plant / RER Due to the lack of data, no rubber processing step is taken into account.

The environmental cost of acquisition for the manufacture of CEA2 pipelines takes into account the environmental impacts of converting raw materials into ready-to-use pipelines.

The following table shows the data used for this step.

Pipeline Manufacturing Data

The environmental cost of acquisition corresponding to the transport of the pipes to the CEA3 installation site takes into account the environmental impacts related to the transport of the pipes from the manufacturing plants to the installation site. The user defines a transport scenario by giving a transport distance and selecting the transport used from the following 4 types of transport: transport by truck, by train, by barge and / or by ship.

The data used for this step are those provided by the ecoinvent v2.2 database.

The environmental cost of acquisition for the CEA4 installation takes into account the environmental impacts of laying pipes.

The laying of the pipes is divided into 4 stages. The environmental cost of acquisition for the installation is therefore the sum of an environmental cost of excavation of the ground to dig trench CEA41, an environmental cost of assembly of the CEA42 pipe, an environmental cost of backfilling CEA43, and, the where appropriate, an environmental cost of pavement reconstruction CEA44.

Thus, CEA4 = CEA41 + CEA42 + CEA43 + CEA44.

The environmental costs of CEA41 soil excavation, CEA43 backfilling and CEA44 pavement reconstruction are calculated from the following data.

The characteristics of the trench are based on EN 1610 standards and presented in the following table.

Characteristics of the trench

* OD = outside diameter of the pipe expressed in mm

Once the volume of excavated soil is calculated, the amount of energy required during excavation and backfilling is obtained using the data presented in the following table for the calculation of CEA41 and CEA43.

Energy requirements for land handling during excavation and backfilling

Four installation conditions are proposed to the user in software 54 for the calculation of CEA43: 1. Type A: backfill imported with compaction 2. Type B: backfill imported without compaction 3. Type C: native backfill with compaction 4. Type D: native backfill without compaction

For the four different types of laying, the excavated and unused soil is sent by truck to a landfill. A transport distance of 20 km is estimated.

For scenarios A and C, where compaction takes place, the following data is used:

Energy requirement for compaction of the earth

The reconstruction of the road depends on the installation environment. Thus: - in rural areas there is no road reconstruction; - in urban areas the road is reconstructed for the entire width of the trenches; - in semi-urban areas, the road is reconstructed for half the width of the trenches.

The calculation of the environmental cost of assembly of CEA42 pipes is thus estimated.

For most of the pipe solutions evaluable in the software 54, the pipes are locked during assembly, with possible jointing. In this case, no additional environmental impact is taken into account.

The welded steel pipes can be assembled on site. In this case, ecoinvent v2.2's 'welding, gas, steel / RER' dataset is used as the basis for software 54 to estimate the environmental impacts of the pipe assembly.

The environmental cost of the EEC operation is provided by the sum of the environmental cost of operation for EEC1 pumping, the environmental cost of EEC2 cathodic protection, the environmental cost of EEC3 repairs and the environmental cost of fluid losses due to EEC4 leakage.

Thus, CEE = CEE1 + CEE2 + CEE3 + CEE4.

The environmental cost of operation for pumping CEE1 takes into account the environmental impacts of the production of electricity consumed for pumping. Electricity generation is modeled according to the electrical mix of the study area, defined as a general parameter.

Pumping is necessary to deal with the elevation gradient between the two ends of the network and the pressure drops.

The pressure losses are the hydraulic energy losses mainly caused by the viscosity of the water and its friction against the walls of the pipes. They result in an increase in energy consumption for pumping.

The daily energy requirements for pumping (in kWh / day) are calculated as follows:

Where: E: daily pump energy (kWh / day) d: daily pump time (h / day) - user defined g: gravitational constant (m / s2), with g = 9.81 Q: flow rate (m3 / s) - user defined EG: elevation gradient (m) - defined by the user j: pressure drop (in m of fluid per m of pipeline) L: length of the network (in m) heff: hydraulic efficiency (defaults to 70%) eeff: electricity efficiency (defaults to 70%)

The pressure drops are calculated using the Darcy and Colebrook-White formulas.

Darcy's formula is the general formula for pressure drop calculations:

Where: j: pressure drop (in m of fluid per m of pipeline) λ: pressure loss coefficient determined using the Colebrook-White ID formula: inside diameter of the pipe (m)

The Colebrook-White formula is used to calculate the pressure drop coefficient:

Or :

Re: Reynolds number (without unit) μ: kinematic viscosity of the fluid at the operating temperature (m2 / s or St) - the fluid considered here is water and the kinematic viscosity is 1.31x102 m2 / sk: roughness3 of equivalent pipe area (m) 3k is not equal to the height of the imperfections of the surface studied; it is a theoretical concept that represents the roughness of surfaces.

