Explore our top-tier catalog of certified slip-on, weld neck, lap joint, and custom-engineered pressure components.
In modern process piping design, selecting the right flange component dictates not only installation efficiency but also long-term mechanical reliability under operational stress. Among all pipe flange configurations governed by ASME B16.5, ASME B16.47, and EN 1092-1 specifications, the Slip-On Flange (SO Flange) remains one of the most widely deployed piping elements globally. Engineered to slide over the outer diameter of matching pipe work, a slip-on flange is positioned so that the pipe end sets back inside the flange face by approximately 1/16 inch (1.6 mm), allowing for dual-fillet welding—both internally and externally.
As a leading Chinese forging manufacturer established in 1992 in Shanxi's renowned forging industrial hub, Shanxi Yuxin Casting & Forging Co., Ltd. (YUXIN) operates an integrated production line dedicated to forging carbon steel, stainless steel, alloy steel, and duplex slip-on flanges. Understanding the subtle trade-offs between Slip-On (SO) flanges and Welding Neck (WN) flanges is paramount for EPC procurement managers, piping designers, and QA/QC inspectors seeking optimal cost-to-performance metrics.
Core Technical Advantage of Slip-On Flanges: Slip-On flanges offer a lower initial material cost compared to Weld Neck flanges while simplifying cut-to-length alignment during field fit-up. The double-fillet weld configuration absorbs angular misalignment and eliminates the need for precise pipe end beveling prior to welding.
From a stress-analysis perspective, the slip-on flange exhibits lower strength under internal hydrostatic pressure and dynamic fatigue loading compared to a hubbed weld neck flange. Under ASME Code calculations (Section VIII Division 1, Appendix 2), the calculated strength of a slip-on flange under internal pressure is approximately two-thirds (67%) that of a corresponding weld neck flange, while its fatigue life under thermal or mechanical cycling is roughly one-third (33%).
However, for pressure classes ranging from Class 150 to Class 1500 (and PN6 to PN100 under EN 1092-1), precision-forged slip-on flanges manufactured by YUXIN provide complete structural integrity when installed with properly executed internal and external fillet welds. The internal fillet weld seals the joint against crevice corrosion, while the external fillet weld carries the longitudinal piping loads.
Because the pipe slides directly into the hub of the SO flange, alignment is fast and straightforward. Alignment crews can easily adjust the rotational angle of bolt holes before tack welding.
Slip-on flanges require less raw forging material weight than weld neck flanges with long tapered hubs, drastically reducing capital expenditure on large-diameter utility and chemical lines.
YUXIN produces SO flanges with Raised Face (RF), Flat Face (FF), and Ring Type Joint (RTJ) facings, with smooth or concentric serrated finishes (125–250 µin AARH) tailored to exact gasket specifications.
Leveraging thirty-three years of localized industrial cluster integration in Dingxiang, Shanxi — the "Hometown of Forging in China."
Our mill maintains long-term strategic procurement agreements with premier domestic steel mills (Baosteel, TISCO, Shougang). Fully verified chemical heats ensure precise carbon equivalent (CE) control for superior field weldability.
From closed-die forging to automated CNC turning and multi-spindle drilling, all production steps remain inside YUXIN's owned facilities. 100% single-site oversight eliminates third-party quality risks.
Producing 10,000 metric tons of finished flanges annually, YUXIN holds standardized carbon steel blanks (A105 / Q235B) in stock, guaranteeing rapid dispatch times within 7 to 15 days for standard export orders.
Rigorous NDT testing, heat number traceability, and European pressure vessel accreditations built for Tier-1 EPC projects.
YUXIN flanges are audited and certified under PED 2014/68/EU and AD 2000-Merkblatt W0 / TRD 100 by TÜV CERT. Each shipment is accompanied by an authentic EN 10204 3.1 Mill Test Certificate (MTC) detailing melt heat number, chemical composition, mechanical tensile strength, yield point, elongation, and Charpy V-notch impact values.
For upstream oilfield exploration and sour gas processing facilities containing hydrogen sulfide (H2S), YUXIN supplies slip-on and weld neck flanges compliant with NACE MR0175 / ISO 15156 and NACE MR0103 standards. Materials undergo rigorous HIC (Hydrogen-Induced Cracking) and SSC (Sulfide Stress Cracking) testing to prevent catastrophic hydrogen embrittlement.
Comprehensive engineering matrix across international dimensional standards and metallurgical grades.
| Dimensional Standard | Nominal Size Range | Pressure Class / Rating | Common Material Grades | Facing Types |
|---|---|---|---|---|
| ASME B16.5 | 1/2" to 24" (DN15 - DN600) | Class 150, 300, 600, 900, 1500 | ASTM A105, A350 LF2, A182 F304/304L, F316/316L | RF (Raised Face), FF (Flat Face), RTJ |
| ASME B16.47 Series A / B | 26" to 60" (DN650 - DN1500) | Class 75, 150, 300, 600, 900 | ASTM A105N, A350 LF2 Class 1, ASTM A182 F51/F53 | RF, FF |
| EN 1092-1 (Type 12 SO Hubbed) | DN10 to DN2000 | PN6, PN10, PN16, PN25, PN40, PN63, PN100 | P245GH, P250GH, P280GH, 1.4301, 1.4404, 1.4571 | Type B1, Type B2, Type C, Type D |
| DIN Standards (DIN 2527 / 2576) | DN10 to DN1000 | PN6 to PN40 | RSt37-2, C22.8, 1.4306, 1.4435 | Form C, Form D, Form E |
| JIS B2220 | 10A to 1500A | 5K, 10K, 16K, 20K, 30K | SS400, SFVC2A, SUS304, SUS316 | RF, FF |
From offshore topside modules to municipal waterworks, where slip-on flanges provide optimal performance.
Widely deployed in low-pressure hydrocarbons, utility cooling loops, nitrogen purge networks, and storage tank headers where severe thermal shocks are absent.
Used extensively in low-pressure steam lines, condenser circulating water systems, and auxiliary feed loops requiring economical, leak-free flange connections.
Specified for ballast water treatment networks, fuel transfer lines, and firemain systems on commercial vessels, FPSOs, and offshore platforms.
The global flange manufacturing sector is undergoing a profound transformation driven by carbon neutrality mandates, digital supply chain requirements, and ultra-clean energy transport protocols. As the industry advances toward 2030, three core technology trends are reshaping slip-on flange design and manufacturing:
With global investment accelerating in Green Hydrogen production and Carbon Capture, Utilization, and Storage (CCUS), flanges must resist gaseous hydrogen embrittlement. YUXIN is pioneering ultra-low carbon forged stainless steels (F316L with controlled Nickel-equivalent balance) and micro-alloyed carbon steels tested for zero micro-fissure permeability at high gas pressures.
To ensure absolute dimensional uniformity across high-volume procurement orders, manual machining is being replaced by automated CNC turning centers integrated with dynamic laser tool measurement. This guarantees slip-on bore tolerances within ±0.2 mm, eliminating field fit-up jams during pipe insertion.
Modern EPC contractors demand instant validation of material origin. YUXIN integrates QR-coded heat traceability directly onto the outer flange rim. Scanning the physical flange instantly retrieves the raw billet ladle analysis, heat treatment chart, ultrasonic test report, and 3.1 MTC from our cloud-based Quality System.
Expert responses from YUXIN's Senior Forging Engineers and Metallurgists.
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