Description
Product Detail
Duplex and super duplex steel lap joint flanges are loose backing flanges designed to be used with lap joint stub ends. They allow easy bolt hole alignment and simplify maintenance in piping systems where regular dismantling, inspection or replacement is required. Compared with conventional flange assemblies, they offer installation flexibility while duplex and super duplex materials provide high strength, excellent chloride pitting resistance and improved stress corrosion cracking resistance. Typical applications include offshore pipelines, chemical processing, desalination plants, fire water lines and marine systems.
SASA FLANGE supplies standard and customized lap joint flanges in ASME, EN, DIN, JIS and GB dimensions. Each order can be supported by chemical analysis, mechanical testing, dimensional inspection, PMI testing, EN 10204 3.1 certificate and full heat number traceability. Custom drilling, non-standard dimensions, special sealing surfaces and project-specific marking are available on request.
- ✓Product Name: Duplex Super Duplex Steel Lap Joint Flanges
- ✓Material Grade: ASTM A182 F51, F53, F55, F60 / UNS S31803, S32205, S32750, S32760
- ✓Product Type: Lap Joint Flange for use with stub end
- ✓Main Feature: High strength, excellent pitting and crevice corrosion resistance, easy alignment and dismantling
- ✓Applications: Offshore, seawater handling, chemical plants, desalination, power, marine and water treatment
Product Parameters
| Product Name | Duplex Super Duplex Steel Lap Joint Flanges |
| Material Grade | ASTM A182 F51, F53, F55, F60; UNS S31803, S32205, S32750, S32760 |
| Material Type | Duplex stainless steel / Super duplex stainless steel forged flange |
| Product Form | Lap Joint Flange, loose flange used with stub end |
| Size Range | DN15 – DN1500 (1/2 inch – 60 inch) |
| Pressure Class | Class 150 – 1500 / PN10 – PN100 |
| Sealing Face | Flat Face suitable for lap joint backing flange assembly; custom machining to project requirement |
| Surface Treatment | Natural machined, pickling, passivation, anti-rust protection on machined surfaces |
| Standard | ASME B16.5, ASME B16.47, EN 1092-1, DIN, JIS B2220, GB/T 9119 or customer specification |
| Inspection | Chemical Analysis, Mechanical Test, PMI Test, Dimensional, Visual, NDT on request |
| Certificate | EN 10204 3.1 Material Certificate available |
| Processing Service | Cutting, CNC Machining, Custom Drilling, Custom Size Processing |
Chemical Composition
The following chemical composition data is for general reference for common duplex and super duplex forged flange grades. Actual composition will comply with the applicable ASTM, EN or customer specification and will be confirmed by the mill test certificate and project inspection requirements for each heat number supplied.
| Element | C | Si | Mn | P | S | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| F51 / UNS S31803 % | 0.03 max | 1.00 max | 2.00 max | 0.03 max | 0.02 max | 21.0-23.0 | 4.5-6.5 | 2.5-3.5 | N 0.08-0.20 |
| F55 / UNS S32760 % | 0.03 max | 1.00 max | 1.00 max | 0.03 max | 0.01 max | 24.0-26.0 | 6.0-8.0 | 3.0-4.0 | N 0.20-0.30, Cu 0.50-1.00, W 0.50-1.00 |
Mechanical Properties
Mechanical properties shown below are typical minimum values for forged duplex and super duplex flange grades in the properly solution-annealed condition. Actual results may vary depending on grade, section thickness, heat treatment and applicable standard requirements. Final values are verified by test reports and inspection documents for each supplied batch.
