Table of Contents
- SS 321/321H Nuts Overview
- SS 321/321H Nuts Specifications
- What are Stainless Steel 321/321H Nuts?
- SS 321 / 321H Technical Properties & Composition
- Why Industries Prefer SS 321 Series Nuts
- Types of SS 321 Series Nuts
- Key Advantages of UNS S32100 / S32109 Series Nuts
- Key Applications of SS UNS S32100 Series Nuts
- SS 321 Nuts vs SS 347 Nuts
- Quality Testing & Inspection
- Global Export Markets
- Frequently Asked Questions
- Contact Aurum Overseas
SS 321 / 321H Nuts Suppliers & Exporters
Aurum Overseas is an established, precision-driven SS 321/321H Nuts Supplier and specialized SS 321/321H Nuts Exporter. Titanium-stabilized against chromium carbide precipitation, Type 321 and high-carbon Type 321H fasteners are engineered specifically for high-temperature service within the carbide precipitation thermal window of 427°C to 816°C (800°F to 1500°F).
Manufactured under strict ASTM A194 Gr 8T and ASTM A193 standards, these titanium-stabilized fasteners maintain long-term strength, joint integrity, and corrosion resistance in high-temperature processing units. As a trusted SS 321/321H Nuts Exporter, Aurum Overseas supplies fully certified bolting across the USA, Canada, Mexico, Germany, UK, France, Italy, Netherlands, Belgium, Spain, Poland, UAE, Saudi Arabia, Qatar, Kuwait, Oman, and Bahrain.
SS 321/321H Nuts Specifications
| Parameter | Specification / Technical Range |
|---|---|
| Material Grades | SS 321, SS 321H |
| UNS Numbers | UNS S32100 / UNS S32109 |
| Werkstoff Numbers | 1.4541 (321) / 1.4878 (321H) |
| Manufacturing Standards | ASTM A194 Gr 8T Nuts, ASTM A193 / ASME SA193, IS, BS, DIN 934, ISO 4032 |
| Size & Length Range | 3 mm to 200 mm (Size) | M02 to M33 (Length) | Custom heavy hex formats |
| Thread Configuration | ASME B1.1 2A/3A - 2B/3B Unified (UNC, UNF, UNEF) & B1.13M 6h-6G Metric Coarse/Fine |
| Special Fastener Formats | SS 321 Hex Head Nuts, SS 321 Square Nuts, SS 321 T Nuts, SS 321 Eye Nuts |
| Surface Finishes | Bright Polished, Passivated, Solution Annealed, Hot-Dip Galvanized, Electro-polished |
| Certifications | EN 10204 3.1 Material Test Certificate, NACE MR0175 / ISO 15156 Compliant |
What are Stainless Steel 321/321H Nuts?
Type 321 (UNS S32100) and Type 321H (UNS S32109) are titanium-stabilized austenitic stainless steels engineered for elevated-temperature structural bolting where intergranular corrosion resistance is paramount.
- SS 321 (UNS S32100 / 1.4541): Standard titanium-stabilized grade formulated with a minimum titanium addition of 5×(C+N) to tie up carbon atoms and eliminate intercrystalline decay.
- SS 321H (UNS S32109 / 1.4878): High-carbon variant (0.04% to 0.10% C) heat-treated for higher creep and stress-rupture strength at operating temperatures above 537°C (1000°F).
SS 321 / 321H Technical Properties & Composition
The chemical composition and mechanical properties of the 321 series are carefully engineered to deliver titanium-stabilized protection against intergranular corrosion, outstanding creep resistance, and reliable fastener performance across extreme thermal cycling environments.
