Repair, rehabilitation and renewal of networks

Beside the growth of the cities have gone appearing distinct materials and services that have gone incorporating to the entramado of urban networks composed by pipes of different typologies, material and characteristic.

Attending to the data indicated in the Table 1 extracted of the survey 2010 published by AEAS, can see the heterogeneity of materials that compose the networks of water supply: fibrocemento, ductile smelting, grey smelting, concrete, polyethylene, PVC-Or, PVC-Or, PRFV… Material with very distinct behaviour: flexible, rigid, semirrígidos and in definite with different characteristic.

A data to stand out is the high percentage of pipes of fibrocemento (27,4%) that still today are presents in our networks of distribution, as well as pipes of lead (4%) in tackled domiciliary. At present forbidden the installation of these two materials for the driving of drinkable water.

The networks of driving of water transport a very necessary, scarce and therefore very valuable that it is necessary to protect. The driving of water has to be efficient and sustainable and therefore, the maintenance and repair of the networks has to understand from an economic and environingingmental optics.

Understanding that the networks of pipes have to offer a long life in service, is easy to imagine that during all this useful life present crowd of conditions. The time of necessary for his repair has to be the possible minor to avoid greater losses of water, long time without service, complaints of the users, conditions in the traffic…

In the management of the networks does therefore necessary that establish plans of maintenance (preventive and correctivo) that go countering the deterioration produced by the use in the time. The implementation of plans of maintenance has to collect all those usual operations, and therefore programmed and periodic with seen to retardar or correct the deterioration of the networks.

2.1 preventive Maintenance

This maintenance refers to the actions of inspection and follow-up of the elements of the networks to treat to avoid that it produce his failure. The preventive maintenance is programmed. The time that the element is not into use is the devoted exclusively to the properly said operation. For this reason, the time of preventive maintenance is always inferior to the time of maintenance correctivo.

2.2 Maintenance correctivo

This is a maintenance of repair that realizar after a failure or break in the system, is not programmed previously and is required by a determinate failure (for example, apparition of an escape of water).

The maintenance correctivo includes five periods of time (in which the element of failure is not operative):

• Time passed since it produces the failure until it detects , or time of answer
• necessary Time to have the one who effects the repair (availability of the technical personnel attendant of the repair)
• Time that passes until having of the necessary spare parts to repair the failure.
• Necessary time to amend the failure
• necessary Time for the new put in service of the network (cleaning, disinfection...).

Some of the main reasons of the causes that originate the escapes in the systems of distribution of water are: a wrong election of the materials of the network, a deficient installation and settlement of the pipes, corrosion, deficiencies in valvulería, overpressesures, external performances... These possible origins of the escapes, have to take into account in the handle operational of the network, and in his preventive maintenance, with the end to prolong his useful life without failures.

In this section indicate of general form the tasks directed to repair the small escapes or failures that go appearing during the useful life of the same. In all the cases, will be always necessary a fast performance: identification of the failure, election of the procedure of repair and his execution.

The type of repair to realizar on the pipe will depend of the damage that have produced on the same, and will depend also of the material and type of pipe.

In general, the criteria of selection in a repair are:

• Type of break (net, bite, fissure, reventón)
• Material of the pipe
• external Diameter of the tube
• Element of repair (abrazadera, manguito, manguito autoblocante, virola…).

3.1 Repair without cut of pipe

In case of small breaks or holes that do not require the replacement of the pipe, can realizar fast and durable repairs using abrazaderas of repair, manguitos parties or flexible attachments.

In these cases, in which the damage ocasionado in the pipe is small (for example, a picotazo of a compressesor or machine, a hole or a small fissure), this can repair with a piece of appropriate mechanical repair for the dimension of the failure and the nominal pressesure of the installed pipe. Since it does not realizar the cut of the tube, the piece has to be game or has to allow his desmontaje with the end that it can be joined up to the pipe. The abrazaderas of repair are provistas of an inner board that guarantees an estanqueidad total when realizar the tighten of the screws. The outside is manufactured generally in stainless steel or smelting with painting of protection to avoid problems of corrosion.

