Description
Quick answer
Duplex 2205 stud bolts combine higher strength than common austenitic stainless steels with useful resistance to chloride stress-corrosion cracking. Specify UNS S31803 or the tighter-composition UNS S32205 explicitly, together with the required bar condition, fastener properties, thread, nut material and inspection documentation.
Product specifications
| Material designation | Duplex stainless steel 2205; UNS S31803 or UNS S32205; EN 1.4462 |
|---|---|
| Material / bar reference | ASTM A276 or ASTM A479 when the ordered product form, UNS grade and condition are covered |
| Finished fastener reference | ASTM F593 or project fastener specification where the selected UNS, condition and size are within scope |
| Stud configuration | Fully threaded stud bolts; custom double-end details by approved drawing |
| Inch threads | UNC, UNF and 8UN to ASME B1.1 as specified |
| Metric threads | Coarse or fine metric threads to ASME B1.13M / ISO requirements as specified |
| Dimensions | Diameter and length to flange bolting schedule, ASME B18.31.2 reference or approved drawing |
| Matching nuts | Compatible heavy hex or project-design nuts supplied after material and property review |
| Documentation | EN 10204 3.1 MTC, heat traceability and dimensional report; PMI/NDT/testing optional |
Why specify Duplex 2205 stud bolts?
2205 is a practical first-choice duplex grade for process piping and moderate chloride exposure when 316L does not provide sufficient localized-corrosion margin. Its duplex ferritic-austenitic microstructure makes heat treatment and manufacturing control important: material identity, solution-annealed condition and phase balance should not be inferred from appearance.
Corrosion resistance and material limits
The grade offers good resistance to uniform corrosion, pitting, crevice corrosion and chloride stress-corrosion cracking in many industrial environments. Actual performance depends on chloride level, temperature, pH, oxidizing potential, deposits and joint geometry. It is not a universal replacement for every nickel alloy or super duplex grade.
Engineering note: Material selection must be based on the complete process environment and governing design code. Product-page information is not a design allowable or a guarantee of service life.
Temperature and mechanical-property control
Duplex 2205 is primarily selected for corrosion resistance and strength rather than prolonged high-temperature bolting. Minimum and maximum design temperature, impact testing and any sour-service restrictions must come from the piping class and governing code.
Typical applications
- Offshore process skids and seawater utility piping
- Chemical processing flanges, pumps and valves
- Pulp and paper digesters and process equipment
- Desalination and water-treatment systems
- Marine structural and heat-exchanger connections
Standards, threads and flange fit-up
The material specification controls alloy chemistry, product form, heat treatment and mechanical tests. The finished-fastener specification controls stud manufacture and acceptance. The flange standard or bolting schedule controls diameter, thread and length. These documents perform different jobs and should all be identified at order review.
Cut threads and rolled threads can produce different dimensional, surface and residual-stress characteristics. State the required manufacturing method when it is a design requirement. Thread fit, end chamfers, nut engagement and exposed thread allowance must match the assembly procedure.
Matching nuts, lubrication and galling control
High-alloy studs should be purchased as part of an engineered bolting system. Nut material and proof strength must support the specified stud properties without creating an unacceptable corrosion couple. Clean threads, controlled surface finish and an approved lubricant reduce galling and torque scatter.
Torque values are not universal. Friction coefficient, coating or lubricant, nut condition, tightening sequence and reuse policy all affect achieved preload. Use a project-approved torque-tension or hydraulic-tensioning procedure.
Manufacturing, inspection and documentation
Production can include material verification, sawing, end preparation, thread machining or rolling, cleaning, dimensional inspection and permanent identification. Heat numbers remain traceable through manufacturing. Additional controls can include PMI, hardness, tensile tests, impact tests, microstructure examination, corrosion testing, ultrasonic testing or dye penetrant testing when specified.
Inspection documents should identify the ordered UNS grade, material specification and condition—not only a trade name. Third-party inspection, EN 10204 3.2 certification and customer hold points can be incorporated before production when agreed.
What to include in your RFQ
State whether S31803 or S32205 is mandatory. Include any ferrite/phase-balance requirement, corrosion testing such as ASTM G48 when contractually required, PMI scope, impact-test temperature and restrictions on repair or marking.
- Exact UNS designation and governing material specification/edition
- Finished-fastener and dimensional standard
- Diameter, thread series, pitch and overall length
- Required material condition and mechanical properties
- Nut and washer material, dimensions and quantity
- Design temperature, process environment and special service standard
- Testing, inspection, traceability and certificate type
- Lubrication, coating, marking, packing and delivery requirements
Authoritative material reference
Review Outokumpu Forta duplex stainless steel data together with the contractually required ASTM/ASME/ISO editions. Manufacturer literature supports material screening; the purchase order and governing code control supply.
Related stud bolt materials
Frequently asked questions
Are UNS S31803 and S32205 identical?
They are closely related 2205 designations, but S32205 has tighter chemistry limits intended to support consistent corrosion performance. Order the exact UNS required by the project.
Can Duplex 2205 stud bolts be used with 316 stainless nuts?
Nut selection must be engineered as a bolting system. A different alloy may change strength, galvanic behavior and galling risk, so use the specified compatible nut grade and lubrication procedure.
Can you supply ASTM G48 testing?
Testing can be arranged when the purchase order defines the method, temperature, acceptance criterion, sampling and reporting requirements.
What documentation is available?
Typical documentation includes EN 10204 3.1 material certificates, heat traceability, dimensional inspection and optional PMI or additional testing agreed at order review.
Trade names are used for material identification. INCONEL®, INCOLOY® and MONEL® are trademarks of Special Metals Corporation; HASTELLOY® is a trademark of Haynes International, Inc. SASA FLANGE supplies products to the specifications stated on the accepted order.
