Explore our primary heavy-duty forged steel flanges manufactured strictly in accordance with ASME, EN, DIN, and JIS standards.
Understanding the role of screwed pipe connections in high-pressure, non-welded industrial infrastructure.
Founded in 1992, Shanxi Yuxin Casting & Forging Co., Ltd. operates within the Zhuangli Enclave Industrial Zone of Dingxiang County, Shanxi Province—globally acclaimed as the “Hometown of Forging in China.” Unlike trading agencies or secondary processors, YUXIN maintains a fully integrated 10,000-ton annual forging facility. Every threaded steel flange is forged from hot-rolled billets, normalized, heat-treated, and precision-machined on multi-axis CNC lathes to guarantee exact thread engagement and zero micro-porosity.
Threaded steel flanges (also referred to as screwed flanges) feature an internal tapered or parallel pipe thread within the flange bore, designed to match external male pipe threads. The main structural advantage of a threaded flange lies in its weldless connection methodology. It enables rapid assembly in hazardous, highly explosive, or heat-restricted environments—such as oil refineries, gas storage units, and chemical processing facilities—where post-weld heat treatment (PWHT) or open flame permits are completely forbidden.
| Flange Type | Joint Mechanism | Welding Requirement | Pressure Range | Ideal Application |
|---|---|---|---|---|
| Threaded (Screwed) Flange | Internal NPT / BSPT / API Threads | None (Weldless) | Class 150 – Class 2500 / PN6 – PN400 | Hazardous explosive zones, low-bore utility, oilfield test loops |
| Weld Neck Flange (WN) | Full Penetration Butt Weld | Mandatory (100% NDT/RT) | Up to Class 2500 / High Fatigue | High pressure, severe cyclic thermal shock, cross-country pipelines |
| Slip-On Flange (SO) | Double Fillet Weld (Inside/Outside) | Mandatory Fillet Welds | Class 150 – Class 1500 / PN6 – PN100 | Moderate pressure commercial piping, HVAC, water utilities |
| Lap Joint Flange (LJ) | Loose Flange with Stub End | Welded Stub End Only | Class 150 – Class 600 | Frequent dismantlement, stainless steel systems with carbon flange |
Key technological shifts reshaping the global procurement landscape for industrial piping components.
Global Engineering, Procurement, and Construction (EPC) firms are rapidly shifting toward off-site modularization. Pre-fabricated piping skids demand standardized threaded components that can be bolted and torqued on-site without field welding, significantly reducing labor expenses, site insurance costs, and commissioning schedules.
With oil and gas extraction expanding into deeper, highly corrosive reservoirs containing Hydrogen Sulfide (H₂S), threaded flanges must strictly comply with NACE MR0175 / ISO 15156 standards. Forged carbon steels (ASTM A105N) and alloy grades (A182 F11/F22) now undergo specialized vacuum degassing and controlled heat treatment to resist sulfide stress cracking (SSC).
Traditional manual thread tapping is being phased out in high-tier manufacturing. CNC single-point thread chasing ensures micrometric accuracy in thread pitch, taper angle, and flank geometry. Advanced optical thread gauges and 3D coordinate measuring machines (CMM) ensure 100% thread engagement accuracy across ANSI B1.20.1 and ISO 7-1 specifications.
In high-pressure screwed connections exceeding 3,000 PSI (Class 900+), thread surface roughness must be kept below Ra 1.6 µm. YUXIN utilizes customized carbide thread-chasing inserts and automated coolants during CNC machining to prevent micro-galling during field torque-up, eliminating leak paths without requiring aggressive thread sealants.
What international procurement leaders, EPC engineers, and stockists demand when sourcing Chinese forged flanges.
Enterprise buyers require strict adherence to international dimensional and pressure standards. YUXIN's engineering matrix fully accommodates:
In compliance with global quality guidelines, every single shipment from YUXIN is accompanied by an EN 10204 3.1 Mill Test Certificate (MTC) (or EN 10204 3.2 third-party witnessed on request). MTCs report full chemical composition (spectrometric analysis), mechanical tensile/yield strengths, elongation, Brinell/Rockwell hardness, Charpy V-notch impact values down to -40°C, and heat treatment logs.
