Explore our ISO 9001 & PED certified flange portfolio manufactured at Shanxi Yuxin Casting & Forging Co., Ltd.
In modern high-pressure piping design, pressure vessel fabrication, and turbomachinery fluid handling, the mechanical joint represents one of the most critical potential failure points. An Integral Flange (classified under European standard EN 1092-1 as a Type 21 Flange and governed in American standards under ASME B16.5 / ASME Section VIII Division 1 Appendix 2) is a specialized class of flange where the flange neck, hub, and ring are forged or cast as an monolithic, indivisible structural unit with the equipment wall or valve body.
Unlike standard loose slip-on or weld neck flanges—where a circumferential field or shop weld joins a separate flange ring to a pipe length—integral flanges eliminate the heat-affected zone (HAZ) adjacent to the flange shoulder. By maintaining continuous grain flow lines generated during precision die forging, integral flange configurations provide exceptional fatigue resistance, superior bending moment capacity, and uniform stress redistribution under cyclic thermal loading.
Technical Distinction: Under ASME Boiler and Pressure Vessel Code (BPVC) rules, an integral flange construction assumes that the flange ring and its supporting neck/hub act as a single continuous beam element. This minimizes stress concentrations at the hub-to-shell junction, allowing for higher design pressure ratings in severe-service applications.
Heavy process industries operating under extreme pressures (Class 900 to Class 2500 / PN100 to PN400) face severe mechanical challenges including hydraulic shock, bending forces from wave action (in offshore operations), and aggressive chemical corrosion. China integral flanges products manufactured by Shanxi Yuxin Casting & Forging Co., Ltd. are engineered specifically to overcome these stress factors:
Continuous thermal exposure up to 600°C combined with high hydrogen partial pressures demands forged integral flanges free of microscopic voiding or grain boundary segregation.
FPSO turrets and subsea manifolds utilize custom forged integral flanges to endure dynamic wave-induced bending moments and saltwater pitting corrosion.
Integrated boiler nozzles and steam turbine connections require full volumetric Non-Destructive Examination (NDE) and strict zero-leakage compliance (TA-Luft / ISO 15848-1).
The global demand for high-integrity integral flanges has shifted towards direct manufacturer partnerships capable of managing the entire value chain—from steel ingot selection and closed-die forging to 5-axis CNC precision machining and full metallurgical testing. Located in Dingxiang County, Shanxi Province—widely recognized as the “Hometown of Forging in China”—Shanxi Yuxin Casting & Forging Co., Ltd. operates an integrated 10,000-ton annual forging infrastructure.
By leveraging localized raw material supply chains (high-purity carbon steel billets, low-alloy grades, austenitic/duplex stainless steel) and state-of-the-art ring-rolling equipment, Chinese manufacturers deliver fully certified integral flanges at competitive total cost of ownership (TCO) without compromising international design compliance.
| Standard / Type | Material Grade | Nominal Size (DN / NPS) | Pressure Class | Facing Options | Key Certifications |
|---|---|---|---|---|---|
| EN 1092-1 Type 21 (Integral Flange) |
P250GH, P280GH, 1.4404 (316L), 1.4462 (Duplex 2205) | DN 15 to DN 2000 | PN 6 to PN 400 | Type A (Flat), Type B1/B2 (Raised), Type C/D (Tongue/Groove) | PED 2014/68/EU, AD 2000-W0, EN 10204 3.1/3.2 |
| ASME B16.5 Hubbed (Integral Design) |
ASTM A105, A350 LF2, A182 F11/F22, A182 F304L/F316L | ½" to 24" | Class 150 to Class 2500 | RF (Raised Face), RTJ (Ring Type Joint), FF (Flat Face) | ASME BPVC Sec VIII, NACE MR0175 / ISO 15156 |
| ASME B16.47 Series A/B (Large Diameter) |
ASTM A105, A350 LF2, A182 F51 / F53 / F55 (Super Duplex) | 26" to 60" | Class 75 to Class 900 | Raised Face (RF), Ring Type Joint (RTJ) | ISO 9001:2015, API 6A Spec Compliant |
| Custom Valve-Integral (OEM Drawing Based) |
AISI 4130, Inconel 625 Clad, Monel 400, Hastelloy C276 | Custom Machined up to Ø3000mm | Up to 15,000 PSI API 10K/15K | Custom API Ring Grooves, O-Ring Recesses | Third Party Witness (TÜV, DNV, SGS, BV) |
Securing high pressure containment requires rigorous testing protocols at every phase of production. Every China integral flange product originating from YUXIN undergoes multi-stage Quality Assurance (QA) aligned with global project specifications:
100% volumetric UT inspection per EN 10228-3 / ASTM A388 ensures complete freedom from internal cracks, hydrogen flakes, or center-line shrinkage flaws.
Handheld XRF analyzer testing verifies alloy element distribution (Cr, Ni, Mo, Cu) to prevent material mix-ups in critical stainless and alloy lines.
Strict control of HRC / HBW hardness limits (HRC < 22) per NACE MR0175 ensures high immunity against Sulfide Stress Cracking (SSC) in sour gas extraction.
Scenario A: Middle East High-Pressure Gas Injection Wells
A major operator in Saudi Arabia required Class 1500 RTJ integral flanges forged directly onto heavy-wall choke valve bodies. Standard welding was prohibited due to post-weld heat treatment (PWHT) constraints in field conditions. YUXIN supplied custom ASTM A350 LF2 Class 2 integral forgings with Charpy V-Notch impact testing verified at -46°C, guaranteeing full mechanical compliance without field welding risks.
Scenario B: North Sea Floating Offshore Units (FPSO)
In subsea suction manifold assemblies, cyclic fatigue caused by ocean currents can lead to bolt relaxation in conventional loose flange assemblies. By standardizing on EN 1092-1 Type 21 integral flanges in Super Duplex UNS S32750 (1.4410), the project achieved a 30% mass reduction alongside zero maintenance over a 15-year continuous operating cycle.
The manufacturing landscape for China integral flanges products is rapidly evolving through digital transformation, environmental stewardship, and advanced metallurgical modeling. Key technical milestones being implemented at Shanxi Yuxin Casting & Forging Co., Ltd. include:
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