Duplex Steel Flanges

Duplex 2205 Flat Face Flange Manufacturers recommend this stainless steel grade for industrial applications such as chemical processing, transportation and storage – pressure vessels, tanks, pipes and heat exchangers, sewage scrubbing systems, cargo holds of ships and trucks, petroleum and natural gas exploration and processing equipment – pipelines, pipes and heat exchangers.

Other applications for 2205 flanges include use in marine and other high chloride environments, biofuel plants, pulp and paper industry – digesters, bleaching equipment, stock handling systems, and food processing equipment. Major industries using these Duplex 2205 flanges include asphalt upgrading plants, nuclear power (mostly seamless), heavy oil refineries, and petrochemicals and acids.

Chromium, molybdenum, nitrogen and nickel are the most important alloying elements, which have a significant effect on the mechanical, physical and corrosion properties of duplex stainless steels. Chromium is necessary to form a stable chromium passivation film sufficient to protect steel from mild atmospheric corrosion. The higher the chromium content, the better the corrosion resistance.

2205 Duplex Steel consists of a two-phase microstructure of ferrite and austenite. When it comes to the chemical composition of 2205 duplex steel flanges, they mainly contain 22% chromium, 3% molybdenum and 5-6% nickel in the form of alloyed stainless steel.

Chromium is a ferrite former, which means it promotes the BCC structure of iron. It also increases oxidation resistance at high temperatures. Higher chromium also promotes the formation of intermetallic phases, which are detrimental to duplex stainless steels and should be addressed.

We are one of the largest producers of duplex steel sliding flanges with good fatigue strength and high corrosion resistance. 2205 Duplex Steel Blind Flange is also known for its various mechanical properties, such as excellent resistance to cracking, pitting, and corrosion in harsh environments.

Molybdenum increases resistance to pitting and crevice corrosion. However, its content in duplex stainless steels is generally limited to less than 4% because Mo is also a ferrite former and can lead to unwanted intermetallic phases. Nitrogen improves resistance to pitting and crevice corrosion.

The chemical composition of Duplex F51 flanges contains carbon, chromium, manganese, molybdenum, nitrogen, nickel and phosphorus. Flanges are used in pressure systems and valve fittings.

It also greatly increases the strength as the most effective solid solution strengthening element. Nitrogen is a strong austenite former, and the addition of nitrogen greatly improves the toughness of dual-phase steels. It also delays the formation of intermetallic compounds enough to allow processing and fabrication of dual-phase steels. Nickel is an austenitic stabilizer that promotes the formation of the austenitic FCC structure, which contributes to the toughness of dual-phase steels.

For duplex stainless steel flanges, solution annealing at an appropriate temperature followed by immediate water quenching can achieve the best metallurgical austenite-ferrite phase balance. It is important to keep the time between leaving the furnace and water quenching as short as possible. This is to minimize heat loss from the flange, which can lead to precipitation of detrimental phases before water quenching to room temperature.

Duplex steels were introduced to the market as a means to address the problems associated with stress-related corrosion cracking caused by chlorine solutions. The chemical composition of the duplex flange material also makes flanges less prone to chlorine-induced pitting corrosion. These alloys are less expensive than nickel-based steels.

Since nickel is a commodity material, the cost of using alloys that have been heavily alloyed using alloys tends to be very expensive. Despite the low nickel content, Duplex 2205 flanges manage to exhibit several important properties due to the high content of molybdenum and chromium.

The chromium content is between 20-28%, which is why UNS S31803/ S32205 blind flanges undergo a phenomenon called passivation. In this phenomenon, a self-healing protective passivating oxide layer surrounds the flange making it resistant to oxidation.

Duplex stainless steel flanges are widely used in the offshore oil and gas industry where they are exposed to corrosive media. In the oil and gas industry, where media is transported quickly across channels, the components used here can wear out.

They help modify and even clean these process systems. The corrosion resistance and tensile properties of duplex steel sliding flanges are amplified compared to most stainless steel flanges.

Compared to the corresponding austenitic steels, they are more prone to precipitation of sigma phases, nitrides and carbides, leading to embrittlement and reduced corrosion resistance. Duplex steel pipe flanges are an ultra-steel suitable for use in highly corrosive conditions where very high mechanical strength is required.

Duplex steel sliding raised face flanges have high corrosion resistance in chloride-containing media, including seawater, making this grade ideal for deepwater umbilicals and a range of other oil and gas applications.

As a medium alloy steel, Duplex Blind Raised Face Flanges offer excellent corrosion resistance and twice the mechanical strength in most media compared to standard austenitic stainless steel ASTM 316L.

Dual-phase steel butt-welded raised face flanges provide excellent and consistent machinability for increased cutting speeds, reduced tool wear and set-up time.

The formation of intermetallic phases such as sigma phase in duplex steel flange flanges occurs in the temperature range of 600¡ãC – 1000¡ãC, and the decomposition of ferrite occurs in the temperature range of 350¡ãC – 500¡ãC ( 475¡ãC embrittlement).

The basic idea of dual-phase steel long butt weld flanges is to produce a chemical composition that makes a roughly equal mixture of ferrite and austenite. The chemical composition of duplex steel lap flanges is balanced to produce approximately equal amounts of ferrite and austenite under solution annealed conditions.

The high temperature strength of dual phase steel slip flanges is similar to alloy grade 430 in the temperature range of 950 to 1150¡ãC. However, the tensile strength of these flanges increases rapidly below 900¡ãC.

Duplex 2205 is a nitrogen enhanced duplex stainless steel designed to solve common corrosion problems encountered with 300 series stainless steels. “Duplex” describes a family of stainless steels that are neither fully austenitic (such as 304 stainless steel) nor purely ferritic (such as 430 stainless steel).

The structure of 2205 duplex stainless steel consists of a pool of austenite surrounded by a continuous ferrite phase. In the annealed condition, 2205 contains approximately 40-50% ferrite. 2205 is often referred to as the workhorse grade and is the most widely used grade in the duplex stainless steel family.

The advantage of the dual-phase structure is that it combines the advantages of ferritic alloys (resistance to stress corrosion cracking and high strength) with the advantages of austenitic alloys (ease of manufacture and corrosion resistance). The service temperature of 2205 duplex stainless steel should be limited to below 600¡ãF. Prolonged exposure to high temperatures can make 2205 stainless steel brittle.

For many applications where 300 series stainless steel is susceptible to chloride stress corrosion cracking, 2205 duplex stainless steel is a cost-effective solution. Stress corrosion cracking occurs when stainless steel is subjected to tensile stress while in contact with solutions containing chlorides. Elevated temperatures also increase the susceptibility of stainless steel to stress corrosion cracking.

The combination of chromium, molybdenum and nitrogen gives 2205 good resistance to chloride pitting and crevice corrosion. This resistance is extremely important for services such as marine environments, brackish water, bleaching operations, closed loop water systems and some food processing applications.

The high chromium, molybdenum and nitrogen content of 2205 provides better corrosion resistance than common stainless steels such as 316L and 317L in most environments. This exotic alloy is used in oil and gas exploration and is also used in the chemical processing industry .

Duplex stainless steel grades are named duplex because these duplex flange equivalent grades have a two-phase microstructure. This two-phase microstructure consists of ferritic and austenitic stainless steel-like grains. As the name suggests, the duplex construction gives this duplex stainless steel socket weld flange material a variety of attractive properties.

Most processing equipment uses Duplex 2205. Also used by industrial storage and transportation units. Pulp and paper digesters, liquid tanks and paper machines also use Duplex 2205. It is ideal for use in marine environments.