Duplex Fasteners: Your Comprehensive Guide to Strength and Corrosion Resistance

Introduction

Ananka Group stands as an industry leader in the manufacture of Duplex Fasteners, offering a variety of size, grade, and spec high-quality Duplex fasteners. A manufacturer, stockist, supplier, and exporter, Ananka Group is focused on quality fasteners for demanding international industries from oil and gas to marine and construction applications. Duplex Fasteners are designed to withstand extreme strength and corrosion resistance conditions so that they can be used for demanding applications. We guarantee quality and strength throughout the range be it custom dimensions or specific grades, we get them to meet your particular needs in a project.

Duplex Fasteners are high-performance pieces made from duplex stainless steel, known for impressive strength and corrosion resistance. This structure of duplex stainless steel unites austenitic and ferritic structures with good mechanical properties and offers extreme durability even in very severe environment. Therefore, the applications where such conditions exist make Duplex Fasteners a favorite selection for oil and gas industry, chemical processing industries, marine applications, etc.

Duplex fasteners offer a much higher resistance to pitting and stress corrosion cracking as well as crevice corrosion, especially in chloride-rich environments, when compared with regular stainless steel fasteners. Their high strength-to-weight ratio also makes them quite popular for applications that involve high demand where weight saving and reliability are the word of the day.

More About Duplex Fasteners

Due to their unique properties, duplex fasteners are widely applied in a number of different industries.?

Here are a few key benefits that make them standout:

Resistance to Corrosion: High Chromium, Molybdenum, and Nitrogen make Duplex Stainless Steel resistant to pitting and crevice corrosion, especially in saline or acidic environments.

Strength: Duplex Fasteners have a higher strength than standard austenitic stainless steels such as 304 and 316. They are twice as strong as these grades and thus suitable for heavy-duty applications.

Temperature Resistance: The fasteners work efficiently at both low and high temperatures but perform more efficiently in moderately tempered temperature situations. They can tolerate the mechanical properties over a range of temperature without deformation.

Fatigue Resistance: The Duplex Fasteners' high strength along with ductility allows them to resist high-cycles stress, which enhances their fatigue resistance.

Cost-Effectiveness: Although the Duplex Fasteners will be more expensive when purchased, the long lifetime and the minimal maintenance means that they are the long-term cost-effective.

Specification of Duplex Fastener

The Duplex Fastener includes bolts, nuts, washers, screws, studs, etc. There are specifications of Duplex Fasteners based on their application, size, and design.

Following are some of the normal specifications:

Standard Grades :

Duplex 2205 (UNS S31803/S32205): Known for excellent corrosion resistance and strength.

Super Duplex 2507 (UNS S32750/S32760): Applied for a more extreme environment with higher resistance and strength

Diameter: M3 to M100 is available, but it is applied according to the usage.

Length: It depends on the application and type up to some meters in the case of threaded rods and studs.

Mechanical Properties

Yield strength is approximately 450-550 MPa in standard duplex, while for super duplex, it's 620 MPa and above.

Tensile Strength: 620–795 MPa.

Hardness: Duplex 2205 typically around 293 HB (Brinell Hardness) and up to 310 HB for Super Duplex.

Standards: Duplex Fasteners are usually manufactured under international standards such as ASTM, ASME, DIN, and EN to ensure the quality, reliability, and compatibility with other industrial parts.

Chemical Composition of Duplex Fasteners

The chemical composition is the main performance character for Duplex Fasteners and that includes strength, in addition to corrosion resistance. Here are two of the common duplex stainless alloys, whose composition is used for the fasteners, as presented below:

1. DUPLEX 2205/UNS S31803 / S32205

CR 21–23%,

NI 4.5–6.5%

MO 2.5–3.5%

N 0.08–0.20%

FE Rest

2. SUPER DUPLEX 2507/UNS S32750 / S32760

CR 24-26%

NI 6-8%

MO 3-5%

N 0.24-0.32%

FE Rest

High chromium and molybdenum content along with nitrogen makes these alloys resistant to localized corrosion such as pitting and crevice corrosion. This is very essential in offshore and other aggressive environments.

Applications of Duplex Fasteners

Duplex Fasteners are used in all applications where strength combined with corrosion resistance is a prerequisite.?

A few of the common industries and applications include:

Oil and Gas: Exploration, drilling, and refinery operations.

Chemical Processing: Equipment handling corrosive chemicals.

Marine Industry: Shipbuilding, docks, and underwater applications.

Construction: Structures exposed to harsh environments.

Water Treatment: Desalination plants, sewage systems, and chemical tanks.

Conclusion

Duplex Fasteners have found their place in industries demanding strength, durability, and corrosion resistance. Their exclusive properties make them suitable for harsh environments where both strength and resistance to multiple types of corrosion are equally balanced. Though the upfront cost is higher, the long-term savings are in the form of extended service life and minimal maintenance of Duplex Fasteners.

FAQs

1. What are Duplex Fasteners?

Duplex Fasteners are components made from duplex stainless steel, known for high strength, corrosion resistance, and fatigue resistance, making them suitable for demanding applications.

2. What is the difference between Duplex and Super Duplex Fasteners?

Super Duplex Fasteners contain more chromium, nickel, and molybdenum than the standard duplex, providing greater corrosion resistance and strength.

3. Can Duplex Fasteners be used in high-temperature applications?

Yes, Duplex Fasteners can be used in all temperature applications, though they work efficiently within moderate temperatures. Severe high temperatures will affect the mechanical properties.

4. Which sectors usually utilize Duplex Fasteners?

The oil and gas, chemical processing, marine, construction, and water treatment industries are most often utilizing Duplex Fasteners because they are more durable and do not degrade quickly in rough conditions.

5. Is it cost-effective to use Duplex Fasteners?

Though the initial cost is pricey, Duplex Fasteners are long term because of their durability and low maintenance, not prone to corrosion.