Explore our high-performance forged stainless steel flanges and stub ends, produced in accordance with strict international tolerance frameworks.
In modern high-integrity piping systems, selecting the optimal flanged connection requires balancing mechanical sealing integrity, material economics, and field installation efficiency. A Van Stone Flange (frequently referred to interchangeably in global EPC specifications as a Lap Joint Flange with a Stub End or a Loose Flange System) represents a two-piece mechanical joint assembly. It consists of a wetted component—the stub end—butt-welded directly to the process pipeline, and a non-wetted, freely rotating backing flange that resides behind the lap of the stub end.
This structural decoupling provides profound engineering and financial advantages over monolithic solid weld neck flanges, particularly when conveying aggressive, highly corrosive fluids in industrial processes. Because the fluid contacts only the interior wall and sealing face of the stainless steel stub end, the external backing flange is never exposed to the process media. Consequently, plant engineers can specify high-grade austenitic, duplex, or super duplex stainless steels (such as ASTM A403 WP316L, WP321, or UNS S31803) for the stub end while utilizing economical carbon steel (such as ASTM A105 or Q235B) or ductile iron for the backing flange.
Because the backing flange rotates 360° freely around the stub end hub, field installation crews can align bolt holes effortless without applying torsional stress to the pipe runs, cutting field bolt-up times by over 40%.
In large-bore stainless steel installations (DN200 to DN1200), pairing an austenitic stainless stub end with a carbon steel backing flange reduces raw material costs by up to 55% compared to solid stainless weld neck flanges.
The mechanical decoupling buffers thermal expansion differential stress between the pipe spool and the bolting circle, preventing gasket compression fatigue and bolt creep in cyclic thermal applications.
When torque is applied to the stud bolts, compressive force is transferred from the front face of the backing flange to the back shoulder (radius) of the stub end. This loads the gasket located between the stub end sealing face and the mating flange face. To prevent fatigue failure at the transition corner of the stub end, precision forging practices must maintain a carefully controlled fillet radius ($R$) in compliance with MSS SP-43 or ASME B16.9. A undersized radius induces severe stress concentration spikes under high bolt tension, whereas an oversized radius causes physical interference with the inside bevel of the backing flange. Shanxi Yuxin utilizes 5-axis CNC machining centers to hold the hub-to-lap fillet radius within an exacting tolerance band of ±0.2 mm.
Engineered for full interchangeability with international piping codes including ASME, EN, DIN, and JIS standard frameworks.
| Standard Code | Component Type | Nominal Size (DN / NPS) | Pressure Ratings | Face Finishes / Configurations |
|---|---|---|---|---|
| ASME B16.5 | Lap Joint Flange & Stub End | ½" – 24" (NPS) | Class 150, 300, 600, 900, 1500 | Raised Face (RF), Smooth Finish (125-250 µin AARH) |
| ASME B16.47 Series A/B | Large Diameter Loose Flanges | 26" – 60" (NPS) | Class 75, 150, 300, 600 | Concentric Serrated, Smooth Machined |
| EN 1092-1 Type 02 / 33 | Loose Flange with Weld-on Collar | DN10 – DN1200 | PN6, PN10, PN16, PN25, PN40, PN63 | Type A (Flat Face), Type B1 (Raised Face) |
| MSS SP-43 | Wrought Stainless Stub Ends | ½" – 24" (NPS) | Type A (Standard Lap), Type B, Type C | Long Pattern & Short Pattern Configurations |
| DIN 2642 / DIN 2641 | Loose Flanges for Stub Ends | DN10 – DN1000 | PN10, PN16 | Machined Ring Bore for DIN Collar Mating |
Shanxi Yuxin Casting & Forging Co., Ltd. processes premium electric-arc melted steel billets subjected to secondary AOD (Argon Oxygen Decarburization) refining. This guarantees minimal non-metallic inclusion content and ultra-low sulfur concentration (< 0.015%), preventing intergranular stress corrosion cracking in aggressive fluid conduits.
| Material Grade | UNS / EN Code | Tensile Strength (MPa) | Yield Strength (MPa) | PREN Rating | Primary Service Application |
|---|---|---|---|---|---|
| ASTM A182 / A403 F304L | S30403 / 1.4307 | ≥ 485 | ≥ 170 | ~18.5 | General chemical handling, food processing, cryogenic pipe spools down to -196°C. |
| ASTM A182 / A403 F316L | S31603 / 1.4404 | ≥ 485 | ≥ 205 | ~25.0 | Marine atmospheres, chloride-bearing processes, pharmaceuticals, pulp & paper. |
| ASTM A182 F321 | S32100 / 1.4541 | ≥ 515 | ≥ 205 | ~19.0 | High-temperature operating lines (400°C to 800°C), thermal power plant exhausts. |
| Duplex 2205 (F51) | S31803 / 1.4462 | ≥ 655 | ≥ 450 | ≥ 34.0 | Desalination reverse osmosis headers, offshore oil & gas separators, sour gas lines. |
| Super Duplex 2507 (F53) | S32750 / 1.4410 | ≥ 750 | ≥ 550 | ≥ 42.0 | Aggressive chloride streams, subsea manifolds, high-pressure chemical scrubbers. |
Tailored Van Stone flange configurations solving unique operating challenges across high-consequence global industries.