In the Colebrook-White formula, the first term of the logarithmic function corresponds to the pressure drops due to the internal friction of the liquid acting on itself. The second term corresponds to the pressure losses caused by the friction of the liquid against the wall of the pipe (k = 0 for an ideally smooth pipe).

Default roughness of pipes, if necessary with internal lining

The environmental cost of operation for CEE2 cathodic protection (where applicable) takes into account the environmental impacts of the generation of electricity consumed for cathodic protection. Only ductile cast iron and welded steel piping may require cathodic protection.

Electricity generation is modeled according to the electrical mix of the study area.

The environmental cost of operation for CEE3 repairs takes into account the environmental impacts of pipe replacement in case of failure.

A failure is assumed to have the same environmental impact as the acquisition and dismantling of the pipeline. Thus, the software 54 estimates that the environmental impact of a replacement of the pipe in case of failure is: - that of a new pipe produced, transported, laid; - plus the impact of the dismantling of an old pipeline and its disposal in landfill or incineration or recycling.

The environmental cost of operation due to fluid losses due to EEC4 leaks takes into account the environmental impacts of the treatment of drinking water lost due to leakage. This stage of the life cycle is modeled from the ecoinvent dataset v2.2 'tap water, at user / RER' for water treatment data, excluding the environmental impacts related to the infrastructures that supply the food. in water.

Finally, the environmental cost of CER recycling corresponding to phase 204 of figure 5 is formed by the sum of the environmental cost of dismantling CER1, the environmental cost of treatment at the end of life of CER2 pipes and the environmental cost, generally consisting of gain, recycling CER3 material.

Thus, CER = CER1 + CER2 + CER3.

The environmental cost of recycling by dismantling CER1 is determined as follows.

The calculation made by software 54 is based on the fact that the pipe is disassembled only if a new pipe must be laid. The impact of removal and dismantling is thus attributed to the new pipe laid.

The environmental cost of recycling by CER2 waste treatment is determined as follows. The user provides the percentage of pipelines that are removed and dismantled at the end of their service life, as well as the percentage of recycled pipelines. Dismantled and non-recycled pipelines, usually made of plastic, are considered to be dumped or incinerated.

Pipes that are not removed and remain underground are considered inert. Thus, no environmental impact is accounted for.

End of life transport is not included in software 54.

The environmental cost of recycling by the potential profit related to end-of-life valuation CER3 takes into account several CER31 and CER32 benefits detailed below.

Thus, CER3 = CER31 + CER32.

The CER31 potential profit for a plastic incinerated pipe with energy recovery takes into account incineration with heat recovery and electricity generation. The heat and electricity recovery calculations are based on the lower heating value values and are calculated as follows: - 20% of the district heating output, which replaces the light fuel heating - 10% of the electrical output, modeled with the electrical mix of the area where the product passes its end of life

Advantageously, the following lower calorific values (ecoinvent v2.2) are used: - PE: 42.47 MJ / kg - PVC and PVC bi-oriented: 21.51 MJ / kg - PRV: 31.7 MJ / kg

The CER32 potential profit related to the recycling of materials is taken into account as indicated below.

Recycling is only considered for ductile iron and welded steel pipe.

For both materials, the environmental impact of recycling is - according to EN 15804 - the balance between the potential impacts associated with the recycling process (ie production from scrap) and the potential benefit (negative impact) coming from because the material produced from scrap would prevent the production of material from ores.

A 100% recycling efficiency (ratio between the amount of waste collected and the amount of recycled material produced) is assumed.

For ductile iron or steel materials containing recycled materials, the potential benefits and impacts are assigned to the pipe being studied.

The distribution of the impacts and benefits of recycling is carried out according to the European standard EN 15804 for the Environmental Declarations of Construction Products, Annex A.

The following formulas are used by software 54 to calculate the net environmental impacts for materials from the point of view of raw materials and from the point of view of material recovery:

r ± \ content of the pipe in recycled material (%) i? 2: quantity of pipeline sent for recycling (%)

Ev. environmental impacts related to production from materials extracted from the natural environment (eg iron ore smelting)

Es \ environmental impacts related to production from recycled materials (eg from scrap)

Er: environmental impacts related to the recycling process (eg scrap processing of part of welded steel pipes at end of life) EVt \ environmental impacts related to avoidance of extraction of raw materials from the natural environment At the end of the calculation of the financial and environmental evaluation functions by the computer, a choice of pipe is made by the computer at step 306. The pipe selected among the various types of pipe evaluated is by for example, the hose with the highest rating in the financial evaluation function and / or the environmental assessment function. In step 308, the installation of the pipes chosen in step 306 is carried out and the network thus constituted is operated for a determined period of time before being recycled.

