Duplex tube

Recommended grades

Duplex seamless tube suppliers in UAE

What are ID and OD in duplex tubing?

The primary dimensions involved in measuring duplex pipes are ID and OD, where the former refers to the inner diameter of the tube. The OD is the outside diameter. For example, standard sizes of a duplex steel tube can offer outer diameters of 1/8″ to 8″. Accordingly, the schedule can vary from SCH 5 to SCH 160. Pipes get referred to by the nominal size or NPS, which relates to the outside diameter. However, the two values are different.
Duplex pipes often have good ductility and can get moulded in desired shapes and sizes. Measuring these parameters is crucial for selecting the best component for your installation, for instance, duplex stainless square tubing.

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Does a duplex steel tube rust?

Duplex piping is highly corrosion resistant. It does not rust easily from harsh chemicals like chlorides and sulphides. A duplex stainless steel tube is also resistant to cracking induced by stress, i.e., in the presence of factors like a corrosive environment and a high temperature. Also, since this material has high chromium, it can resist pitting corrosion. It has an impressive PREN or Pitting Resistance Equivalent Number.
Duplex piping displays high heat conductivity and can work at low temperatures, exhibiting low thermal expansion. The structural integrity and protection against damage make it befitting for high-temperature, abrasive applications like chemical manufacturing and a stainless steel duplex heat exchanger tube.
However, prolonged exposure to corrosive agents will cause rust to develop. You must take this into account when planning maintenance and downtime.

Duplex stainless steel tubes and DSS boiler tubes are known for very good stress corrosion cracking

Is duplex tube material suitable for water desalination plant & seawater?

Duplex components have a 50/50 microstructure of austenite and ferrite grades. This tubing frequently features in marine applications due to its corrosion resistance. Duplex tubing can work in pipes used for water desalination as it does not rust when exposed to seawater. The most common applications are in water distribution, wastewater treatment, and environments with chloride and phosphoric acid.
A considerable advantage of this grade is the lower nickel and higher molybdenum content, which makes it affordable. The weight savings concerning enhanced chemical properties are significant. Duplex piping can get employed above and underwater. It offers dependable performance in different weather conditions.

Most popular types of Duplex tube

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Are duplex tubes weldable?

Duplex piping showcases good weldability. You can employ standard welding processes based on your requirements. A duplex steel welded tube can work at temperatures exceeding 1000 degrees Fahrenheit. In this context, many applications can benefit from welded duplex piping. You can weld it to other duplex steels, carbon steel, austenitic stainless steel, etc.
However, it is not as straightforward to perform compared to austenitic grades. The ease of welding gets impacted by parameters like heat input. You have to consider the strength of the weld metal for dss superheater tubes, i.e., assess the lower of the parent steels.

Purchase duplex stainless steel extruded tube and welded tube that complies with standards in a variety of sizes and custom lengths

Can you heat treat a duplex seamless tube?

Piping can undergo different heat treatments depending on the customer requirements. However, it is generally limited to production. A duplex seamless tube undergoes solution annealing at 1040 degrees Celsius. Manufacturers decide the hold time based on thickness. It gets followed by quenching in water.
The piping does not get heat treatment after welding. Any subsequent procedure on a duplex stainless steel extruded tube can lead to the formation of inter-metallic phases at different temperatures. For instance, you will see sigma phase formation at 600-700°C. Solution annealing and quenching is possible but inconvenient for welded components.

For what is a duplex stainless steel tube used?

These tubes have multiple applications in industries like chemical processing, oil and gas, and pollution control. They also work in heat-based components like heat exchangers, a duplex boiler tube, and cooling pipes. Other uses include paper manufacturing and marine equipment. This material also has good yield strength and can be cost-effective for applications like pressure vessels and storage tanks.
The bulk of applications emanates from the high corrosion resistance and thermal properties of duplex piping. It is common in plumbing systems that benefit from its durable structure. It also gets used in desalination, construction, and brewing tanks.