These systems of repair are relatively fast since after destapar the pipe can install the piece of repair closing the service in brief and even in occasions without having to realizar a total closing of the supply. With this avoids the cut and casting of the pipe achieving time of restablecimiento of the very reduced service.

In these cases it is necessary to have certainty that the fissure or hole does not go to extend longitudinalmente along the tube. If it thought that this can occur will have to cut the tube deleting the part affected, realizar a repair with cut of pipe.

3.2 Repair with cut of pipe

If the failure produced is of an important dimension, the repair of this will realizar by means of the replacement of the stretch of pipe affected. seccionará The piece of canalisation damaged and will substitute by a new piece of tube (cylinder or carrete) of the same material preferably. In function of the length affected and according to the possibilities of manoeuvrability, will proceed to the union of the new stretch of pipe with the existent canalisation using distinct types of available attachments in the market. In this case it is not necessary that they are split since when cutting the pipe can be entered well in the cylinder or in the existent pipe.

Although the recommended is to repair using pipe of the same material and calibrate, exist also attachments of big tolerance that allow to realizar the repair using a tube of calibrate distinct to the existent. These elements are usually used in the repair of pipes of fibrocemento and grey smelting and his replacement by pipes of plastic materials.

With the rehabilitation of pipes pretends restore the hydraulics capacity of a pipe that has been affected negatively by inner corrosion, increase of the rugosidad, decrease of diameter, leaks… extending like this his useful life. If it did not correct this situation, would arrive to produce greater leaks and failures that can carry to the suspension of the service and costly repairs.

Exist distinct systems of rehabilitation. The traditional method requires the opening of resolves it and of the intervention of poceros skilled. The current technologies of rehabilitation of pipes allow to have of skilled machinery and of material (mainly plastic) for recubrir the internal walls of the pipes affected, solving the problems of leaks and losses of fluids, without need to realizar civil work and reducing therefore the costs of the intervention.

These systems of rehabilitation of pipes without opening of resolve, every time use with greater frequency since they attain to avoid uncomfortable works (cuttings of streets and steeled), the danger of resolve opened, reduce notably the costs and the environingingmental impact.

Is important also signal that the service of the line generally keeps while they execute the works and only realizar the necessary interruptions to install the by-passes corresponding to the stretch where execute the works. Of this way the annoyances for the users are minimum.

Generally the works of rehabilitation without resolves will consist firstly in the detection of the zone to rehabilitate, later in the cleaning of the interior of the stretch and in the installation of the revestimiento inner by any one of the existent methods.

In the cases in which the network was seriously damaged, is recommended the renewal of the network to avoid the innumerable failures and breaks produced, the costs derived of his repair and the annoyances for the neighbours of the zones affected. Besides, in a lot of cases, the antiquity of the networks does advisable also his renewal and replacement.

According to the last data published by AEAS, in 2010 more than 35% of the networks of supply in Spain have an upper antiquity to 30 years. If we look the composition of said networks find that the pipes of fibrocemento represent more than 27% and that 4% of the tackled keep on being of pipes of Lead, material whose installation is not allowed at present.

To this it is necessary to add that in 2010 the no registered water (losses) represents 23,3% of the water supplied. All this, carries to the need of renewal of the networks of supply, but according to data of 2010 only 67% roughly of the municipalities has of a plan of renewal of these networks, by what according to the data of the survey AEAS only renewed 1,3% of said network in 2010.

If we fix us now in the data of the networks of sewerage, observe that more than 42% of the networks has an upper antiquity to the 30 years, but in this case, only 27% of the municipalities has of plans of renewal of his networks of sewerage.

The losses of water in the networks cause high costs, well by direct costs of “production” of water (for example, potabilización, transport, distribution...), well by environingingmental costs (pollution, shortage of resources, problems of health...). This situation aggravates with the growth of the demand and the climatic change.

Next indicate some data presented by the INE (national institute of statistics) in his Survey on the Supply and Saneamiento of the Water (year 2010):

Table 2. Data INE, polls 2010.