| Material Category | Material Grade Standard | Operating Temperature Range | Traceability Marking |
|---|---|---|---|
| Forged Carbon Steel | ASTM A105 / A105N, Q235B, P250GH, S235JR | -29°C to +425°C | Die Stamped Heat No., Size, Class, Standard |
| Low-Temperature Carbon Steel | ASTM A350 LF2 Class 1 / Class 2 | -46°C to +345°C | Impact Tested Stamp (-46°C @ 20J) |
| Stainless Steel | ASTM A182 F304 / F304L, F316 / F316L, F321 | -196°C to +650°C | Color Coded End Caps + Laser Etching |
| Duplex & Super Duplex | ASTM A182 F51 (UNS S31803), F53 (S32750) | -50°C to +300°C (High Corrosion) | EN 10204 3.1 / PMI Spectrometer verified |
Tailored forged flange solutions engineered for demanding operational environments.
For high-pressure Christmas tree manifolds and separator skids where hot welding presents gas explosion hazards, YUXIN provides API 5B and ASME Class 1500/2500 screwed flanges forged from ASTM A350 LF2 low-temperature steel, ensuring micro-crack resistance under rapid pressure relief.
Utilizing dual-certified ASTM A182 F316/316L stainless steel, YUXIN fabricates precision NPT threaded flanges featuring raised face (RF) or ring-type joint (RTJ) profiles. These units withstand aggressive acids, solvents, and sea-water cooling loops without pitting or intergranular decay.
For commercial HVAC distribution, district heating networks, and high-pressure fire mains, YUXIN delivers galvanized and epoxy-coated carbon steel screwed flanges compliant with EN 1092-1 Type 12, offering quick mechanical assembly and lower total life-cycle maintenance costs.
Single-site quality management ensuring absolute structural integrity from billet to crate.
100% optical emission spectrometry (OES) chemical verification of incoming round bars before cutting.
Hydraulic forging presses shape steel billets, refining grain flow and maximizing mechanical toughness.
Computerized electric furnaces perform normalizing, quenching, or tempering to reach specified hardness.
Multi-axis CNC lathes cut precise serrated raised faces and single-point cut NPT/BSPT threads.
Ultrasonic Testing (UT) & Magnetic Particle Inspection (MPI) detect internal voids or micro-cracks.
Deep heat-number stamping, material grade, pressure rating, and logo etched around the outer rim.
Anti-rust yellow varnish, black painting, or hot-dip galvanizing, fitted with plastic thread caps.
Solid fumigation-free plywood cases with inner waterproof foil wrapping for seaworthy transport.
Global credentials verified by international inspection bodies for seamless project integration.
YUXIN holds valid PED 2014/68/EU (Pressure Equipment Directive) certificates alongside AD 2000-Merkblatt W0 / TRD 100 approvals assessed by TÜV Rheinland / TÜV CERT. This empowers European distributors and plant operators to legally import and deploy YUXIN flanges across EU jurisdictions.
Our commitment to consistent forging quality is demonstrated through decade-long OEM supply agreements with global industrial leaders including Manfred Geldbach Flansch und Fitting GmbH, Samsung Engineering, Van Leeuwen Pipe and Tube, and China National Petroleum Corporation (CNPC).
YUXIN actively participates in international trade expositions worldwide. Our technical engineering executive team engages directly with European stockists, EPC contract buyers, and refinery engineers at events such as Tube Düsseldorf (Germany) to negotiate strategic supply framework contracts.
Advancing next-generation flange engineering for emerging energy transition infrastructure.
As global energy networks transition toward hydrogen blending, standard NPT threads face increased risk of micro-molecule leakage. YUXIN R&D is developing dual-seal screwed flange geometry featuring localized fluoropolymer secondary O-ring grooves to guarantee zero-leakage performance under 100% pure H₂ transport conditions.
In collaboration with industrial IoT developers, YUXIN is prototyping heavy-duty forged flanges with machined internal cavities designed to accommodate micro strain gauges and piezoresistive pressure sensors. This empowers plant managers to monitor real-time bolt pre-load and joint stress remotely.
Targeting carbon reduction, YUXIN is upgrading its Dingxiang manufacturing facility with solar-powered induction heating furnaces and closed-loop water recovery systems, aiming for a 35% reduction in embodied carbon per ton of finished forged flange by 2028.
Direct technical answers from Shanxi Yuxin's Senior Metallurgical & Export Engineering Desk.
Browse our extended catalog of high-pressure weld neck, lap joint, stub end, and expansion joint flanges.