Chemical Composition of UNS S32100 / S32109 Nuts (%)
| Element | SS 321 (Min / Max) | SS 321H (Min / Max) |
|---|---|---|
| Carbon (C) | — / 0.08 | 0.04 / 0.10 |
| Manganese (Mn) | — / 2.00 | — / 2.00 |
| Silicon (Si) | — / 0.75 | — / 0.75 |
| Phosphorus (P) | — / 0.045 | — / 0.045 |
| Sulfur (S) | — / 0.030 | — / 0.030 |
| Chromium (Cr) | 17.0 / 19.0 | 17.0 / 19.0 |
| Molybdenum (Mo) | — | — |
| Nickel (Ni) | 9.0 / 12.0 | 9.0 / 12.0 |
| Nitrogen (N) | — / 0.10 | — |
| Titanium (Other) | Ti = 5×(C+N) / 0.70 | Ti = 4×(C+N) / 0.70 |
Mechanical Properties of SS 321 / 321H Nuts
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness Rockwell B (HR B) max | Hardness Brinell (HB) max |
|---|---|---|---|---|---|
| SS 321 | 515 | 205 | 40 | 95 | 217 |
| SS 321H | 515 | 205 | 40 | 95 | 217 |
Equivalent Grades of SS 321 / 321H Nuts
| Grade | UNS | W.Nr. | JIS | EN |
|---|---|---|---|---|
| SS 321 | S32100 | 1.4541 | SUS 321 | X6CrNiTi18-10 |
| SS 321H | S32109 | 1.4878 | SUS 321H | X6CrNiTiB18-10 |
Why Industries Prefer SS 321 Series Nuts
Engineers choose SS 321 and 321H nuts primarily for high-heat environments where standard stainless steel fasteners lose strength and degrade. When regular stainless steel is exposed to temperatures between 427°C and 816°C, its internal structure becomes vulnerable to heat damage and cracking.
By adding titanium to the metal mix, SS 321 series nuts create a protective shield that locks in key elements, keeping the fastener strong, rust-resistant, and stable even under extreme thermal cycling. As a reliable SS 321/321H Nuts Supplier, Aurum Overseas supplies these durable, high-heat nuts to power plants, oil refineries, and exhaust system manufacturers worldwide.
Types of SS 321 Series Nuts
Aurum Overseas supplies a comprehensive range of stainless steel nut configurations manufactured according to standard DIN, ASME, and ISO dimensional tolerances for multiple engineering assemblies.
SS 321 Hex Head Nuts
SS 321 Square Nuts
SS 321 Lock Nuts
SS 321 Eye Nuts
SS 321 Wing Nuts
SS 321 T Nuts
SS 321 Panel Nuts
SS 321 Coupling Nuts
SS 321 Dome Nuts
Key Advantages of UNS S32100 / S32109 Series Nuts
Built-In Heat Protection
Titanium locking prevents heat-related weakness and keeps the nuts strong in temperatures up to 816°C (1500°F).
Extra Strength for High Temps (321H)
The higher carbon content in 321H keeps the nut from stretching, sagging, or weakening under continuous heavy loads at high heat.
Handles Thermal Shock
Easily copes with quick, repeated temperature swings from freezing cold to scorching hot without cracking or bending.
High Flexibility & Toughness
Stretches under heavy pressure without snapping, ensuring tight and secure threads even under high vibration.
Resists Harsh Gas Exposure
Protects against cracking and surface breakdown in hot gas lines, exhaust manifolds, and refinery processing units.
Key Applications of SS UNS S32100 Series Nuts
Our stainless steel 321 and 321H nuts are deployed globally in high-temperature refining operations, power generation systems, and aerospace thermal management assemblies.
| Industry Sector | Primary Fastener Application |
|---|---|
| Refining & Petrochemical | Thermal catalytic cracking units (FCCU), hydrotreaters, and flare stack bolting |
| Power Generation | Superheater tube supports, steam header flanges, and boiler casing fasteners |
| Aerospace & Rocketry | Jet engine exhaust manifolds, piston engine collectors, and heat exchanger joints |
| Chemical Processing | High-temperature organic chemical reactors and waste heat recovery units |
| Thermal Treatment | Furnace hardware, incinerator flanges, and thermal oxidizer structural joints |
SS 321 Nuts vs SS 347 Nuts
When selecting the ideal titanium-stabilized or niobium-stabilized stainless fastener grade, understanding the performance differences between SS 321 and SS 347 is essential.