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness | Density |
|---|---|---|---|---|---|
| ASTM A182 F51 | 620 MPa min | 450 MPa min | 25% min | 290HB max | 7.8 g/cm3 |
| ASTM A182 F55 | 750 MPa min | 550 MPa min | 15% min | 300HB max | 7.8 g/cm3 |
Common Size Table
| Size Range | Pressure Class | Sealing Face | Material | Availability |
|---|---|---|---|---|
| DN15 – DN50 | Class 150 – 600 | Lap Joint / FF style backing flange | F51 / F60 | Stock / Production |
| DN65 – DN300 | Class 150 – 900 | Lap Joint / FF style backing flange | F51 / F55 | Stock / Production |
| DN350 – DN600 | Class 150 – 1500 | Lap Joint / FF style backing flange | F51 / F53 / F55 | Production |
| DN700 – DN1500 | Class 150 – 600 | Lap Joint / FF style backing flange | F51 / F55 | Made to Order |
Different Specifications Comparison
| Type | Description | Typical Use |
|---|---|---|
| ASME Lap Joint Flange | Loose flange used with ASME B16.9 stub end, easy to rotate for bolt alignment | Process piping, offshore skids, maintenance-intensive lines |
| EN Lap Joint Flange | European dimensional backing flange matched with EN stub end dimensions | Water treatment, chemical plants, EU-standard piping systems |
| Duplex Lap Joint Flange | Lap joint flange produced in duplex stainless steel for strength and chloride resistance | Brackish water, fire water, general seawater service |
| Super Duplex Lap Joint Flange | Higher alloy lap joint flange for severe chloride and offshore conditions | Desalination, offshore topside, seawater injection and marine service |
Equivalent Standards and International Names
Lap joint flanges can be manufactured according to several international dimensional standards, while the material grade designation may differ by region. Equivalent names below are typical references only. Final selection should be based on the required flange standard, pressure rating, corrosion allowance, forging standard and end-use service conditions specified by the project.
| Standard / Region | Standard Code | Typical Grade / Equivalent |
|---|---|---|
| USA | ASME B16.5 | ASTM A182 F51, F53, F55, F60 |
| Europe | EN 1092-1 | 1.4462, 1.4410 |
| Germany | DIN 2527 / 2566 | X2CrNiMoN22-5-3, X2CrNiMoN25-7-4 |
| Japan | JIS B2220 | SUS329J3L, equivalent duplex grades on request |
| China | GB/T 9119 | 022Cr22Ni5Mo3N, 022Cr25Ni7Mo4N |
Production Process Flow
SASA FLANGE controls each production stage from raw material verification to final inspection to ensure dimensional accuracy, corrosion-resistant material integrity and full traceability for duplex and super duplex lap joint flanges used in demanding industrial piping systems.
- 1. Raw Material Selection
- 2. Forging / Cutting
- 3. Heat Treatment
- 4. Rough Machining
- 5. Finish Machining
- 6. Drilling
- 7. Surface Treatment
- 8. Inspection
- 9. Marking
- 10. Packing
- 11. Delivery
| Process Step | Description | Quality Control Point |
|---|---|---|
| Raw Material | Select certified forging billets or plates | Material certificate and traceability |
| Forging | Hot forging to achieve required shape | Forging temperature and reduction ratio |
| Heat Treatment | Solution annealing and rapid cooling as required by duplex grade | Temperature, soaking time and cooling control |
| Machining | Sealing face, bolt holes, dimensions | Dimensional accuracy and surface finish |
| Inspection | Final inspection before shipment | Dimension, surface, PMI, certificate verification |
Product Inspection
1. Chemical Composition Inspection
Chemical analysis is performed to verify that chromium, nickel, molybdenum, nitrogen and other alloying elements meet the specified duplex or super duplex grade requirements. This inspection helps confirm corrosion resistance and material conformity before machining and shipment. Test results are linked to the heat number and included in the material documentation package.
2. Mechanical Properties Testing
Mechanical testing verifies tensile strength, yield strength, elongation and hardness according to the applicable forging material standard. Duplex and super duplex flanges are checked to ensure the required balance of high strength and toughness after proper heat treatment. Test records are reviewed against customer specifications and relevant ASTM or EN requirements.
3. Dimensional Inspection
Dimensional inspection covers outside diameter, inside diameter, thickness, bolt circle, bolt hole diameter, number of holes and flange facing details according to ASME, EN, DIN, JIS or GB standards. Particular attention is given to fit-up with the matching stub end and to concentricity, flatness and machining quality for reliable installation on site.
4. PMI Testing and Hydrostatic Testing
PMI testing is carried out to confirm the alloy grade of duplex or super duplex flanges and to prevent material mix-up in critical projects. Hydrostatic testing is generally applied to assembled piping components where specified, while flange supply is supported by visual and dimensional inspection, PMI records and EN 10204 3.1 certification for full quality assurance.
