In the water treatment field, plants reliability depends on the quality of each component. Among them, tubes play a crucial role because they are responsible for the safe transportation of fluids, chemical reagents and process water in high corrosive contexts, variable pressures and where there are more and more strict continuity requirements.
To satisfy these aspects, the market addresses towards special tubes in stainless steel and high performant alloys, designed to offer the best resistance, durability and reliability over time and operating cost optimization.
Among the main types of tubes used in this field we can find stainless steel, carbon steel, PEAD (high density Polyethylene) and PVC. Each of them has got specific features letting them to be more or less suitable for the different applications.
Stainless steel is often the best choice in those parts of the plants subject to high corrosion or where high hygiene standards are required for the treatment of water for sensitive applications and for recycling. It guarantees an excellent resistance to chemical agents and it has got long-lasting life, reducing the expenses related to substitutions and extraordinary maintenance. In addition, it has got an excellent mechanical resistance to high pressures and continuous stress. Furthermore, it is a 100% recyclable material perfectly in line with the environmental sustainability principles.
In AISI 316L steel the presence of Molybdenum highly improves its corrosion resistance in comparison with AISI 304. Thanks to this characteristic, it is widely used for water treatment plants where tubes are exposed to chlorides, chemical substances and particularly corrosive atmospheres.
Nevertheless, there are particularly critical applications in which also 316L stainless steel may require more performant solutions.
In these cases, special materials are used:
- Duplex and superduplex, characterized by a high mechanical and corrosion resistance
- Inconel, for high temperature environments and severe chemical aggression circumstances
- Hastelloy, in critical chemical contexts
- Nickel alloys and highly performant materials for specific project requirements
Since stainless steel is a highly performant material, the initial investment is higher compared to other materials.
An alternative to stainless steel remains carbon steel chosen for its excellent mechanical resistance and because it is cheaper.
Not considering only steel solutions, nowadays the material used for water treatment plants are PEAD (high density Polyethylene) and PVC.
The first one offers a high chemical agents and corrosion resistance, it is lightweight and easy to install requiring a shorter setting time. For these reasons, it is widely appreciated for underground networks and fluid transport. Nevertheless, it doesn’t resist very well to high temperatures compared to metal materials.
The second one is a proven solution for water applications. It is lightweight, corrosion resistant and cheaper being particularly useful for standard operating conditions plants. In comparison with PEAD and steel it is has got a lower mechanical resistance; in fact, it is less resist to important vibrations and it is very sensitive to high temperatures.
Regarding the dimensions to use, the tubes can have small diameters typically used for instrumentation and chemical dosing or big diameters usually used for high-capacity pipe.
The choice of the diameter depends on the capacity, on the type of the fluid and on the specific part of the plant. Nevertheless, practical experience shows that certain diameters are particularly used.
More specifically, for chemical dosing systems and ancillary services the most used diameters are from ND 25 to ND 80.
For the main networks and process lines, the most common diameters are: ND 100,200,250,300.
For big plants and for systems used to transport high water flow rates and sludge lines, bigger diameters are required: ND 400,500,600 etc.
At the same time, instrumentation tubes are more and more frequently required in control systems, and in automation for the most modern plants.
Besides the usual nominal diameters, instrumentation pipes in inches are widely used with external diameters of 6, 8, 10 and 12 mm used for control systems, automation and chemical dosing.
Generally speaking, for modern water treatment plants, the most used solution is now PEAD; while for aggressive chemical fluids, substances and contexts stainless steel is still the preferred choice because it is the material that has got the best performant features for this applications.
When choosing the most suitable tubes, there is not a type that prevails over the others ones; it always depends on the characteristics of the fluid, on operating conditions, pressure and durability aims over the time.
Tecra, specialized in the supply of stainless steel tubes, offers its experience also in the water treatment field supporting project managers and engineers, EPC contractors and plant managers in the supply of stainless steel and special materials tubes for the most demanding applications.
Refer to proper designing and selection of the most suitable material, but also to a reliable partner such as Tecra means investing in the plant quality, in efficiency, safety and operational continuity in the long term.
Want to identify the type of tubing best suited to your water treatment plant? We are available to assess the specific requirements of your project and support you in selecting the most suitable material. Contact us!