What are SA 789 UNS S31803 Tubes? Properties, Use and Composition

What are SA 789 UNS S31803 Tubes? Properties, Use and Composition.

Do you have questions about SA 789 UNS S31803 tubes? Do you need this type of tube and want to ensure it meets your specific requirements? You’ve come to the right place! This blog post will cover everything from what these tubes are to their properties and composition, plus how they can be used for various applications. You will comprehensively understand SA 789 UNS S31803 tubes with all the information provided here. So, let’s jump right into it!

This blog post details the properties, uses, and composition of SA 789 UNS S31803 tubes. Whether you’re an engineer, a contractor, or simply someone interested in the science of steel, this post is for you. So, please grab a cup of coffee, sit back, and let’s dive into the world of SA 789 UNS S31803 tubes.

Properties of SA 789 UNS S31803 Tubes

SA 789 UNS S31803 tubes are austenitic, duplex stainless steel alloys designed for excellent corrosion resistance and strength. The alloy offers both ferritic and austenitic microstructures, which make it highly resistant to stress cracking, pitting, crevice corrosion, chloride-induced stress corrosion cracking and general corrosion in a variety of environments, including fresh water, seawater and acidic media. It also exhibits high strength properties up to 550MPa and excellent mechanical properties such as ductility, toughness and formability. It is commonly used in the oil & gas industry and marine applications because it can perform under extreme conditions without succumbing to degradation or loss of integrity over extended periods.

Uses of SA 789 UNS S31803 Tubes

SA 789 UNS S31803 tubes are typically used in applications involving seawater, acid and chloride-bearing environments due to their superior corrosion resistance. They are regularly employed in chemical processing, oil & gas pipelines, desalination pipes, pulp & paper plants, and other areas requiring welded Austenitic stainless steel tubing. The material is also commonly found in constructing condensers and heat exchangers, where it can be relied upon for its excellent strength at high temperatures and good pressure containment capacities. Additionally, the combination of chromium-nickel-molybdenum content helps support nonmagnetic properties when used in magnetic materials such as MRI scanners or surgical tool components.

Composition of SA 789 UNS S31803 Tubes

SA 789 UNS S31803 Tubes are composed of austenitic stainless steel and have a dual-phase microstructure. This grade contains a higher percentage of chromium and nickel than the 304 grade, making it more corrosion-resistant. SA 789 UNS S31803 Tubes contain around 18 to 20% chromium, 9 to 12% nickel, 2.5 to 3 % molybdenum and only trace amounts of other elements such as carbon, silicon, manganese and nitrogen. Nickel gives this alloy superior corrosion resistance properties, while the molybdenum helps prevent pitting in chloride environments. The tubes are usually cold drawn for use in low-temperature applications and typically feature high tensile strength as well as excellent weldability characteristics due to their composition of austenitic stainless steel material with low carbon content, making them suitable for welding without post-weld heat treatment or PWHT requirements.

Maintenance and repair of SA 789 UNS S31803 Tubes

Like all types of steel, SA 789 UNS S31803 tubes require regular maintenance and repair to ensure optimal performance and longevity. One of the main challenges with maintaining duplex stainless steels like SA 789 UNS S31803 is preventing corrosion in welds and heat-affected zones.

To prevent corrosion in these areas, it’s important to use welding techniques that minimize heat input and avoid the use of filler metals with high carbon content. Additionally, it’s important to conduct regular inspections to identify and repair any corrosion or damage before it becomes a serious problem.


In summary, SA 789 UNS S31803 tubes are a type of steel tube that is known for its high strength, excellent corrosion resistance, and affordability. These tubes are made from duplex stainless steel with a unique microstructure of austenite and ferrite, providing superior toughness and corrosion resistance.

SA 789 UNS S31803 tubes are used in various industries and applications, such as chemical processing, oil and gas, and pharmaceuticals, and require regular maintenance and repair to ensure optimal performance and longevity. If you want to learn more about SA 789 UNS S31803 tubes or need assistance with their maintenance or repair, contact a reputable steel supplier or engineering firm for more information.