Decision support when choosing water network materials

When choosing the material to be applied in a water or waste water network, it is certain that several factors arise when weighing the decision. Usually, the investment involved is one of the factors that comes first. But such factor is apparent, who never heard the popular expression “cheap can be expensive”? Also, it is often assumed that when something is good, it is expensive, but when we talk about pipeline materials and designs, these “key expressions” aren’t true.

Opting for an economically advantageous solution may bring higher costs in the future (high failure rate and breakdown, increasing the level of water losses in the network). On the other hand, with the current economic crisis that still affects the sector, there is an increased need to rationalize and legitimize investments, so it may be unjustified to opt for high investment technical solutions.

Even so, nowadays, to rationalize and legitimize investments, replacing an entire pipeline is completely out of question. So, assessing and evaluating the condition of a pipeline is the key to postpone investments and select the pipeline sections to be rehabilitated / replaced.

In a pipe material choosing process, there are two important requirements to note: the longevity and reliability of the material. The asset must have longevity and reliability for the drive to which is intended. Therefore, the managing entity uses the manufacturer’s technical support, the engineering offices and sometimes to the construction company, aiding the information gathering about the best materials to use in your network. In order to guarantee adequate decisions, some variables that influence the choice of materials are placed in the decision scale, such as:

  • Durability and reliability
  • Investment and its sustainability
  • Quality, proven by product certificates and sanitary certificates (if applicable)
  • After-sales technical support
  • Design

In addition to these variables and directly linked to the reliability of the material, there are the most technical aspects:

  • Safety coefficients
  • Hydraulic capacity
  • Permeability and ion migration
  • Material reaction to calcium or sodium hypochlorite
  • Corrosion resistance
  • Proper installation

By not weighing this set of factors, the choice will be reflected in water losses as the infrastructures grow older. That is, actual and apparent water losses can also be a consequence of the choices made in the past.

The pipelines’ durability is also related to future renovation costs. Given that the Portuguese regulatory authority recommends the pipeline annual rehabilitation rate to be 1.2%, it is important that the materials have such longevity that they do not allow to age faster than the speed at which it is rehabilitated.

No less important is the reliability of the network, which is severely compromised if the installation is not carried out in accordance to the manufacturer’s recommendations, with rigorous on-site control and appropriate pipeline testing. Even good quality material will not be suitable if, after a poor installation or subject to service conditions for which it was not designed, will cause bursts and water losses.

Currently, there are certifications in Europe, within the pipeline installation sector, acknowledging the best practices of resources of installation and inspection companies. Therefore, contractors should be provided with knowledge and training in this area.

It is of extreme importance that after choosing the pipe materials to be applied in the network, the managing entity knows exactly why its choice and how to base it with concrete data.

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