Engineered to ASME B16.5, EN 1092-1, DIN, and JIS standards. Direct factory export with 100% material traceability.
As global processing plants, offshore platforms, and chemical refineries scale up operating pressures and embrace aggressive fluid media, selecting the correct flange connection becomes a primary safety and operational consideration. A Stainless Steel Slip On Flange (SO Flange) is designed to slide over the outer diameter of a pipe and is secured by two fillet welds—one on the internal hub cavity and one on the outer rim of the flange face.
Unlike Weld Neck (WN) flanges that feature a long tapered hub distributing mechanical stresses directly to the pipe wall, Slip On flanges offer a compact, cost-effective profile. The double-fillet weld construction creates a rigid mechanical joint capable of resisting internal pressures up to Class 1500 (depending on material grade and nominal size). The internal bore of a slip-on flange is slightly larger than the outside diameter (OD) of the mating pipe, allowing for precise alignment before welding without requiring complex pipe end beveling.
Manufactured in Dingxiang County, Shanxi—recognized globally as the “Hometown of Forging in China”—Shanxi Yuxin Casting & Forging Co., Ltd. (established in 1992) integrates advanced closed-die forging, automated ring rolling, continuous heat treatment, and precision CNC machining under a unified ISO 9001 and PED 2014/68/EU quality governance model. This prevents material porosity and ensures superior grain flow structures compared to cast alternatives.
| Feature / Parameter | Slip On Flange (SO) | Weld Neck Flange (WN) | Socket Weld Flange (SW) |
|---|---|---|---|
| Welding Method | Double Fillet Weld (Inside & Outside) | Single Full Penetration Butt Weld | Single Fillet Weld (Outside only) |
| Installation Complexity | Low (No pipe end beveling required) | High (Requires precise bevel alignment) | Moderate (Requires expansion gap setting) |
| Fatigue Resistance | Moderate (Approx. 1/3 of WN Flanges) | High (Excellent under cyclic loads) | Moderate (Prone to gap corrosion) |
| Bore Alignment | Easy self-alignment over pipe OD | Must match pipe inside diameter (ID) | Pipe fits into socket counterbore |
| Cost Efficiency | High (Lower material & machining cost) | Moderate (Higher manufacturing cost) | High (Small bore sizes 1/2" to 2") |
| Typical Applications | Low-to-Medium Pressure, Utility & Process Lines | High Pressure, Severe Cyclic & Sour Service | High Pressure, Small Bore Piping Systems |
The corrosion resistance, mechanical strength, and elevated-temperature longevity of a stainless steel slip-on flange depend heavily on the chemical stoichiometry of the forging billet and subsequent solution heat treatment.
The standard alloy choice for general industrial service, food processing, and municipal water treatment. Grade 304L (low carbon, C ≤ 0.030%) prevents chromium carbide precipitation during welding, preserving intergranular corrosion resistance along the heat-affected zone (HAZ).
Enhanced with 2.0% to 3.0% Molybdenum, ASTM A182 F316/F316L flanges deliver superior resistance to chloride-induced pitting and crevice corrosion. Ideal for marine environments, offshore topsides, and chemical processing handling active acids.
Combining dual-phase ferritic and austenitic microstructures, UNS S31803 / S32205 (2205) and UNS S32750 (2507) yield yield strengths twice that of standard 316L. Excellent stress corrosion cracking (SCC) resistance in severe oilfield and desalination operations.
| Grade (UNS) | Tensile Strength (MPa) | Yield Strength (MPa) | Cr (%) | Ni (%) | Mo (%) | Heat Treatment Protocol |
|---|---|---|---|---|---|---|
| F304 (S30400) | ≥ 515 | ≥ 205 | 18.0 - 20.0 | 8.0 - 11.0 | - | Solution Anneal @ 1040°C + Water Quench |
| F304L (S30403) | ≥ 485 | ≥ 170 | 18.0 - 20.0 | 8.0 - 12.0 | - | Solution Anneal @ 1040°C + Water Quench |
| F316 (S31600) | ≥ 515 | ≥ 205 | 16.0 - 18.0 | 10.0 - 14.0 | 2.0 - 3.0 | Solution Anneal @ 1040°C + Rapid Cool |
| F316L (S31603) | ≥ 485 | ≥ 170 | 16.0 - 18.0 | 10.0 - 15.0 | 2.0 - 3.0 | Solution Anneal @ 1040°C + Rapid Cool |
| F51 / 2205 (S31803) | ≥ 620 | ≥ 450 | 21.0 - 23.0 | 4.5 - 6.5 | 2.5 - 3.5 | Solution Anneal @ 1020-1100°C + Water Quench |
Engineering, Procurement, and Construction (EPC) managers and global flange distributors face dual pressures: maintaining rigorous quality compliance under ASME/EN standards while mitigating supply chain disruption risks.
As green energy infrastructures (such as hydrogen transport pipelines, carbon capture storage systems, and LNG liquefaction plants) expand, global procurement is shifting from carbon steel (A105) toward high-alloy stainless steels and duplex grades that withstand cryogenic temperatures down to -196°C and corrosive wet-gas environments.
Leading buyers prioritize factories offering direct mill certificates (EN 10204 3.1/3.2) over third-party trading intermediaries. Direct factory supply from Shanxi Yuxin reduces landed component cost by 15-22% while ensuring 100% heat traceability back to the original ladle refining furnace.
