Duplex Steel Fasteners

Duplex steel fasteners are dual-phase threaded components manufactured from an austenitic-ferritic stainless steel microstructure, commonly known as 'duplex fasteners'. The chemical composition of these fasteners includes 21–23% chromium, 4.5–6.5% nickel, 2.5–3.5% molybdenum, and controlled additions of nitrogen balanced to achieve a 50/50 phase ratio. This composition has a tensile strength of 620-795 MPa and a yield strength roughly twice that of standard 316 stainless steel. These Duplex Steel Fasteners are highly resistant to chloride stress corrosion, cracking, pitting, and crevice corrosion, as well as high mechanical strength and toughness. They are commonly used in oil and gas plants, marine structures, chemical processing units, and water treatment facilities where standard austenitic stainless steel grades are not suitable.

Duplex Steel Fasteners Prices

The price of duplex steel fasteners depends on grade, dimensions, market conditions, and order volume.

Approximate Price Range

The price of duplex steel fasteners ranges between Rs 525 and Rs 750 per kg. Standard hex bolts and nuts in regular sizes sit near the base of that range. High-pressure and custom configurations carry a premium.

Factors Affecting Price

The price of duplex fasteners depends on several factors; alloy grade is one of the key factors, as Duplex 2205 (UNS S32205) is more expensive than UNS S31803 due to its higher nitrogen and molybdenum content requirements. The cost of fasteners is also influenced by their size and design, as larger bolts and longer stud bolts require more raw material. Order quantity affects pricing as well; the fluctuations in rates of nickel and molybdenum can directly impact the final price. In addition, requirements such as mill test reports (MTRs), third-party inspections, NACE MR0175 compliance, and special surface finishes add to the total cost.

Duplex Steel Fastener Grades

Duplex steel fasteners are available in 3 standard grade designations. Each grade is selected based on corrosion resistance, mechanical load, and applicable project specifications.

• Duplex Steel 2205 Fasteners
• Duplex Steel UNS S32205 Fasteners
• Duplex Steel UNS S31803 Fasteners

Types of Duplex Steel Fasteners

Duplex fasteners are produced in 4 standard categories, covering the full range of tensile, compressive, and sealing requirements across industrial piping and structural applications.

• Lean Duplex Fasteners
• Standard Duplex Fasteners
• Super Duplex Fasteners
• Hyper Duplex Fasteners

Duplex Steel Fasteners Specifications

The table below covers the complete technical specifications for duplex stainless steel fasteners, including material grades, applicable standards, size ranges, and service conditions.

Duplex Steel Fasteners Size Chart

The size chart below maps each fastener type to its metric and imperial range for quick selection across standard project requirements.

Duplex Fastener Dimensions

The dimension table below lists nominal diameters alongside thread form and length range for standard duplex stainless steel fasteners used in engineering applications.

Schedule Chart Of Duplex Steel Fasteners

The schedule chart below maps each nominal size to its standard thread pitch, length range, and common fastener form for duplex steel fasteners used in industrial and structural projects.

Key Features Of Duplex Steel Fasteners

Duplex steel fasteners have 7 key features that set them apart from standard austenitic stainless steel fasteners in demanding service environments.

• High Strength
• Excellent Corrosion Resistance
• Good Toughness
• Reduced Thermal Expansion
• Enhanced Fatigue Resistance
• Cost-Effectiveness
• Ease of Fabrication

Applications Of Duplex Steel Fasteners

Duplex fasteners are specified across 9 industries where corrosion control, mechanical load, and long service life cannot be compromised.

• Oil and Gas Industry
• Chemical Processing
• Marine and Offshore Structures
• Power Generation
• Pulp and Paper Industry
• Water Treatment Plants
• Construction and Infrastructure
• Food and Beverage Processing
• Automotive and Aerospace

How to choose the right duplex steel fasteners supplier and manufacturer

Choosing the right duplex fastener manufacturer has a direct impact on documentation quality, delivery schedules, and overall procurement costs. Before placing an order, evaluate each supplier in four areas.

Selecting the right supplier and manufacturer

Avoid general fastener distributors. Search for duplex stainless steel fastener specialists who maintain ready stock, provide certified mill test reports (MTRs), and operate under ISO 9001 quality management standards.

Technical considerations

Verify that the supplier has the proper grade (UNS S31803 or UNS S32205), size range, thread form, and fastener standard (DIN 934, DIN 931, or ASTM A182). When ordering for offshore or sour service applications, request NACE MR0175 / ISO 15156 compliance documentation.

Evaluating supplier credibility

Quality control should be verified through certifications such as IBR, PED, and Lloyd’s Register. Always request these documents before placing an order. A reliable duplex steel fastener supplier should also provide lot-wise dimensional inspection reports, hardness test results, and chemical composition certificates for every batch.

Procurement strategy

When ordering in bulk or for projects, look for a manufacturer of duplex fasteners who maintains flexible order volume terms, delivery dates, and transparent pricing. Request for hydrostatic test reports, dimensional inspection types & packing information before dispatch. Check stock and lead times before placing an order and avoid delays.