Table of Contents
- SS 347/347H Nuts Overview
- SS 347/347H Nuts Specifications
- What are Stainless Steel 347/347H Nuts?
- SS 347 / 347H Technical Properties & Composition
- Why Industries Prefer SS 347 Series Nuts
- Types of SS 347 Series Nuts
- Key Advantages of UNS S34700 / S34709 Series Nuts
- Key Applications of SS UNS S34700 Series Nuts
- SS 347 Nuts vs SS 321 Nuts
- Quality Testing & Inspection
- Global Export Markets
- Frequently Asked Questions
- Contact Aurum Overseas
SS 347 / 347H (ASTM A193 B8C) Nuts Supplier & Exporter
Aurum Overseas is an established, precision-focused SS 347/347H Nuts Supplier and specialized SS 347/347H Nuts Exporter. As a premier ASTM A193 B8C Nuts Supplier and trusted ASTM A193 B8C Nuts Exporter, we stock and manufacture columbium (niobium) stabilized austenitic stainless steel fasteners designed specifically for heavy-duty, elevated-temperature service in the 427°C to 870°C (800°F to 1600°F) range.
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Manufactured under strict ASTM A193 B8C Class 1 and Class 2 standards, these high-temperature fasteners prevent heat damage and corrosion during welding and extreme thermal service. As a global SS 347/347H Nuts Exporter and ASTM A193 B8C Nuts Exporter, Aurum Overseas supplies fully certified bolting across the USA, Germany, UK, UAE, Saudi Arabia, and Qatar.
SS 347/347H Nuts Specifications
| Parameter | Specification / Technical Range |
|---|---|
| Material Grades | SS 347, SS 347H |
| UNS Numbers | UNS S34700 / UNS S34709 |
| Manufacturing Standards | ASTM A193 / ASME SA193 Grade B8C (Class 1 & Class 2), ASTM A320 Grade B8C, DIN, ISO, BS |
| Size Range | M3 to M160 | 3/16" to 2-1/2" | Custom Sizes Available |
| Length Range | 3 mm to 200 mm | Custom Lengths Available |
| Thread Configuration | ASME B1.1 2A/3A - 2B/3B Unified (UNC, UNF, UNEF) & B1.13M 6h-6G Metric Coarse/Fine |
| Special Fastener Formats | SS 347 Hex Head Nuts, SS 347 Square Nuts, SS 347 T Nuts, SS 347 Eye Nuts |
| Classes Available | Class 1 (Carbide Solution Treated) & Class 2 (Strain Hardened) |
| 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 347/347H Nuts?
Type 347 (UNS S34700 / 1.4550) and Type 347H (UNS S34709 / 1.4961) are columbium-stabilized austenitic stainless steels engineered for high-temperature structural bolting where maximum resistance to intergranular attack and stress rupture is required.
- SS 347 (UNS S34700 / 1.4550): The standard grade made with added niobium (columbium) to lock in carbon, preventing heat damage and rusting during heavy welding or high-temperature use.
- SS 347H (UNS S34709 / 1.4961): The high-carbon version engineered specifically to hold heavy loads without stretching or weakening in continuous heat above 537°C (1000°F).
SS 347 / 347H Technical Properties & Composition
The chemical composition and mechanical properties of the 347 series are precisely engineered to deliver niobium-stabilized protection against intergranular corrosion, superior creep resistance, and dependable fastener integrity under extreme thermal and mechanical service conditions.
Chemical Composition of ASTM A193 Grade B8C Fasteners (%)
| Element | Percentage |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.00 - 19.00 |
| Nickel (Ni) | 9.00 - 13.00 |
| Columbium + Tantalum (Cb+Ta) | 10 x Carbon min - 1.10 max |
Mechanical Properties of ASTM A193 Grade B8C Fasteners
| Grade / Class | Diameter | Tensile Strength (min) | Yield Strength (min) |
|---|---|---|---|
| Grade B8C, Class 1 | All Diameters | 515 MPa | 205 MPa |
| Grade B8C, Class 2 | M20 and under | 860 MPa | 690 MPa |
| Grade B8C, Class 2 | M20 to M24 | 690 MPa | 550 MPa |
| Grade B8C, Class 2 | M24 to M30 | 655 MPa | 450 MPa |
| Grade B8C, Class 2 | M30 to M36 | 620 MPa | 345 MPa |
Equivalent Grades of SS 347 / 347H Nuts
| Grade | ASTM | EN / DIN Equivalent | UNS Designation | JIS Equivalent | EN / DIN Equivalent |
|---|---|---|---|---|---|
| SS 347 | A193 B8C, A320 B8C | EN 1.4550 | UNS S34700 | SUS347 | X6CrNiNb18-10 |
| SS 347H | — | EN 1.4961 | UNS S34709 | SUS347H | X6CrNiNb18-12 |
Why Industries Prefer SS 347 Series Nuts
Engineers specify SS 347 and 347H nuts for high-temperature environments (427°C to 870°C) where standard stainless steel loses structural strength.
