The care of aqueduct and sewer pipes requires prior analysis that allows the development of an efficient anticorrosive plan.
by Duván Chaverra Agudelo
The aqueduct and sewer sector is also part of the systems that must be analyzed in depth to protect circulation pipes and drinking water storage tanks from corrosion.
Among the most important reasons for carrying out an anti-corrosion project for this industrial sector are those of prolonging the useful life of pipes and tanks, and protecting water, if it is drinkable, from the harmful effects of corrosion.
The constant presence of water, bacterial corrosion and changes in temperature are some of the factors that force pipes to be lined to protect them. In an existing installation, environmental issues such as the type of humidity, proximity to the sea, or the working temperature where the installation was carried out, must be taken into account within the analysis of an anticorrosive project.
Luis Granes, director of international sales of Sauereisen, Inc, a company specialized in corrosion, commented that another problem that allows to identify the realization of a correct analysis is to find the systems of collection of city effluents in which sulfuric acid can be obtained in concentrations so high that they reach 60%.
The guest also highlights the differences that exist between a project of this kind compared to similar ones for different industries. "Part of the problem is based on the inconveniences that arise such as the infiltration of high water tables in the sewer systems, which must be solved first, before proceeding to place a protective coating. On the other hand, there is discomfort in car traffic and in the people who live in the areas adjacent to the works, which make everyone uncomfortable and affect. if it is possible to reduce the time in which discomfort is generated in the day to day of the people, it will be better for everyone, "explained the guest.
In concrete pipes the presence of corrosion is also remarkable, this type of ducts are used mostly for the transport and collection of domestic, industrial and rainwater wastewater, generating very aggressive environments that cause very strong corrosion pathologies (1).
But there are differences between the effects suffered by concrete pipes inside and outside. Inside, bacterial decomposition and acid effluents that come from discharges in homes and industrial sectors generate sulfuric acid. Outside, acidic media are produced because of soils and environments with high acidity.
As Luis Granes explains, in general all facilities are exposed to a greater or lesser degree to corrosive attack by acid condensation, as well as abrasion by particles traveling in effluents, visitor mouths, lifting stations, collection wells, collection lines, treatment plants, aeration and decantation pools, among others; everything is exposed to attack by acids, abrasion or by the combination of both.
The above are some aspects that differentiate this sector of aqueducts and sewers with other anticorrosive projects. And this is important for selecting the type of coating that will protect the pipes.
In this regard, Luis Granes explains that the most recommended type of coating is the epoxy: "100% solid epoxy systems are ideal, since they do not have solvents in their formulation, they allow a return to service very quickly. On the other hand, epoxies have the benefit that they are easy to repair and this is an important aspect in case problems arise. Its adhesion on the substrate is more than guaranteed and does not generate the problems that other systems have, such as welds in the joints or anchors on the substrate. In addition, epoxies can be applied with Airless Spray, Plural Component or Trowel or Spoon systems, which makes them very versatile."
Another important issue of epoxy systems is that for their application it is necessary that the preparation of the surface is correct, since these reubrations have very low wetting or penetrating power in the pores (2).
As for the systems of application of the materials, these are basically used to restore the physical integrity of the concrete structures, through gunning systems, launching or projection systems or the classic formwork.
Maintenance
In the maintenance process, the environmental factor plays a fundamental role. Our guest explains the reasons: "The coatings in the city effluent collection systems have the limitation that if there is a rainy season it is not possible to work, since you can not take the facilities out of service. If the water flows are very high, you can not do the bypasses and therefore, the work becomes impossible. In most cases, it is expected until the arrival of the dry season, which guarantees us low effluents, more manageable and greater safety for the workers who are preparing to do the installation."
Finally, it is important to mention two more key issues in anti-corrosion projects for this class of industries: the first has to do with the number of inspections that are made to a system after the execution of the project. The professional of the company Sauereisen says that "the inspections will depend on the system that is installed. The durability of epoxy systems, from our experience, exceeds 28 years, since our oldest work and with more years of service has been running smoothly for more than that number of years. This gives an idea of the durability of epoxies in this class of environments."
The guest concludes by highlighting that regulations should be stronger in our region, in order to encourage industries to invest what is necessary in anti-corrosion projects of this type.
"Many companies, both in the United States and around the world, have a tendency to try to bypass laws and regulations. In some countries, rules and standards are stricter and many companies are forced to comply with them. Here in the United States, by mandate of the EPA (Environmental Protection Agency), work is being done at the state, city, mayor's and municipal levels on the separation, restoration and coating of city and rain effluent collection systems, with the condition that if this new ordinance is not complied with, States that do not accede to it will not receive further subsidies. This has pushed everyone to review their facilities and proceed to make the necessary changes and improvements."
References
(1) http://www.docentes.unal.edu.co/jmlizarazom/docs/Compat.pdf
(2) http://tesis.uson.mx/digital/tesis/docs/11596/Capitulo5.pdf
Leave your comment