Tight-Fit CNC Milled Duplex Stainless Steel Flange
Tight-fit CNC milled duplex stainless steel flanges machined from solid forgings or plate with precision facing, bolt hole drilling, and bore machining to ASME B16.5 / EN 1092-1 dimensional requirements. 2205 and 2507 duplex grades for high-strength, chloride-resistant service in offshore, chemical, and desalination applications. Sizes DN15–DN600 (1/2"–24"), pressure classes 150–2500.
Manufacturing Processes :
CNC turning (multi-axis with live tooling), CNC milling (3/4/5-axis), cylindrical grinding, centerless grinding, honing, thread cutting, broaching, drilling & tapping, EDM wire-cut (partner)Heat Treatment :
Quench & temper | Case hardening / carburizing | Induction hardening | Solution annealing | Vacuum hardening | Nitriding | Stress relieving. Every heat treatment batch ships with time–temperature chart and hardness report.Surface Treatment :
Zinc plating (clear/yellow passivation) | Zinc-nickel alloy | Electroless nickel | Hard chrome plating | Black oxide | Phosphating (MnPO4) | Passivation (ASTM A967) | Electropolishing | Anodizing (aluminum) | Powder coatingCustomizable :
YesOrder(MOQ) :
Prototype: 1–10 pcs (no MOQ for billet-machined parts). Small batch: 10–500 pcs. Series production: 500–50,000+ pcs/month.Specifications
Shengtao's tight-fit CNC milled duplex stainless steel flanges are machined from forged duplex or super duplex stainless steel blanks that have been ultrasonically tested to verify forging integrity before machining begins. The flange is first turned on a CNC lathe to establish the OD, raised face, bore, and facing finish, then transferred to a CNC machining center where the bolt hole circle is drilled and the flange edge is profiled — all in a single integrated manufacturing flow with a common workpiece datum, eliminating the alignment errors that can occur when turning and drilling operations are performed on separate machines with separate setups. This integrated approach is the foundation of our ability to hold bolt hole circle diameter tolerance to ±0.5 mm and individual hole position to ±0.3 mm on flanges up to DN600.
Duplex stainless steel is the material of choice for flanges in environments where both mechanical strength and chloride stress-corrosion cracking resistance are critical — offshore platforms, chemical processing plants, desalination facilities, and sour-service oil and gas installations. 2205 duplex (UNS S31803/S32205) offers roughly double the yield strength of 304/316 austenitic stainless steel, allowing thinner-walled, lighter flanges for the same pressure rating, along with excellent resistance to pitting and crevice corrosion in chloride-containing environments. For the most aggressive service conditions — high-temperature seawater, hot chlorides, and strong reducing acids — 2507 super duplex (UNS S32750) provides a further step up in both strength and corrosion resistance. All material is supplied with EN 10204 3.1 mill test reports and is verified by Positive Material Identification (PMI) using handheld XRF before machining.
Facing finish is machined to the serrated (phonographic) standard of Ra 3.2–6.3 µm (125–250 AARH) as specified by ASME B16.5 for raised-face flanges, providing the controlled surface roughness needed for reliable gasket seating and sealing. The facing is inspected with a profilometer and a visual comparator; flatness is verified to within 0.1 mm per 300 mm. Bolt holes are through-drilled and spot-faced on the back side where required. Each flange is electro-etched with material grade, heat number, pressure class, size, and manufacturer identification in accordance with ASME marking requirements. Contact us with your flange specification for a quotation within 24 hours.
Tight-Fit CNC Milled Duplex Stainless Steel Flange is one of our core strength products. We maintain substantial inventory to ensure rapid delivery and can also customize extra-large diameter seamless pipes according to your specific requirements. Additionally, we provide comprehensive services including spectroscopic analysis, mechanical property testing, pressure testing, and non-destructive testing (NDT).
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Note: If you do not find a Tight-Fit CNC Milled Duplex Stainless Steel Flange that meets your requirements or is suitable for your customer’s project, please contact our manager sales consultant (Email: stsalesman4@stmetal001.com) and send us your specifications and technical parameter files to obtain Customized quotation plan. |
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FAQs
Q: What machined parts and fabrication services does Shengtao provide?
