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Pre-sale Service
Our company can provide 24-hour service to discuss product parameters, prices, delivery dates, transportation and other details with customers.
Quality Solution
If it is confirmed that the quality loss is caused by us, we will reissue the unqualified product or make a cash compensation.
Our History
Was established in 2006, located in Cangzhou City, Hebei Province, China. We have more than ten years of export business experience.
Production Market
Our company's business covers the Middle East, North Africa, South America, Southeast Asia, Central America and other regions, with an annual export value of more than 10 million US dollars.
Duplex stainless steel pipes are a type of stainless steel pipe that are known for their strength, corrosion resistance, and durability. They are made from an alloy of ferrous metal that is about 50% iron and are also known as austenitic-ferritic stainless steel.
Stainless steel welded tube, referred to as welded tube, is a steel tube made from commonly used steel or steel strips, which are crimped and formed by units and molds. The production process of welded steel tube is simple, with high production efficiency, numerous varieties and specifications, and requires relatively small equipment investments, although its general strength is lower than that of seamless steel tube.
Stainless steel welded tubes are categorized into straight seam welded tubes and spiral welded tubes based on the type of welds. According to their specific applications, they are further classified into general welded tubes, heat exchanger tubes, condenser tubes, galvanized welded tubes, oxygen blown welded tubes, wire casings, metric welded tubes, idler tubes, deep well pump tubes, automobile tubes, transformer tubes, electric welding thin-wall tubes, electric welded shaped tubes, and spiral welded tubes.
S31500 Duplex Stainless Steel Pipe
The main feature of duplex stainless steel is that its yield strength can reach 400-550 MPa, which is twice that of ordinary stainless steel. This characteristic allows for material savings and reduced equipment manufacturing costs. In terms of corrosion resistance, especially in harsh environments (such as seawater with high chloride ion content), duplex stainless steel exhibits significantly better resistance to pitting corrosion, crevice corrosion, stress corrosion, and corrosion fatigue compared to ordinary austenitic stainless steel, and its performance is comparable to that of high-alloy austenitic stainless steel.
S32205 Duplex Stainless Steel Pipe
Duplex stainless steel pipe has good welding performance. Compared with ferritic stainless steel and austenitic stainless steel, it does not exhibit the welding heat-affected zone issues seen in ferritic stainless steel, where severe grain coarsening greatly reduces plasticity and toughness. It is also less sensitive to welding hot cracking than austenitic stainless steels.
S32750 Duplex Stainless Steel Pipe
Duplex stainless steel is called "duplex" because its metallographic microstructure consists of two types of stainless steel grains, ferrite and austenite. The strength of duplex stainless steel is about twice that of conventional austenitic stainless steel or ferritic stainless steel and has good plasticity and toughness. In most application environments, duplex stainless steels show high corrosion resistance and resistance to stress corrosion cracking (SCC).
S32760 Duplex Stainless Steel Pipe
Duplex stainless steel pipes are primarily used in the following applications: neutral chloride environments, oil refining industry, petrochemical and chemical industries, chemical industry pipelines, oil and gas industry, pulp and paper industry, fertilizer industry, urea industry, phosphate fertilizer industry, seawater environments, energy and environmental protection industries, light industry, food industry, and the food and pharmaceutical industries.
N04400 Nickel Alloy Steel Tube
N04400 nickel alloy, also known as Monel alloy, is an alloy made of metal nickel as the base and adding copper, iron, manganese and other elements. It has good corrosion resistance in seawater, chemical solvents, ammonia sulfur chloride, hydrogen chloride, various acidic media such as sulfuric acid, hydrofluoric acid, hydrochloric acid, phosphoric acid, organic acids, alkaline media, salt and molten salt. N04400 nickel alloy also has good mechanical properties, good welding performance and medium and high strength in a wide range of service temperatures from low temperature to high temperature.
N06600 Nickel Alloy Steel Tube
N06600 alloy, also known as Inconel 600, is a nickel-chromium-iron alloy that is both corrosion-resistant and heat-resistant. N06600 exhibits good corrosion resistance in acetic acid, formic acid, stearic acid, and other organic acids, while showing moderate resistance to inorganic acids. Its outstanding feature is the ability to resist corrosion from dry chlorine gas and hydrogen chloride, with an application temperature reaching up to 650°C. At high temperatures, annealed and solution-treated N06600 alloys demonstrate good resistance to oxidation spalling and maintain high strength in air.
