Table of Contents
- SS 347/347H Washers Overview
- SS 347/347H Washers Specifications
- SS 347 Series Technical Properties & Composition
- SS 347 vs. SS 347H
- Why Industries Prefer SS 347/347H Washers
- Types of SS 347 Washers
- Key Technical Advantages
- Key Applications of SS 347/347H Washers
- Quality Testing & Inspection
- Global Export Markets
- Frequently Asked Questions
- Contact Aurum Overseas
SS 347/347H Washers Suppliers & Exporters
Aurum Overseas is a trusted SS 347/347H Washers Supplier and SS 347/347H Washers Exporter, offering high-quality niobium-stabilized stainless steel washers built for high-temperature and thermal cycling environments.
Manufactured to ASME B18.21.1, DIN 125, and ISO 7089 standards, our UNS S34700 / S34709 Washers feature columbium (niobium) stabilization to prevent intergranular corrosion and material breakdown at continuous operating temperatures from 425°C to 816°C (800°F to 1500°F).
As a leading SS 347/347H Washers Exporter, Aurum Overseas supplies fully certified washers with fast shipping to clients across North America, Europe, the Middle East, and the Asia-Pacific region.
SS 347/347H Washers Specifications
| Parameter | Technical Specification / Standard Range |
|---|---|
| Material Grades | Stainless Steel 347 (UNS S34700) / 347H (UNS S34709) |
| UNS Designations | UNS S34700 / S34709 Washers |
| Werkstoff Numbers | 1.4550 (347) / 1.4912 (347H) |
| Manufacturing Standards | ASTM A240 / ASME SA240, ASTM A193/A194 Hardware Specs |
| Dimensional Specifications | ASME B18.21.1, DIN 125 A/B, DIN 127 B, DIN 9021, ISO 7089, ISO 7090 |
| Washer Types | Plain Flat, Heavy Duty Structural, Spring Lock, Belleville Washers, Tab Washers |
| Size Range | Imperial: #4 to 4" NB | Metric: M3 to M100 |
| Thickness Range | 0.5 mm to 12 mm (Custom gauges available on order) |
| Hardness Range | Annealed: HRB 92 max (201 HBW max) |
| Surface Finishes | Bright Annealed, Passivated, Pickled, Electro-polished, PTFE Coated |
| Certification | EN 10204 3.1 MTR, PMI Testing Report, Hardness Verification |
SS 347 Series Technical Properties & Composition
Chemical Composition of UNS S34700 / S34709 Washers (%)
| Element | SS 347 (UNS S34700) | SS 347H (UNS S34709) |
|---|---|---|
| Carbon (C) | 0.08 max | 0.04 – 0.10 |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Silicon (Si) | 0.75 max | 0.75 max |
| Phosphorus (P) | 0.045 max | 0.045 max |
| Sulfur (S) | 0.030 max | 0.030 max |
| Chromium (Cr) | 17.0 – 19.0 | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 | 9.0 – 13.0 |
| Niobium (Nb / Cb) | 10 x C min to 1.00 max | 8 x C min to 1.00 max |
Mechanical Properties of UNS S34700 / S34709 Washers
| Property / Parameter | SS 347 (S34700) | SS 347H (S34709) |
|---|---|---|
| Tensile Strength (MPa) min | 515 | 515 |
| Yield Strength 0.2% Proof (MPa) min | 205 | 205 |
| Elongation (% in 50mm) min | 40 | 40 |
| Rockwell Hardness B (HR B) max | 92 | 92 |
| Brinell Hardness (HB) max | 201 | 201 |
Equivalent Grades of SS 347 / 347H Washers
| Standard / System | SS 347 | SS 347H |
|---|---|---|
| UNS Designation | S34700 | S34709 |
| Werkstoff Nr. | 1.4550 | 1.4912 |
| Euronorm Name | X6CrNiNb18-10 | X7CrNiNb18-10 |
| JIS Standard | SUS 347 | SUS 347H |
SS 347 vs. SS 347H
| Feature | SS 347 | SS 347H |
|---|---|---|
| Carbon Content | Standard (0.08% max C) | Controlled High Carbon (0.04–0.10% C) |
| Alloy Modifiers | Niobium Stabilized (10x C min) | Niobium Stabilized (8x C min) |
| Max Operating Temp. | Continuous up to 816°C | Continuous service above 537°C |
| Weld Heat Zone | Prevents carbide precipitation | Superior creep-rupture capability |
| Best Used For | Chemical reactors & heavy welds | Radiant superheaters & boiler tubes |
Why Industries Prefer SS 347/347H Washers
Handles Extreme Heat: Performs reliably in high-temperature equipment up to 816°C without breaking down or warping.