Shengtao is a China-based, ISO 9001-certified one-stop manufacturer delivering precision-machined and fabricated metal parts across 10 product categories:
• CNC Precision Machined Parts — turned, milled, and 5-axis complex components
• Stamped & Formed Metal Parts — progressive die stamping, deep drawing, sheet metal fabrication
• Welded & Fabricated Steel Assemblies — structural weldments, pressure vessel shells, pipe spools
• Hydraulic & Pneumatic Components — honed cylinder barrels, chrome-plated piston rods, valve bodies
• Automotive Precision Parts — drivetrain, suspension, steering, and engine components
• Surface-Treated Steel Parts — mirror polishing, electropolishing, hard chrome, zinc/nickel plating
• Precision Tube & Pipe Machined Parts — tube end machining, honing, pipe spool assemblies
• Laser Cut & Waterjet Cut Parts — precision 2D profiles up to 150 mm thick
• Machined Pipe & Tube Fittings — threaded fittings, forged flanges, custom connectors
• Special Alloy & High-Performance Parts — Inconel, Hastelloy, Titanium, tool steel components
We work from your drawings, providing customized parts — we do not sell standardized off-the-shelf items. Send your RFQ with a drawing to start a quotation.
Q: Can you manufacture custom parts from my engineering drawings? What file formats do you accept?
A: Yes — custom manufacturing to your drawings is our core business. We accept:
• 2D drawings: PDF, DWG, DXF
• 3D models: STEP (.stp), IGES (.igs), SolidWorks (.SLDPRT / .SLDASM), CATIA, Inventor
The process is straightforward:
1. Send your drawing/model with material specification, quantity, and any special requirements.
2. We sign an NDA before reviewing your files.
3. Our engineering team performs a DFM (Design for Manufacturability) review and flags any concerns.
4. We send a formal quotation with price, lead time, and technical notes within 24–48 hours.
We handle everything from raw material sourcing through machining, heat treatment, surface finishing, inspection, and export packaging — delivering parts ready for your assembly line.
Q: What materials can you source and machine for my parts?
A: We source and machine a comprehensive range of metals, all with certified mill test reports (MTR):
Stainless steel: 303, 304, 316, 316L, 321, 410, 420, 430, 2205, 2507 (duplex/super duplex)
Carbon steel: A36, 1020, 1045, A105, A106 Gr.B, API 5L X42–X80, S235, S355
Alloy steel: 4140, 4340, 8620, 42CrMo4, 34CrNiMo6, 20CrMnTi, A387 Gr.11/22
Aluminum: 6061-T6, 7075-T6, 5052, 5083
Tool steel: D2, H13, M2, P20, S7
Nickel alloys: Inconel 600/601/625/718, Hastelloy C-276/C-22, Monel 400
Titanium: Grade 1, Grade 2, Grade 5 (Ti-6Al-4V), Grade 23 (Ti-6Al-4V ELI)
Brass & copper: C36000, C11000, C26000
If your specification calls for a material not listed above, please ask — we work with approved steel mills and can source commercial grades, pressure-vessel grades, and AMS/aerospace grades.
Q: Do you offer welding and fabrication for complex assemblies, including code-compliant work?
A: Yes. Welding and fabrication is a core Shengtao capability, covering single-part weldments through to fully welded structural frames, pressure vessel shells, and pipe spools.
Welding processes: SMAW, GMAW/MIG, GTAW/TIG, SAW (submerged arc), FCAW, orbital TIG
Welder qualifications: AWS D1.1 / D1.6, ASME Section IX, EN ISO 9606
NDE capabilities: 100% VT, PT, MT, UT, RT (X-ray) available, including third-party witness
We fabricate to:
• ASME Section VIII Div.1 — pressure vessels
• ASME B31.1 / B31.3 / B31.4 — power, process, and liquid piping
• AWS D1.1 — structural steel
• PED 2014/68/EU — European pressure equipment
• NACE MR0175 / ISO 15156 — sour service
Every fabrication ships with a full data book: weld map, WPS/PQR, welder qualifications, NDE reports, MTRs, dimensional inspection, and hydrostatic test certificate.
Q: Do you offer engineering support or design feedback on my part drawings?
A: Yes, and we encourage it. Our in-house engineering team reviews every drawing before production and provides DFM (Design for Manufacturability) feedback at no cost:
We check for:
• Machinability: features that are difficult or impossible to produce (e.g., sharp internal corners, unreachable undercuts, extreme aspect ratios)
• Tolerance optimization: identifying dimensions where looser tolerances can reduce cost without affecting function
• Material alternatives: suggesting equivalent grades if the specified material has long lead times or is cost-prohibitive
• Cost reduction opportunities: changes that simplify fixturing, reduce setups, or allow more efficient tooling
This is a value-added service at no extra charge — many customers have reduced per-part cost by 15–30% through DFM suggestions while maintaining full functionality.
We never modify your drawing without your written approval. All DFM suggestions are clearly annotated on a marked-up drawing for your review.
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Note: If you do not find a Tight-Fit CNC Milled Duplex Stainless Steel Flange that meets your requirements or is suitable for your customer’s project, please contact our manager sales consultant (Email: stsalesman4@stmetal001.com) and send us your specifications and technical parameter files to obtain Customized quotation plan. |
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