Claims (15)

1A method of selecting a type of pipe for the realization of a fluid distribution network comprising the steps of: a) creating (100) a technical and economic database for at least two types of pipes selected; b) enter (102) into a calculator the characteristic data of the project common to all types of pipes and the data specific to each type of pipe; c) calculating (104), for each type of pipe selected, at least one evaluation function (CF, CE) over a predetermined operating period; d) choose (306) the type of pipe based on the compared results of the evaluation functions for the different pipe types. 2. - Selection process according to claim 1, characterized in that at least one evaluation function (CF, CE) comprises: - the cost of acquisition of the pipes (CFA; CEA); - the cost of operating the network over a predetermined period of time (CFE, CEE). 3. - Selection process according to claim 2, characterized in that the acquisition cost (CFA) comprises one or more of the costs included in the group consisting of: - the financial cost of acquiring pipes (CFA1); - the financial cost of financing (CFA2); - the financial grant product (CFA3); - the financial cost of laying (CFA4). 4. - A selection method according to any one of claims 2 to 3, characterized in that the operating cost (CFE) comprises one or more of the costs included in the group consisting of: - the financial cost of pumping (CFE1 ); - the financial cost of repair (CFE2); - the financial cost of maintenance (CFE3); - the financial cost of fluid losses due to leaks (CFE4). 5. - Selection process according to claim 2, characterized in that said at least one evaluation function comprises: - the cost of recycling pipes (CFR, CER). 6. - Selection process according to claim 5, characterized in that the recycling cost (CFR) comprises one or more of the costs included in the group consisting of: - the financial cost of dismantling (CFR1); - the financial product resulting from recycling (CFR2). 7. - Selection process according to any one of claims 2 to 6, characterized in that the acquisition cost (CEA) comprises one or more of the costs included in the group consisting of: - the environmental cost of the raw materials ( CEA1); - the environmental cost of pipe manufacturing (CEA2); - the environmental cost of transporting pipes (CEA3); and - the environmental cost of laying pipes (CEA4). 8. - A method of selection according to any one of claims 2 to 7, characterized in that the operating cost (CEE) comprises one or more of the costs included in the group consisting of: - the environmental cost of pumping (CEE1 ); - the environmental cost of cathodic protection (CEE2); - the environmental cost of repair (CEE3); and - the environmental cost of fluid losses due to leakage (CEE4). 9. - A method of selection according to claim 4 or 8, characterized in that the financial cost of losses of fluid due to leakage (CFE4) and the environmental cost of fluid losses due to leakage (CEE4) is calculated from the quantity of fluid wln lost for 1m3 of fluid for year N, this quantity of lost fluid wln being calculated as follows: where: rîeaks is the projected index of annual increase in water losses WLfinai are the water losses at the end of the service life in m3 / year Final is the estimated service life, expressed in years N is the age of the pipeline and: Where: l is the length of the network, in km M / fij ,,; is the linear water loss index at the end of the projected service life. 10. - Selection process according to claim 5 or 6, characterized in that the recycling cost (CER) comprises one or more of the costs included in the group consisting of: - the environmental cost of dismantling (CER1); - the environmental cost of treatment (CER2); and - the environmental product of recycling (CER3). 11. - Selection process according to any one of the preceding claims, characterized in that the types of pipes comprise at least two types included in the group consisting of: - ductile iron pipes; - welded steel pipes; - polyethylene pipes; - polyvinyl chloride pipes; - bi-oriented polyvinyl chloride pipes; and - fiberglass reinforced plastic pipes. 12. - Selection method according to any one of the preceding claims, characterized in that said predetermined operating time is between 75 and 125 years. 13. - Selection method according to any one of the preceding claims, characterized in that the characteristic data of the project comprise one or more of the data included in the group consisting of: - the geographical location of the network; - the place of installation; - the length of the network; - the service pressure of the network; - the type of distribution; and - the nominal diameter of the pipes. 14. - Method for installing a fluid distribution network comprising: a) a phase of selection of a type of pipe according to any one of claims 1 to 13 for the realization of the network; b) a pipe laying phase of the type selected to achieve the distribution network. 15.- Device comprising specific computer means for carrying out the method according to any one of claims 1 to 14.