Stainless Steel 347H Fasteners are high-carbon, niobium-stabilized fasteners made from UNS S34709 stainless steel. They are primarily selected for high-temperature applications requiring resistance to oxidation, corrosion and intergranular attack.
Stainless Steel 347H Fasteners – UNS S34709 Bolts, Nuts & Studs
Stainless Steel 347H Fasteners are high-carbon, niobium-stabilized austenitic stainless steel fasteners designed for elevated-temperature service. Identified by UNS S34709, Werkstoff No. 1.4961, JIS SUS 347H, and EN X6CrNiNb18-12, they offer good oxidation resistance, corrosion resistance, and creep strength at high temperatures. Their stabilized structure helps reduce chromium carbide precipitation during prolonged heating, making SS 347H Fasteners suitable for heat exchangers, boilers, steam systems, petrochemical equipment, power-generation systems, and waste heat recovery units.
We supply 347H Stainless Steel Bolts and Nuts, stud bolts, threaded rods, hex bolts, screws, washers and custom fasteners in different dimensions, thread forms and finishes according to project requirements.
What is Stainless Steel 347H?
SS 347H is the higher-carbon version of Type 347 stainless steel. The addition of niobium provides stabilization against sensitization, while the higher carbon content supports improved high-temperature strength compared with standard 347 in suitable service conditions.
The grade is particularly useful where fasteners remain exposed to elevated temperatures for extended periods. This makes High Carbon 347H Fasteners a practical choice for demanding industrial assemblies where both mechanical integrity and corrosion resistance are important.
Table of Contents
- ➤ What is Stainless Steel 347H?
- ➤ Key Features and Benefits of 347H Stainless Steel Fasteners
- ➤ Types of SS 347H Fasteners We Supply
- ➤ Stainless Steel 347H Fasteners Specifications
- ➤ Chemical Composition of 347H Stainless Steel
- ➤ Mechanical Properties of 347H Fasteners
- ➤ 347H Stainless Steel Equivalent Grades
- ➤ Manufacturing Process of SS 347H Fasteners
- ➤ Applications of JIS SUS 347H Fasteners
- ➤ Why Choose Us for ASME SA193 347H Studs?
Key Features and Benefits of 347H Stainless Steel Fasteners
- High-temperature strength: Higher carbon content provides improved creep and stress-rupture performance compared with standard 347.
- Niobium stabilization: Niobium helps stabilize carbon and reduces susceptibility to intergranular corrosion after elevated-temperature exposure.
- Excellent thermal stability: Suitable for prolonged high-temperature applications.
- Good corrosion resistance: Provides the corrosion resistance expected from an austenitic Cr-Ni stainless steel.
- Strong joint integrity: Suitable for pressure, piping and equipment connections operating under demanding thermal conditions.
- Good oxidation resistance: Useful in furnace, heat-recovery and power-generation environments.
- Wide product availability: Available as bolts, nuts, studs, screws, threaded rods and specialty fasteners.
- International specifications: Can be manufactured and supplied to applicable ASTM, ASME, DIN, EN and JIS requirements.
Types of SS 347H Fasteners We Supply
We manufacture and supply a wide range of SS 347H Fasteners for industrial and engineering applications:
- UNS S34709 Stud Bolts
- UNS S34709 Hex Bolts
- Stainless Steel 347H Hex Head Bolts
- 347H Stainless Steel Heavy Hex Bolts
- 347H Stainless Steel Nuts
- Heavy Hex Nuts
- AISI 347H Screws
- 347H Threaded Rods
- Double-End Studs
- Full Thread Stud Bolts
- Machine Screws
- Washers
- Custom-designed 347H Fasteners
- High-temperature flange fasteners
Fasteners can be supplied in standard or customized dimensions, thread configurations and finishes according to customer drawings and applicable standards.
Stainless Steel 347H Fasteners Specifications
| Specification | Details |
|---|---|
| Product | Stainless Steel 347H Fasteners |
| Grade | 347H |
| UNS | S34709 |
| AISI | 347H |
| EN/DIN Material No. | 1.4961 |
| EN Designation | X6CrNiNb18-12 |
| JIS | SUS 347H |
| Material Type | Niobium-stabilized austenitic stainless steel |
| Product Forms | Bolts, nuts, studs, screws, threaded rods, washers |
| Threads | UNC, UNF, metric and special threads |
| Manufacturing | Cold forged, hot forged, machined as applicable |
| Inspection | Dimensional, visual, PMI and mechanical testing as specified |
| Certification | MTC / EN 10204 3.1 or 3.2 when required |
Note: Exact dimensional and material requirements depend on the selected product standard, diameter, class and application.