Prevents Joint Leaks: Maintains strong, steady clamping force on bolts, stopping flange leaks during sudden temperature changes.
Resists Corrosion & Oxidation: Built to withstand harsh chemicals, hot gases, and corrosive industrial fluids without rusting.
Longer Service Life: Strong material structure reduces wear and tear, lowering repair costs and downtime for critical machinery.
Smooth & Easy Assembly: Precision-made flat surfaces prevent thread jamming and allow quick, hassle-free installation.
Types of SS 347 Washers
Aurum Overseas supplies a comprehensive range of stainless steel washer configurations manufactured according to standard DIN, ASME, and ISO dimensional tolerances for multiple engineering assemblies.
SS 347/347H Plain Washers
SS 347/347H Spring Washers
SS 347/347H Lock Washers
SS 347/347H Square Washers
SS 347/347H Conical Washers
Key Technical Advantages
Columbium/Niobium Stabilization
Forms stable niobium carbides that bind carbon, leaving chromium fully available for passive corrosion resistance.
Superior Creep Resistance
Elevated carbon control in 347H variants ensures long-term resistance to mechanical deformation under constant elevated stress.
Polythionic Acid Protection
Highly resistant to polythionic acid stress corrosion cracking during maintenance shutdowns in hydroprocessing units.
High Weldability
Eliminates the need for post-weld solution annealing while preserving joint strength in thermal cycles.
Cryogenic Reliability
Maintains structural integrity, toughness, and non-magnetic behavior down to sub-zero temperatures.
Key Applications of SS 347/347H Washers
| Industry Sector | Recommended Grade | Typical Equipment Application | Service Conditions |
|---|---|---|---|
| Chemical Processing | SS 347 / S34700 | Waste heat recovery, chemical reactors | Cyclic elevated heat, aggressive chemical vapors |
| Petrochemical Refining | SS 347H / S34709 | Fluid catalytic cracking, hydrotreating units | Service above 537°C, polythionic acid exposure |
| Power Generation | SS 347H / S34709 | Radiant superheater tubes, steam manifolds | High-pressure thermal steam, extreme mechanical stress |
| Automotive & Marine | SS 347 / S34700 | Heavy-duty exhaust collector rings, risers | Direct engine exhaust gases, rapid thermal cycling |
| High-Temp Fabrication | SS 347 / 347H | Heavy welded pressure vessel flanges | Post-weld thermal stress, high pressure |
Quality Testing & Inspection
As an experienced SS 347/347H Washers Supplier, Aurum Overseas subjects every production batch to rigorous quality checks:
- Chemical Verification: Positive Material Identification (PMI) via XRF testing to verify exact chromium, nickel, and niobium stabilization ratios.
- Intergranular Corrosion Defense: Tested per ASTM A262 Practice E (Monypenny-Strauss test) to guarantee complete resistance to weld-decay.
- Mechanical & Hardness Testing: Proof load, yield strength, and Rockwell B hardness verification (<= 92 HRB) per ASTM A240 standards.
- Dimensional Precision: Laser-micrometer verification of thickness, inner diameter, and outer diameter tolerances per ASME B18.21.1 and DIN 125.
Global Export Markets
Aurum Overseas, an international SS 347/347H Washers Exporter, supplies fully certified UNS S34700 / S34709 Washers to key markets worldwide:
USA
Canada
Mexico
Germany
United
Kingdom
France
Italy
Netherlands
Norway
UAE
Saudi
Arabia
Qatar
Kuwait
Oman
Singapore
Malaysia
Australia
Frequently Asked Questions
SS 347 contains niobium (columbium), which binds carbon into stable niobium carbides. This prevents chromium depletion and intergranular corrosion when operating continuously in the 425°C to 816°C temperature range.
SS 347H features a controlled higher carbon content (0.04%–0.10%), which provides significantly higher creep and stress-rupture strength at service temperatures above 537°C (1000°F).
Their niobium stabilization makes them highly resistant to polythionic acid stress corrosion cracking, which frequently affects unstabilized grades during refining operations and shutdown periods.
Contact Aurum Overseas
Aurum Overseas manufactures and stocks certified SS 347/347H Washers for immediate global dispatch.
Contact our technical sales team for instant pricing, material test reports, and custom size requirements.