Product Packaging
- ✓Wooden Case Packaging: Suitable for high-pressure and large-diameter products
- ✓Pallet Packing with Shrink Wrap: Suitable for batch shipments and standard sizes
- ✓Anti-rust Oil Coating + Waterproof Paper: Used for ocean freight protection
- ✓Individual Plastic Bag + Carton: Used for small fittings and threaded products
- ✓Clear Marking: Grade, size, pressure class, heat number and PO number
Applications
Duplex and super duplex lap joint flanges are widely used in industries where high strength, chloride corrosion resistance and easy dismantling are required. Their loose flange design supports simple alignment during installation and maintenance, making them suitable for aggressive media, offshore conditions and systems with frequent inspection or component replacement.
| Industry | Typical Applications | Why This Product Is Used |
|---|---|---|
| Oil and Gas | Offshore piping, produced water lines, fire water systems, utility piping | Provides chloride resistance, high strength and easier disassembly during maintenance |
| Chemical Processing | Acid handling support lines, process water, corrosive chemical transfer systems | Suitable for corrosive service where reliable sealing and material integrity are required |
| Power Generation | Cooling water systems, FGD auxiliary piping, service water lines | Resists corrosion in wet and chloride-bearing environments and allows easier flange alignment |
| Water Treatment | Desalination piping, RO skids, brine lines, seawater intake and discharge | Super duplex grades offer strong resistance to pitting and crevice corrosion in saline media |
| Marine and Offshore | Ballast systems, seawater cooling, deck piping, offshore module fabrication | Combines marine corrosion resistance with flexible installation and maintenance advantages |
Why Choose SASA FLANGE?
- ✓Professional manufacturer of Lap Joint Flange for global industrial projects
- ✓Customized size, pressure class and material grade according to drawings
- ✓Full standard support: ASME, EN, DIN, JIS, GB, GOST and customer specifications
- ✓Material traceability with heat number control and EN 10204 3.1 material certificate
- ✓Chemical analysis, mechanical testing, PMI testing, hydrostatic and dimensional inspection
- ✓Stock availability for standard items, lead time 3-7 days; custom production 15-30 days
- ✓Export-grade packaging for sea, air and land transportation
- ✓15+ years experience supplying 50+ countries worldwide
FAQ
Q: What is a duplex super duplex steel lap joint flange?
A: A duplex or super duplex lap joint flange is a loose backing flange used together with a stub end. The flange rotates freely around the pipe, making bolt alignment easier during installation. It is commonly selected for corrosive service and systems that require frequent dismantling, inspection or replacement, especially in offshore, chemical and desalination applications.
Q: What materials are available for duplex super duplex steel lap joint flanges?
A: SASA FLANGE commonly supplies ASTM A182 F51, F53, F55 and F60 grades, corresponding to UNS S31803, S32205, S32750 and S32760. Equivalent EN, DIN and GB duplex material designations can also be produced according to project requirements. Material selection depends on chloride level, temperature, design code and expected corrosion resistance in service.
Q: What pressure class is supported?
A: Duplex and super duplex lap joint flanges are typically supplied in ASME Class 150, 300, 600, 900 and 1500, depending on size and standard. For EN and DIN systems, PN10 to PN100 can be produced. The actual available pressure rating depends on flange dimensions, material grade, temperature conditions and the selected international standard.
Q: Can SASA FLANGE supply custom sizes?
A: Yes. SASA FLANGE can manufacture custom sizes, non-standard drilling, special bolt hole orientation, project-specific thickness and matching dimensions for stub ends. We also support custom marking, machining tolerances and special material grades for offshore or corrosive service. Drawings, standards and technical data sheets can be reviewed before production to ensure correct fit and performance.
Q: What certificate is provided?
A: Standard supply includes EN 10204 3.1 material certificate with full heat number traceability. Depending on the order, SASA FLANGE can also provide mill test certificates, chemical analysis results, mechanical test reports, PMI records and dimensional inspection reports. Additional third-party inspection support can be arranged for export projects requiring stricter documentation and quality approval.
Contact Us
If you are looking for duplex super duplex steel lap joint flanges or related custom flange products, please contact SASA FLANGE with your required size, pressure class, material grade, standard, surface treatment, quantity and inspection requirements. Our team will provide professional technical solutions and competitive quotation within 24 hours.
- 📧 Email: sales@sasaflange.com
- 📱 WhatsApp: +86 13764965049
- ☎️ Tel: +86 21 52236361
- 🌐 Website: www.sasaflange.com