N06601 Nickel Alloy Steel Tube
N06601 is a nickel-based alloy material, also known as Inconel 601 alloy. It is mainly composed of nickel and chromium, but also contains elements such as iron, aluminum and titanium. N06601 has excellent properties such as anti-oxidation, anti-corrosion and high temperature resistance, so it is widely used in chemical industry, petrochemical industry, aerospace, nuclear industry and other fields. N06601 is suitable for high temperature, high corrosion, high strength and structural materials not affected by creep, such as heat exchangers, furnace tubes, reactors, etc.
Corrosion Resistance
Duplex SS contains about 20% of chromium in addition to the molybdenum content. Together, these elements make duplex stainless steel grades extremely resistant to severely corrosive environments. Duplex and Super duplex grades of stainless steel can withstand crevice, pitting, chloride ion, and stress corrosion even at elevated temperatures.
Machining Properties
Duplex Stainless Steel grades have great fatigue strength and superior mechanical properties.
Heat resistant and hot-working range
Duplex stainless steel grades are resistant to heat and high-temperature environments. Duplex Steel UNS S31803 Pipes and Tubes do not necessarily require forging, they can be rolled directly. However, in high heat environments, it is tougher to work with chromium alloys than austenitic alloys. Thus, it is easier to hot-roll duplex SS pipes that have low chromium content.
Weldability
Duplex SS grades have superior weldability. These pipes do not crack easily under pressure and heat influence. Preheating the material before the welding process is not required in the case of Duplex SS Pipes.
Thermal Conductivity and Expansion
When Duplex SS pipes are compared to austenitic grades of SS pipes such as 304 and 316, it is observed that Duplex pipes have proven to have better thermal conductivity with a lower rate of expansion. This property of incredible thermal conductivity makes Duplex SS pipes appropriate for applications in composite plating and as the core element in a heat exchanger.
Applications of Duplex Stainless Steel Pipe
Offshore platforms
Used in topside piping, fire water systems, and seawater cooling systems.
Subsea pipelines
Employed for transporting oil and gas in corrosive marine environments.
Processing equipment
Utilized in heat exchangers, pressure vessels, and separators.
Downhole applications
Used in tubulars and completion equipment where high strength and corrosion resistance are crucial.
Chemical processing
Chemical transport
Used for piping systems carrying corrosive chemicals.
Reactors and vessels
Employed in the construction of process equipment handling aggressive media.
Heat exchangers
Utilized where high thermal conductivity and corrosion resistance are required.
Storage tanks
Used for storing various chemicals and intermediate products.
Reverse osmosis systems
Used in high-pressure pumps and piping for seawater desalination plants.
Brine handling
Employed in piping systems for concentrated salt solutions.
Water distribution
Utilized in large diameter pipes for potable water systems, especially in coastal areas.
Wastewater treatment
Used in various stages of wastewater processing plants.
Pulp and paper industry
Digesters
Employed in the construction of vessels used for pulping wood chips.
Bleaching equipment
Used in piping and vessels for corrosive bleaching chemicals.
Recovery boilers
Utilized in high-temperature, high-pressure applications in the recovery process.
General mill piping
Used for various process fluids throughout paper mills.
Brewing tanks
Employed in the construction of fermentation and storage vessels.
Dairy equipment
Used in milk processing and cheese-making equipment.
Fruit juice processing
Utilized in piping systems for acidic fruit juices.
General food processing
Used in various stages of food production where hygiene and corrosion resistance are paramount.
Offshore and marine applications
Seawater systems
Used in cooling water pipes, firefighting systems, and desalination plants on ships and offshore platforms.
Propeller shafts
Employed in marine propulsion systems.
Offshore wind turbines
Utilized in structural components and piping systems for offshore wind farms.
Port facilities
Used in jetty piping and loading arms for corrosive environments.
Structural applications
Employed in bridges, particularly in coastal areas or where de-icing salts are used.
Façade support systems
Used in exterior cladding support structures for buildings.