By adding columbium (niobium), SS 347 series nuts lock in key elements to prevent heat damage, intergranular cracking, and weld decay. As a certified SS 347/347H Nuts Supplier and ASTM A193 B8C Nuts Supplier, Aurum Overseas delivers these durable fasteners to power plants, refineries, and exhaust system manufacturers worldwide.
Types of SS 347 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 347 Hex Head Nuts
SS 347 Square Nuts
SS 347 Lock Nuts
SS 347 Eye Nuts
SS 347 Wing Nuts
SS 347 T Nuts
SS 347 Panel Nuts
SS 347 Coupling Nuts
SS 347 Dome Nuts
Key Advantages of UNS S34700 / S34709 Series Nuts
Built-In Heat Protection
Columbium (niobium) locking prevents heat-related weakness and keeps the nuts strong in temperatures up to 870°C (1600°F).
Extra Strength for High Temps (347H)
The higher carbon content in 347H 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 ASTM A193 Grade B8C Nuts
Our stainless steel 347 and 347H nuts are deployed globally in high-temperature refining operations, power generation systems, aerospace, and critical chemical processing assemblies.
| Industry Sector | Primary Fastener Application |
|---|---|
| Refining & Petrochemical | Catalytic cracking units (FCCU), fluid coking equipment, and high-temperature hydrotreater bolting |
| Power Generation | Steam turbine casing joints, superheater tube supports, and heavy boiler ductwork bolting |
| Aerospace & Defence | Aircraft collector rings, jet engine manifold fasteners, and high-temperature exhaust stack connections |
| Chemical Processing | High-temperature organic synthesis reactors, waste heat boilers, and nitric acid system joints |
| Oil & Gas Heavy Utilities | High-pressure piping flanges subjected to cyclic thermal stress and sour gas exposure |
SS 347 Nuts vs SS 321 Nuts
When selecting the ideal niobium-stabilized or titanium-stabilized stainless fastener grade, understanding the performance differences between SS 347 and SS 321 is essential.
| Comparison Factor | SS 347 / 347H Nuts | SS 321 / 321H Nuts |
|---|---|---|
| Additive Element | Uses Niobium (Columbium) to prevent heat damage | Uses Titanium to prevent heat damage |
| Heat Resistance Range | Handles slightly higher heat up to 870°C (1600°F) | Performs reliably up to 816°C (1500°F) |
| Welding Performance | Superior for heavy welding because niobium stays intact in the weld area | Great for general use, but titanium can burn off during heavy welding |
| Strength at High Temps | Stronger under long-term heavy stress at extreme temperatures | Strong and durable for most high-heat jobs |
| Cost & Availability | Premium choice, usually reserved for extreme welding jobs | More common and cost-effective |
| Detailed Specifications | Current Page | View SS 321 Nuts Specs → |
Quality Testing & Inspection
Aurum Overseas implements rigorous quality assurance practices to guarantee every shipment supplied by our team as an SS 347/347H Nuts Supplier and ASTM A193 B8C Nuts Supplier meets project technical requirements.
| Test / Inspection Standard | Technical Verification Scope |
|---|---|
| Positive Material Identification (PMI) | Spectroscopic alloy verification confirming Cb+Ta, 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 Class 2 and standard Class 1 properties |
| Intergranular Corrosion (IGC) | Testing per ASTM A262 Practice E to verify complete immunity 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 347/347H Nuts Exporter and ASTM A193 B8C 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 A193 Grade B8C specifies niobium (columbium) stabilized SS 347 nuts. The niobium addition prevents intergranular corrosion when fasteners operate continuously within the heat range of 427°C to 870°C, especially after heavy welding.
Class 1 B8C nuts are carbide solution treated for maximum corrosion resistance and standard yield strength (205 MPa). Class 2 B8C nuts are strain-hardened during production to achieve significantly higher tensile strength (up to 860 MPa).
SS 347 is the standard niobium-stabilized grade with 0.08% max carbon. SS 347H features a controlled carbon range (0.04% to 0.10%), providing superior creep and stress-rupture strength for continuous service above 537°C.
Aurum Overseas manufactures and exports a full line including SS 347 Hex Head Nuts, SS 347 Square Nuts, SS 347 T Nuts, and heavy forged SS 347 Eye Nuts tailored to client specifications.
Yes, Aurum Overseas regularly exports certified SS 347/347H and ASTM A193 B8C fasteners to major industrial projects across the USA, European markets (Germany, UK, France, Netherlands), and Gulf GCC nations (UAE, Saudi Arabia, Qatar, Oman, Kuwait, Bahrain).
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.