Plastic? It's just fantastic

The water industry was quick to embrace plastic pipework. But its versatility isn't always recognised, says James Roper.

MORE THAN half of all pipework systems installed within the water treatment industry are plastic. Yet despite this sector being one of the first markets to truly embrace the benefits of plastic pipework systems, there is still a degree of education needed.

In contrast to other sectors, where traditional metal systems remain the material of choice, the water industry adopted plastics immediately and has been confidently using these systems for more than 50 years. The number of plastic system users is steadily increasing year-on-year as more and more end users and contractors are introduced to the benefits of more innovative systems.

However, there are still those within the industry who have the opinion that plastic is plastic, and that all plastic systems are the same. This is simply not the case and, in fact, there are a whole host of purpose-designed plastic pipework systems, each specially manufactured to cater for specific applications.

Within water and wastewater treatment plants, there are a variety of applications that all have different requirements, from transporting wastewater to chemical treatment of water and the production of pure water from wastewater. As a result, the industry needs different systems, each with specific properties, to cater for the materials that are used in each process and this is exactly what plastic systems can offer.

Performance
Polypropylene has the broadest range of properties, enabling it to safely transport a variety of substances within a wide operational temperature range. It has excellent chemical and abrasion resistance, allowing it to convey a whole host of chemicals including acidic and caustic fluids.

This excellent chemical resistance makes it the ideal solution for systems that may have unknown chemical combinations passing through them. Due to its socket fusion welding jointing technique, as well as the innovative properties of polypropylene, this system is also one of only a few plastic materials that can safely convey any type of solvent or solvent contaminated effluents.

While it has exceptional performance capabilities, the only downside of jointing polypropylene is that, compared with solvent welding, more specialist equipment is needed to perform either a socket or butt fusion joint.

Other plastic systems that are solvent welded, such as ABS, PVC-U and Corzan (C-PVC), offer significant time and cost savings during the installation process due to the quick and easy nature of the jointing technique. As a result, these systems are always recommended when there are strict deadlines or tight budgets in place.

Solvent welded systems, in most cases, have a higher pressure rating so are the most appropriate systems for applications which need to convey fluids at high pressures.

Each of these solvent welded materials has been purpose-designed to cater for specific applications, so all have different strengths, with PVC-U and Corzan (C-PVC) materials specially designed for chemical dosing processes. PVC-U has excellent chemical resistance and is the ideal material to transport chemicals such as acids and alkalis, up to 60°C, that are used for chemical treatment processes in water treatment works. Corzan (C-PVC) also has excellent chemical resistance but can cope with much higher temperatures, up to 100°C. It has increased chemical resistance to certain chlorinated chemicals that are used within various disinfection processes, as well as many other bespoke applications.

There are slight differences in the chemical resistance properties of PVC-U and C-PVC, so contractors and specifiers should seek advice from the technical support team on the best material to convey specific chemical solutions.

Versatile
When pipework is required to carry chemically contaminated water, but not to dose chemical concentrates, ABS is the most versatile material. It has excellent impact strength and durability, particularly when operating at low temperatures, making it a robust system for busy water treatment plants.

Available in bore sizes up to 315mm, ABS is an ideal solution for the mass movement of contaminated water and sewage. ABS is also the perfect system for the development of pure water via reverse osmosis or other clean water processes. The smooth bore and lack of plasticisers ensures that no limescale or contaminants can build up in the system, ensuring that water remains pure throughout the lifetime of the system.

Plastic pipework systems offer many benefits for the water and waste treatment industry and Durapipe UK is advising that there are several purpose-designed systems specially developed to cater for water treatment processes.

A one system fits all approach cannot possibly be adopted within water and wastewater treatment plants, the individual applications all have different requirements so need specially designed systems that can meet these.
The flexibility and choice with plastic pipework systems will ensure that water treatment plants can implement a cost effective and highly efficient system.

James Roper is brand manager at Durapipe UK. T: 01543 279909

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