Reinforcement bars
Utilized in concrete structures in marine environments or exposed to de-icing salts.
Swimming pools
Used in pool piping systems and supporting structures.
Properties Of Duplex Stainless Steel Pipe
Strength: Duplex stainless steels are about twice as strong as regular austenitic or ferritic stainless steels.
Toughness and ductility: Duplex stainless steels have significantly better toughness and ductility than ferritic grades; however, they do not reach the excellent values of austenitic grades.
Corrosion resistance: As with all stainless steels, corrosion resistance depends mostly on the composition of the stainless steel. For chloride pitting and crevice corrosion resistance, their chromium, molybdenum and nitrogen content are most important. Duplex stainless steel grades have a range of corrosion resistance, similar to the range for austenitic stainless steels, i.e from Type 304 or 316 (e.g. LDX 2101©) to 6% molybdenum (e.g. SAF 2507©) stainless steels.
Stress corrosion cracking resistance: Duplex stainless steels show very good stress corrosion cracking (SCC) resistance, a property they have "inherited" from the ferritic side. SCC can be a problem under certain circumstances (chlorides, humidity, elevated temperature) for standard austenitics such as Types 304 and 316.
Cost: Duplex stainless steels have lower nickel and molybdenum contents than their austenitic counterparts of similar corrosion resistance. Due to the lower alloying content, duplex stainless steels can be lower in cost, especially in times of high alloy surcharges. Additionally, it may often be possible to reduce the section thickness of duplex stainless steel, due to its increased yield strength compared to austenitic stainless steel. The combination can lead to significant cost and weight savings compared to a solution in austenitic stainless steels.
Due to its special advantages, duplex stainless steel is widely used in petrochemical equipment, seawater and wastewater treatment equipment, oil and gas pipelines, paper-making machinery and other industrial fields. In recent years, it has also been used in the field of bridge bearing structure, with a good development prospect.
Properties of Duplex Stainless Steel Pipe
The unique microstructure of duplex stainless steel pipes results in a combination of properties that make them suitable for a wide range of applications. Understanding these properties is crucial for determining the suitability of duplex stainless steel pipes for specific use cases.
High strength
Duplex stainless steel pipes exhibit significantly higher yield strength compared to austenitic stainless steels.
This high strength allows for reduced wall thickness in many applications, leading to weight savings and potentially lower material costs.
The increased strength also provides better resistance to external pressures and structural loads.
Good ductility and toughness
Despite their high strength, duplex stainless steel pipes maintain good ductility.
They offer excellent toughness, especially at low temperatures, making them suitable for cryogenic applications.
The combination of strength and toughness contributes to their resistance to fatigue and impact.
General corrosion resistance
Duplex stainless steel pipes offer excellent resistance to general corrosion in various environments.
Their high chromium content forms a protective passive layer, similar to other stainless steels.
Resistance to chloride pitting and crevice corrosion
The balanced microstructure and alloying elements (particularly molybdenum and nitrogen) provide superior resistance to localized corrosion.
This makes duplex stainless steel pipes especially suitable for marine environments and chloride-containing process fluids.
Stress corrosion cracking resistance
Duplex stainless steel pipes show excellent resistance to stress corrosion cracking, particularly in chloride-containing environments.
This property is crucial in applications where high stresses and corrosive environments coexist.
Duplex stainless steel pipes generally have good weldability, better than fully ferritic grades.
Proper welding procedures and filler materials are essential to maintain the phase balance and corrosion resistance in the weld zone.
Post-weld heat treatment is often not required for most duplex grades, which can simplify fabrication processes.
Duplex stainless steel pipes perform well in a wide range of temperatures, typically from -50°C to 300°C.
At higher temperatures (above 300°C), the ferrite phase can become brittle, limiting their use in high-temperature applications.
For cryogenic applications, specific grades of duplex stainless steel are available that maintain good toughness at very low temperatures.
These properties make duplex stainless steel pipes an excellent choice for many demanding applications, especially where a combination of high strength and corrosion resistance is required. However, it's important to consider the specific grade of duplex stainless steel and the exact requirements of the application when making material selections.
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Our Factory
Our company's business covers the Middle East, North Africa, South America, Southeast Asia, Central America and other regions, with an annual export value of more than 10 million US dollars.
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