| Comparison Factor | SS 321 / 321H Nuts | SS 347 / 347H Nuts |
|---|---|---|
| Additive Element | Uses Titanium to prevent heat damage | Uses Niobium (Columbium) to prevent heat damage |
| Heat Resistance Range | Performs reliably up to 816°C (1500°F) | Handles slightly higher heat up to 870°C (1600°F) |
| Welding Performance | Great for general use, but titanium can burn off during heavy welding | Superior for heavy welding because niobium stays intact in the weld area |
| Strength at High Temps | Strong and durable for most high-heat jobs | Stronger under long-term heavy stress at extreme temperatures |
| Cost & Availability | More common and cost-effective | Premium choice, usually reserved for extreme welding jobs |
| Detailed Specifications | Current Page | View SS 347 Nuts Specs → |
Quality Testing & Inspection
Aurum Overseas implements rigorous quality assurance practices to guarantee every shipment supplied by our team as an SS 321/321H Nuts Supplier meets project technical requirements.
| Test / Inspection Standard | Technical Verification Scope |
|---|---|
| Positive Material Identification (PMI) | Spectroscopic alloy verification confirming Ti, Cr, Ni, and Fe levels |
| Dimensional & Thread Gaging | Thread pitch, concentricity, and lead verification per ASME B18.2.2 and DIN standards |
| Proof Load & Tensile Testing | Mechanical verification of strain-hardened and standard strength properties |
| Intergranular Corrosion (IGC) | Testing per ASTM A262 Practice E to verify resistance to intercrystalline attack |
| Certified Mill Traceability | EN 10204 3.1 Certification accompanying all heat-treated manufacturing lots |
Global Export Markets
As a globally recognized SS 321/321H Nuts Exporter, Aurum Overseas ships fully tested, seaworthy-packaged high-temperature fasteners to industrial buyers worldwide.
USA
Canada
Mexico
Germany
United Kingdom
France
Italy
Netherlands
Belgium
Spain
Poland
UAE
Saudi Arabia
Qatar
Kuwait
Oman
Bahrain
Frequently Asked Questions
ASTM A194 Gr 8T specifies titanium-stabilized SS 321 nuts. The titanium addition prevents intergranular corrosion when fasteners operate continuously within the carbide precipitation range of 427°C to 816°C.
SS 321 is the standard titanium-stabilized grade with a carbon limit of 0.08% max. SS 321H features a controlled higher carbon content (0.04% to 0.10%), providing elevated creep and stress-rupture strength for operating temperatures above 537°C.
While both are stabilized stainless steels, SS 321 uses titanium, whereas SS 347 uses niobium. SS 321 is typically the more economical and widely available option for general high-temperature service up to 816°C.
Aurum Overseas manufactures and exports a full line including SS 321 Hex Head Nuts, SS 321 Square Nuts, SS 321 T Nuts, and heavy forged SS 321 Eye Nuts per customer specifications.
Yes, every shipment from Aurum Overseas includes complete EN 10204 3.1 Mill Test Certificates detailing chemical analysis (including titanium ratios), hardness results, proof load testing, and heat batch traceability.
Yes, Aurum Overseas regularly exports certified SS 321 and 321H fasteners to major energy hubs across the USA, European markets (Germany, UK, France, Netherlands), and Gulf GCC nations (UAE, Saudi Arabia, Qatar, Oman, Kuwait, Bahrain).
We offer expedited air freight and scheduled sea freight shipping options to North America and European ports, ensuring secure export-grade palletized packaging for safe transit.
Contact Aurum Overseas
Aurum Overseas provides rapid quoting, complete technical documentation, and reliable export logistics for all your stainless steel bolting demands.
Contact our sales team to request a quote or confirm specification compliance.