A Reducing Flange is a special flange used to connect a larger pipe to a smaller pipe directly. Unlike standard flanges with the same bore size as the pipeline, reducing flanges have a reduced inner bore to match the smaller pipe diameter.
This design can replace a standard flange plus reducer combination, helping reduce installation space, welding work, material cost, and total pipeline weight.
Reducing flanges are especially useful in pipeline systems where flow direction changes from a large pipe size to a smaller pipe size, or where equipment nozzles and pipeline diameters are different.
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图片建议:放一张横幅图,标题为 MAIN PRODUCTS,下面展示 Reducing Flange、Weld Neck Flange、Blind Flange、Slip On Flange、Plate Flange 等产品。
图片标题:Main Flange Products
| Standard | Type | Class / Pressure Rating | Size Range | Material Options |
|---|---|---|---|---|
| ASME B16.5 | Reducing Flange | Class 150-2500 | NPS 1/2”-24” | ASTM A105, A182, A350 |
| ASME B16.47 | Large Size Reducing Flange | Class 75-900 | NPS 26”-60” | Carbon Steel, Alloy Steel |
| EN 1092-1 | Customized Reducing Flange | PN6-PN100 | DN15-DN4000 | P250GH, S235JR, Stainless Steel |
| DIN | Reducing Flange | PN6-PN100 | DN15-DN2000 | Carbon Steel, Stainless Steel |
| JIS B2220 | Reducing Steel Flange | 5K, 10K, 16K, 20K | DN15-DN1500 | SS400, SUS304, SUS316 |
| Custom Drawing | Non-standard Reducing Flange | Customized | Customized | Customized Materials |
| Sealing Surface | RF, FF, MFM, TG, RJ | - | - | - |
| Coating | Varnish, Black Paint, Anti-rust Oil, Galvanizing | - | - | - |
Additional Specifications:
Reducing flanges are available in a wide range of materials. The material should be selected according to pipeline medium, working pressure, temperature, corrosion environment, and project standard.
Carbon steel reducing flanges are commonly used in oil and gas, water treatment, construction, and general industrial systems. Stainless steel reducing flanges are suitable for chemical, food, pharmaceutical, and corrosive environments. Alloy steel and duplex materials can be used for high-temperature, high-pressure, or special working conditions.
| Material | Grade |
|---|---|
| Carbon Steel | ASTM A105, Q235, S235JR, C22.8, A350 LF2 |
| Alloy Steel | ASTM A182 F1, F5, F9, F11, F12, F22, F91 |
| Stainless Steel | ASTM A182 F304, 304L, F316, 316L, 321 |
| Duplex Steel | F51, F53, F55, S31803, S32205, S32750 |
| Nickel Alloy Steel | Inconel 600, Inconel 625, Incoloy 825, Hastelloy C276 |
| Copper Alloy | CuNi 90/10, CuNi 70/30 |
| Titanium | Grade 2, Grade 5, Grade 7 |

reducing-flange-dimension-drawing
| Dimension Item | Description |
|---|---|
| OD | Outside Diameter |
| Large Bore ID | Bore size matching the larger pipe side |
| Small Bore ID | Bore size matching the smaller pipe side |
| BCD | Bolt Circle Diameter |
| Bolt Hole | Bolt hole quantity and diameter |
| Thickness | Flange thickness |
| Reduced Bore | Transition bore for different pipe sizes |
| Face Type | RF, FF, RTJ, MFM, TG |
Reducing flanges can be manufactured according to standard dimensions or customer drawings. Key dimensions include outside diameter, flange thickness, reduced bore size, bolt circle diameter, bolt hole diameter, number of bolt holes, and sealing face type.
Compact Pipeline Connection
Reducing flanges connect different pipe sizes directly, reducing the need for additional reducer fittings.
Lower Installation Cost
Compared with using a standard flange plus reducer, reducing flanges can reduce welding work, material cost, and installation time.
Space-Saving Design
The compact structure is suitable for equipment connections or pipeline systems with limited installation space.
Flexible Bore Customization
The bore can be customized according to pipe size, wall thickness, and project requirements.
Wide Standard Compatibility
Reducing flanges can be produced according to ASME, EN, DIN, JIS, GOST, and custom drawings.
Reliable Sealing Performance
Accurate machining and suitable sealing face treatment help ensure stable flange connection performance.
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图片建议:放工厂车间、锻造、热处理、机加工、钻孔、包装照片拼图。
图片标题:Reducing Flange Workshop
Oil and Gas Industry
Used for pipeline size transition in oil transmission, gas pipelines, refinery systems, and offshore platforms.
Petrochemical Plants
Suitable for process pipelines where different pipe diameters need to be connected safely and efficiently.
Power Generation
Used in steam, cooling water, and auxiliary pipeline systems.
Chemical Processing
Stainless steel and alloy reducing flanges are suitable for corrosive media and special working conditions.
Water Treatment
Used in pump stations, water supply systems, drainage pipelines, and treatment facilities.
Industrial Equipment Connection
Suitable for connecting equipment nozzles, valves, pumps, and pipelines with different diameters.
Image Position 5: Application Scenarios
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图片标题:Reducing Flange Application Scenarios
Comprehensive Manufacturing Capability
We coordinate forging, heat treatment, machining, drilling, inspection, coating, and packaging under one production system.
Custom Bore Processing
We can manufacture reducing flanges with customized bore sizes, stepped bores, special thicknesses, and non-standard drilling patterns.
International Standards Compliance
Our products meet ASME, EN, DIN, JIS, GOST, and customer drawing requirements.
Wide Material Options
Carbon steel, stainless steel, alloy steel, duplex steel, nickel alloy, copper alloy, and titanium materials are available.
Strict Quality Inspection
Each batch is inspected for material grade, dimensions, bore accuracy, bolt hole alignment, sealing surface, and appearance.
Export Packaging Support
Anti-rust treatment, wooden case packaging, and customized marking are available for international shipment.
Image Position 6: Certificates
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图片标题:Reducing Flange Certificates
Q: What is a Reducing Flange?
A: A reducing flange is a flange used to connect pipes of different diameters. It has a reduced bore to match the smaller pipe size.
Q: Can Reducing Flange replace a reducer fitting?
A: In many pipeline designs, yes. It can replace a standard flange plus reducer combination, saving space and installation cost.
Q: What standards are available?
A: Reducing flanges can be supplied according to ASME B16.5, ASME B16.47, EN 1092-1, DIN, JIS, GOST, and custom drawings.
Q: What materials can be used?
A: Common materials include carbon steel, stainless steel, alloy steel, duplex steel, nickel alloy, copper alloy, and titanium.
Q: Can the bore size be customized?
A: Yes. The reduced bore, stepped bore, thickness, drilling pattern, and sealing face can be customized according to project drawings.
Ready to enhance your piping systems with premium Weld Neck Flange solutions? Contact kevin.zhao@hkflange.com for technical specifications and competitive quotations today.
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