Doing an easy calculation obtain that the cost of the losses of water in the networks of supply reached surpassed the billion of euros in 2010. Understanding that every year they present roughly these values of losses of water, are saying that annually they lose some billion of euros in our networks of water supply and that are not acting in the measure that would require treating of a so high cost and of a well so lovely, scarce and necessary.

Remains therefore evident and clear that the not investing in the renewal of the networks turns into a no sustainable cost neither to long neither in the short term.

An integral analysis of costs, instead of one traditional, can change radically the election of the materials of the pipes. The advantages of the plastic materials reveal clearly when considering no only the cost of material but also the costs of transport, installation, maintenance of the network and the environingingmental costs. Besides, it is necessary to take into account the possibilities that offer the plastic materials when making possible technicians of renewal without opening of resolves that they suppose an innovative opportunity and that contributes big economic advantages, social and environingingmental.

It is necessary to take into account that each procedure of repair, rehabilitation or renewal will require of a correct execution of the solution adopted. Many of the problems that find in the networks come derived of a deficient installation (board displaced, occlusion of sand, gravel, in unions with elastic board, wrong execution of the process of union, defective compactación of the terrain or election of the material of coating...).

By all this, is important that the personnel commissioned of the installation of the network like the attendant of his maintenance, repair, rehabilitation or renewal, have the best knowledge on the correct handle and installation of pipes. Demand that the installers of plastic pipes are headlines of the Carné of Specialist in Installation of Systems of plastic Pipes, that issues Asetub, supposes a guarantee that the installation realizar properly.

Appears 3. Obverse and reverso of the Carné of Installer of plastic Pipes.

Carné Of Specialist in Installation of Systems of plastic Pipes

In this initiative of the Spanish Association of manufacturers of tubes and plastic accessories (Asetub) collaborate distinct entities engaged also with the quality, companies of water and entities formadoras that are those that give this skilled course and of high practical content. At present the courses give in 7 centres thanks to agreements of collaboration with the following entities:

• Seville: Emasesa
• Córdoba: Waters of Córdoba, Emproacsa
• Madrid: Cefoim
• Gijón: EMA
• Valencia: Waters of Valencia - Aimplas
• Biscay: Afonvi
• Barcelona: Agbar – Applus.

At present are more than 1.300 the installers that have gone through the specific courses of learning and are headlines of this carné professional. The aim of the course is the improvement of the qualification of the professionals of the sector in the correct handle and installation of the distinct systems of pipes of PVC-Or, PVC-Or, PE, PP and PRFV in the networks of supply, irrigation and saneamiento.

The didactic program is very complete and covers 4 big areas of knowledge.

Introduction: general characteristics of the plastic materials, functional advantages, basic knowledges of hydraulics and interpretation of planes. Rule and certification of quality and legislation.

Products: norm of application, range of diameters and pressesures, range of accessories and procedures of union detailing step by step his correct execution. Other elements of the networks: valves, pozos and caskets of inspection…

Installation: transport, reception, gather. Typology of resolve, bed of support, entibaciones, installation, anchorages, punteos, compactación of the terrain, filling of resolves. Essays to the network (pressesure and estanqueidad). Solution of problems and repairs.

Professional commitment: labour hygiene, measures of prevention and respect to the environingingment.

To obtain more information on installers accredited, courses and announcements can visit our web page (www.asetub.es).

References

• Polls on the Supply and Saneamiento of the Water. Year 2010. INE (5 July 2012)
• Maintenance of networks of water to pressesure. It splits I: Repairs. AEAS (January 2009)
• Manual of installation of plastic pipes. Supply, irrigation and saneamiento. AseTUB (September 2012)
• Improvement of the performance in networks of aqueduct. And. Cabrera. Technological institute of the Water of the UPV (2000)
• drinkable Water supply and saneamiento in Spain 2010. XII national Survey. AEAS (May 2012)
• The benefits of pipeline innovation. The advantages of using plastics for water industries in Italy. To. Marangoni. Althesys (2009).