Chemical Composition of 347H Stainless Steel
| Element | Typical / Specified Range (%) |
|---|---|
| Carbon (C) | 0.04–0.10 |
| Chromium (Cr) | 17.0–19.0 |
| Nickel (Ni) | 9.0–13.0 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Niobium (Nb) | Stabilizing addition |
Mechanical Properties of 347H Fasteners
| Property | Typical Minimum |
|---|---|
| Tensile Strength | 515 MPa |
| Yield Strength | 205 MPa |
| Elongation | 40% |
| Hardness | Grade/specification dependent |
For pressure-retaining or critical bolting, the applicable ASTM/ASME product specification should take precedence over generic material-property values.
347H Stainless Steel Equivalent Grades
| Standard / System | Equivalent / Designation |
|---|---|
| UNS | S34709 |
| AISI | 347H |
| EN / DIN | 1.4961 |
| EN Symbolic | X6CrNiNb18-12 |
| JIS | SUS 347H |
| ASTM / ASME | Application-specific 347H product specifications |
Important: Material equivalents are not automatically interchangeable for every fastener application. The mechanical, dimensional, heat-treatment and certification requirements of the governing fastener standard must be checked before substitution.
Manufacturing Process of SS 347H Fasteners
Applications of JIS SUS 347H Fasteners
Waste Heat Recovery Grade 347H SS Fasteners are particularly suitable for high-temperature equipment and connections where standard stainless steel fasteners may not provide sufficient long-term creep performance.
Typical applications include:
- Waste heat recovery systems
- Power generation plants
- Steam piping and headers
- Heat exchangers
- Superheaters and reheaters
- Petrochemical processing equipment
- Oil and gas processing facilities
- Refinery furnace equipment
- Chemical processing plants
- High-temperature pressure vessels
- Gas and steam turbine systems
- Furnace and thermal-processing equipment
- High-temperature flanged pipe connections
347H is recognized for elevated-temperature service in applications such as steam piping, furnace components, catalytic processing equipment and power-generation systems.
Why Choose Us for ASME SA193 347H Studs?
We supply Stainless Steel 347H Fasteners for domestic and international industrial requirements with an emphasis on material traceability, dimensional accuracy and specification compliance.
What you can expect:- 40+ years of experience in metal products and industrial supply
- Wide range of stainless steel and specialty alloy products
- Material traceability through heat numbers and MTCs
- Inspection and testing as specified
- Support for third-party inspection requirements
- Customized sizes and fastener configurations
- Export-oriented packaging and documentation
- Competitive quotations for project and bulk requirements
- Support for EPC, engineering and industrial procurement requirements
Whether you require UNS S34709 Stud Bolts, DIN 1.4961 Bolts, AISI 347H Screws, JIS SUS 347H Fasteners or customized niobium-stabilized SS 347H bolts, we can assist with material selection and documentation based on your project specification.
Related Stainless Steel Fasteners
We also supply:
- Stainless Steel 304 fasteners
- Stainless Steel 304l Fasteners
- Stainless Steel 304H Fasteners
- Stainless Steel 309 Fasteners
- Stainless Steel 309S Fasteners
- Stainless Steel 309H Fasteners
- Stainless Steel 310 Fasteners
- Stainless Steel 310S Fasteners
- Stainless Steel 310H Fasteners
- Stainless Steel 316 Fasteners
- Stainless Steel 316L Fasteners
- Stainless Steel 316H Fasteners
- Stainless Steel 316TI Fasteners
- Stainless Steel 317 Fasteners
- Stainless Steel 317L Fasteners
- Stainless Steel 321 Fasteners
- Stainless Steel 321H Fasteners
- Stainless Steel 347 Fasteners
- Stainless Steel 347H Fasteners
- Stainless Steel 410 Fasteners
- Stainless Steel 446 Fasteners
- Stainless Steel 904L Fasteners
Request a Quote for 347H Stainless Steel Fasteners
Need high-temperature 347H Stainless Steel Fasteners for a refinery, power plant, waste heat recovery system, heat exchanger or piping project?
Send us your size, quantity, fastener type, applicable standard, thread requirement, material certification requirement and delivery location. We can review your specification and provide a quotation for UNS S34709 bolts, nuts, studs, screws and customized fasteners.
Frequently Asked Questions
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