How innovative engineering helps Chile's desal ambitions

While desalination plants have become more popular in light of the drought afflicting Chile, concerns emerged, specifically on distribution systems as the most expensive aspects.

BNamericas talks with Francisco Pizarro, Chile and Brazil manager of pipe manufacturer AGRU, about solutions and prospects.

BNamericas: What solutions to water transport and piping cost are under development?

Pizarro: In recent years, materials engineering has become more sophisticated, reaching thermoplastic and fluoropolymer materials that are now strongly present in the desalination industry. This is thanks to their low weight, flexibility, easy installation, competitive cost and high performance compared to mechanical, thermal and chemical agents.

BNamericas: What particular challenges do desalination pipelines pose?

Pizarro: At the submarine level, intakes and discharges require increasingly larger diameters and with different nominal pressures.

Increasingly complex segmented and special pieces [spools] are being used in reverse osmosis plants, which also enable handling relatively complex flows in terms of abrasion and concentration.

For pretreatment filters, materials engineering is recommending [polypropylene] parts with better mechanical properties due to their performance against abrasion and higher pressures.

With regard to more specific areas, such as chemical process tanks, it is necessary to use purer raw materials capable of resisting high chemical aggressiveness, such as sulfuric acid and sodium hypochlorite. In this case, pipes and fittings made of PVDF [polyvinylidene fluoride] or ECTFE [ethylene chlorotrifluoroethylene] are essential to ensure useful life.

BNamericas: How much potential does Chile’s desalination sector offer?

Pizarro: The potential is huge as there is an obvious transition away from less efficient raw materials such as steel or fiberglass reinforced plastic [GRP]. High-density polyethylene [HDPE] is more flexible, about 50% lighter, safer and more efficient when welding, and more efficient in flow transmission versus GRP.

The same dynamic happens versus steel: HDPE has advantages regarding corrosion resistance, flexibility, weight and therefore ease of installation.

In all areas within a desalination plant, AGRU plays a key role as it participates in the design, manufacturing and markets the pipes and connections suitable for each of the challenges.

AGRU is the biggest manufacturer of large diameter extruded pipes of up to 3,500mm in PE 100-RC, which is the most advanced polyethylene, with greater resistance to cracking.

AGRU also manufactures polypropylene tubes and connections, in addition to the rest of the range of fluorinated materials such as PVDF and ECTFE, as well as ultra-pure materials such as FEP [fluorinated ethylene propylene] and PFA [perfluoroalkoxy]. With all these raw materials, it is feasible to manufacture special parts, filters, diffusers, ventilation chambers, etc.

BNamericas: What projects are you eyeing in the country in terms of water pipelines?

Pizarro: Many and varied projects.

In mining, for example, there is a water pipeline project between operations to ensure the operational subsistence of one of them. As it is an extensive layout, sand beds can be avoided by installing PE 100-RC, taking advantage of its cracking resistance characteristics.

In mining, a lot of pipes with factory mutual certification are also being implemented for fire networks and AGRU actually has this certification.

In agriculture, there is the extensive project of the water highway, which theoretically would allow the transport of excess water from the south to the north.

And in the sanitary area projects are more varied, but they all involve effluent treatment.

In all projects, we have paid particular attention since they require support infrastructure but with high-level operability for easy installation, quality to ensure useful life and technical support in the field.

BNamericas: What’s your view on authorities’ demand that environmental aspects be analyzed in separate processes, as happened with the ENAPAC desalination project?

Pizarro: In this area, I would like to not answer since I do not have all the details for accurate and informed judgement.

I only know that the environmental authority in Chile has historically been characterized by carrying out the analyses and making the most judicious decisions possible.