Project schedules demand fast lead times for custom non-standard dimensions. Shanxi Yuxin maintains dedicated forging die inventory for over 3,000 standard configurations and provides expedited 15-day production cycles for custom drawing-based slip-on flanges up to 120" (DN3000).
Different process industries demand customized flange surface finishes, facing types, and material certifications. Below is an overview of how Shanxi Yuxin customizes slip-on flanges for critical global installations.
For hydrogen sulfide (H2S) rich environments in refining units, Shanxi Yuxin supplies F316L and Duplex 2205 slip-on flanges tested for Sulfide Stress Cracking (SSC) and Hydrogen Induced Cracking (HIC). Facing options include Raised Face (RF) with a 125-250 µin AARH serrated finish to ensure leak-free seal performance with spiral wound gaskets.
Offshore platforms require maximum resistance against salt spray atmospheric corrosion and seawater immersion. We manufacture 316L and Super Duplex 2507 slip-on flanges with precise hub wall thickness to withstand high vibration and bending moments induced by wave action on piping headers.
Sanitary applications demand smooth surface profiles and non-contaminating materials. YUXIN provides mirror-polished or electro-polished 304L/316L slip-on plate flanges (EN 1092-1 Type 01) with internal roughness Ra < 0.8 µm to prevent bacterial buildup in CIP (Clean-In-Place) systems.
High-pressure reverse osmosis (SWRO) facilities require cost-effective, high-reliability pipe connections. Slip-on flanges forged from 316L or 2205 duplex offer the optimal economic balance between upfront capital expenditure and 30+ years of operational durability against brine corrosion.
Quality assurance at Shanxi Yuxin is built upon a 7-stage quality gate system, ensuring zero defect shipment for safety-critical pipeline networks.
100% Optical Emission Spectrometry (OES) chemical analysis and PMI (Positive Material Identification) on all incoming stainless steel round bars prior to heating.
Closed-die forging and CNC ring rolling refine internal grain structure, eliminating voids, inclusions, and structural directional weaknesses.
Computerized continuous solution annealing furnaces guarantee precise temperature hold and water-quench cycles per ASTM A961 / EN 10204.
High-precision multi-axis CNC lathes machine flange sealing faces, bolt hole circles, and hub bores to tight tolerances (±0.5mm on pitch circle diameter).
Ultrasonic Testing (UT) for internal defect detection, Dye Penetrant Testing (PT) for surface crack inspection, and Brinell/Rockwell hardness testing.
Deep-stamp hard marking of Heat Number, Size, Class, Standard, and Grade. Accompanied by EN 10204 3.1 Mill Test Certificates (3.2 optional via TÜV/SGS).
As global manufacturing aligns with decarbonization targets, Shanxi Yuxin is leading the transition toward low-emission forging and smart digital quality management.
Integrating 3D laser scanning coordinate measurement machines (CMM) directly onto the production line to perform 100% automated dimensional checks for flange thickness, bolt hole layout, and face flatness before export packing.
Upgrading forging furnaces to natural gas and clean electric induction heating, lowering carbon intensity per ton of finished forged flange by 35%. Recyclable steel scrap management guarantees zero material waste during machining operations.
Explore our comprehensive range of plain, slip-on, lap joint, and custom forged pipe components.
In-depth answers addressing design rules, pressure ratings, installation steps, and export compliance.
While both flanges slide over the pipe before welding, a Slip-On Flange (ASME B16.5 / EN 1092-1 Type 12) typically features a forged hub that extends from the flange back. This hub provides structural reinforcement, improving fatigue resistance under pressure cyclic loads. A Plate Flange (EN 1092-1 Type 01) is a flat ring without a hub, used primarily in lower-pressure systems such as water distribution and low-temperature HVAC lines.
According to ASME B31.3 Process Piping codes, Slip-On flanges must be welded both internally and externally. The external fillet weld connects the flange hub to the outer pipe wall, taking the primary structural load. The internal fillet weld seals the end of the pipe inside the flange cavity to prevent process fluid from creeping into the crevice between the pipe OD and flange bore, which could cause crevice corrosion or joint failure over time.
For standard marine applications exposed to salt spray, Grade 316L (UNS S31603) with 2.0-3.0% Molybdenum is recommended. For high-salinity seawater intake systems, subsea pipelines, or reverse osmosis plants, Duplex 2205 (UNS S31803) or Super Duplex 2507 (UNS S32750) provides superior Pitting Resistance Equivalent Number (PREN ≥ 40), offering maximum immunity against localized pitting and stress corrosion cracking.
We produce all standard flange facings, including Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ), Tongue & Groove (T&G), and Male & Female (M&F). For Raised Face flanges, we offer standard stock finishes: serrated concentric or spiral grooves with roughness Ra 3.2 µm to 6.3 µm (125 to 250 µin AARH) for soft gaskets, or smooth finishes (Ra < 1.6 µm) upon request.
Every shipment from Shanxi Yuxin includes a complete EN 10204 3.1 Material Test Certificate (MTC) detailing heat number, chemical composition, mechanical test results (tensile, yield, elongation, impact values at sub-zero temperatures), solution annealing heat treatment records, NDT reports (UT/PT), and dimensional check sheets. Third-party inspection (EN 10204 3.2) by TÜV, SGS, DNV, or Lloyd's Register is available upon request.
Standard size flanges (1/2" to 24") in 304L/316L from stock blanks ship within 7 to 15 days. Forged-to-order non-standard flanges or custom drawing components up to 120" (3000 mm) take 20 to 35 days depending on material grade and heat treatment requirements. We support low MOQ for trial orders and distributor stock replenishment.