Continuous process lines conveying hydrocarbons laced with hydrogen sulfide ($H_2S$) require stringent NACE MR0175 / ISO 15156 compliance. Shanxi Yuxin supplies solution-annealed ASTM A182 F316L stub ends with HIC (Hydrogen-Induced Cracking) resistance, combined with epoxy-coated carbon steel loose flanges to withstand aggressive refinery marine atmospheres.
High-pressure seawater reverse osmosis (SWRO) systems operate under intense pitting corrosion conditions. By incorporating Duplex 2205 Van Stone stub ends with hot-dip galvanized backing flanges, EPC contractors reduce system mass and total flange procurement budgets by 38% while guaranteeing 30-year service life against chloride pitting.
Ultra-pure water (UPW) and high-purity chemical distribution lines mandate internal surface roughness below Ra 0.38 µm to eliminate bacterial micro-trapping. We furnish mechanical electropolished 316L Van Stone stub ends designed for quick teardown during clean-in-place (CIP) and sterilize-in-place (SIP) cycles.
Located in Dingxiang County, Shanxi—the world-recognized "Hometown of Forging"—Shanxi Yuxin Casting & Forging Co., Ltd. operates integrated modern manufacturing assets.
Unlike trading entities or intermediary machining shops, Shanxi Yuxin controls every critical step of the metallurgical transformation cycle under one roof. From raw billet cutting, medium-frequency induction furnace heating, closed-die forging, radial-axial ring rolling, normalized/solution heat treatment, to multi-axis CNC finish machining—our internal process ownership guarantees 100% heat number traceability from ingot to final crate.
Every Van Stone flange manufactured at our Shanxi facility complies with internationally recognized pressure vessel codes and quality audit regimes:
Pioneering advanced manufacturing methodologies to meet net-zero carbon mandates and smart plant connectivity requirements.
Integrating Directed Energy Deposition (DED) 3D laser cladding on the sealing face of forged carbon steel stub ends with Hastelloy C276 or Inconel 625. This yields extreme corrosion resistance on wetted faces while retaining forged structural ductility at 40% reduced cost.
Embedding piezo-resistive micro-sensors within the backing flange collar. These sensors communicate real-time stud bolt pre-load, joint vibration, and gasket stress via WirelessHART protocol to edge computing gateways, alerting maintenance teams to flange looseness prior to leak occurrence.
As part of Shanxi Yuxin's decarbonization initiative, our reheating furnaces are transitioning to green hydrogen gas blends. This transition aims for a 60% reduction in Scope 1 carbon footprint during hot forging operations by 2030, supporting international ESG procurement mandates.
A strategic buyer framework for evaluating flange manufacturing partners and mitigating international supply chain risks.
When procuring flanged connections for long-distance piping lines, forward-looking procurement managers calculate TCO across three distinct project phases:
Preventing transit corrosion and mechanical thread damage during ocean freight is critical to project timeline adherence. Shanxi Yuxin enforces robust export packaging protocols:
Navigating global regulatory landscapes requires a manufacturing partner intimately familiar with international pressure vessel directives. Shanxi Yuxin's dedicated engineering export desk provides direct technical alignment across European (PED 2014/68/EU), North American (ASME Section VIII, Canadian CRN registrations), and Middle Eastern (Saudi Aramco / SABIC approved specs) standard frameworks.
Direct communication with certified Senior Metallurgical Engineers. We review project Isometric drawings, bill of materials (BOM), and offer customized material optimization suggestions within 24 hours.
Equipped with CAD/CAM design integration, we forge custom non-standard stub ends, non-standard thickness backing rings, and heavy wall tube sheets up to 3000 mm diameter directly from customer CAD drawings (DWG, STEP, PDF).
Full support for independent third-party inspection (TPI) agency witness points, including TÜV, Lloyd's Register, SGS, Bureau Veritas, and DNV for material testing, non-destructive evaluation, and final dimensional checks.
In-depth technical answers addressing critical procurement and structural design inquiries.
Explore additional forged carbon steel, alloy steel, and stainless steel products engineered for global export project requirements.
Work directly with Shanxi Yuxin Casting & Forging Co., Ltd.—eliminating intermediary markup and securing factory-direct pricing with full EN 10204 3.1 material traceability.
