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ASME B16.47 Series A Class 300 Welding Neck Flanges
Material: Carbon Steel, Stainless Steel, Alloy Steel, Duplex Stainless Steel
Thickness: According to ASME B16.47 Series A Class 300
Standard: ASME B16.47 Series A
Pressure Class: Class 300
Flange Type: Welding Neck Flange
Flange Face Type: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) upon request
Connection: Butt Weld
Manufacturing Process: Forging and Machining
ASME B16.47 Series A Class 300 Welding Neck Flanges are large-diameter forged pipe flanges manufactured according to ASME B16.47 Series A dimensional requirements. They feature a long tapered hub and butt-weld connection, providing excellent structural strength, reliable sealing performance, and resistance to high pressure and temperature.
The tapered hub gradually transfers stress from the flange to the pipe, reducing stress concentration at the flange connection. This makes welding neck flanges particularly suitable for demanding pipeline systems involving pressure fluctuations, temperature changes, vibration, and mechanical loads.
ASME B16.47 Series A Class 300 Welding Neck Flanges are widely used in oil and gas, petrochemical processing, chemical plants, power generation, offshore engineering, water treatment, pressure vessels, and large-diameter industrial pipeline systems.
Pressure Range: Class 300
Size Range: NPS 26" – NPS 60"
Flange Face Type: Raised Face, Flat Face, RTJ upon request
Connection: Butt Weld
Manufacturing Process: Forging and CNC Machining
ASME B16.47 Series A Class 300 Welding Neck Flanges Descriptions
ASME B16.47 Series A Class 300 Welding Neck Flanges are heavy-duty pipeline connection components designed for large-diameter piping systems.
The defining feature of a welding neck flange is its tapered hub. The hub is butt welded directly to the pipe, creating a smooth transition between the flange bore and pipe wall. This structure distributes mechanical stress more evenly and improves the fatigue resistance of the connection.
Compared with slip-on flanges, welding neck flanges provide superior structural strength and sealing reliability. They are especially suitable for applications involving high pressure, high temperature, thermal cycling, vibration, and hazardous process media.
ASME B16.47 Series A establishes standardized outside diameters, bolt circles, bolt-hole arrangements, hub dimensions, flange thicknesses, and sealing-face dimensions for large-diameter steel flanges.
Here is a detailed feature and performance table for ASME B16.47 Series A Class 300 Welding Neck Flanges:
| Feature / Performance | Description |
|---|---|
| Type | Welding Neck Flange |
| Standard | ASME B16.47 Series A |
| Pressure Class | Class 300 |
| Material | Carbon Steel, Stainless Steel, Alloy Steel, Duplex Stainless Steel |
| Sizes | NPS 26" – NPS 60" |
| Flange Face | Raised Face, Flat Face, RTJ upon request |
| Connection Method | Butt Weld |
| Advantages | High structural strength, excellent stress distribution, reliable sealing, strong fatigue resistance |
| Production Process | Raw Material Inspection → Cutting → Forging → Heat Treatment → Machining → Drilling → Beveling → Inspection → Marking → Surface Treatment → Packing |
| Product Testing | Chemical Analysis, Mechanical Testing, Dimensional Inspection, UT, MT, PMI, Hardness Testing and Third-Party Inspection when required |
| Production Equipment | Forging Hammers, Hydraulic Presses, Heat Treatment Furnaces, CNC Lathes, Drilling Machines and Testing Equipment |
| Application | Oil & Gas, Petrochemical, Chemical Processing, Power Generation, Offshore, Water Treatment and Industrial Pipeline Systems |
ASME B16.47 Series A Class 300 Welding Neck Flange Dimensions
Class 300 Dimensions | ASME B16.47 Series A Flange
All dimensions are in inches.
| Nominal Pipe Size | Outside Diameter (O) | Bolt Circle (W) | Raised Face Diameter (R) | Number of Holes | Diameter of Holes | Bore (B) | Top of Hub (A) | Hub Diameter (X) | Minimum Fillet Radius (r) | Minimum Thickness (T) | Length Thru Hub (Y) | Approx. Weight (lbs) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 26 | 38.25 | 34.50 | 29.50 | 28 | 1.75 | Specified by purchaser | 26.00 | 28.38 | 0.38 | 3.12 | 7.25 | 605 |
| 28 | 40.75 | 37.00 | 31.50 | 28 | 1.75 | Specified by purchaser | 28.00 | 30.50 | 0.44 | 3.38 | 7.75 | 745 |
| 30 | 43.00 | 39.25 | 33.75 | 28 | 1.88 | Specified by purchaser | 30.00 | 32.56 | 0.44 | 3.62 | 8.25 | 870 |
| 32 | 45.25 | 41.50 | 36.00 | 28 | 2.00 | Specified by purchaser | 32.00 | 34.69 | 0.44 | 3.88 | 8.75 | 1005 |
| 34 | 47.50 | 43.50 | 38.00 | 28 | 2.00 | Specified by purchaser | 34.00 | 36.88 | 0.50 | 4.00 | 9.12 | 1145 |
| 36 | 50.00 | 46.00 | 40.25 | 32 | 2.12 | Specified by purchaser | 36.00 | 39.00 | 0.50 | 4.12 | 9.50 | 1275 |
| 38 | 46.00 | 43.00 | 40.50 | 32 | 1.62 | Specified by purchaser | 38.00 | 39.12 | 0.50 | 4.25 | 7.12 | 695 |
| 40 | 48.75 | 45.50 | 42.75 | 32 | 1.75 | Specified by purchaser | 40.00 | 41.25 | 0.50 | 4.50 | 7.62 | 840 |
| 42 | 50.75 | 47.50 | 44.75 | 32 | 1.75 | Specified by purchaser | 42.00 | 43.25 | 0.50 | 4.69 | 7.88 | 950 |
| 44 | 53.25 | 49.75 | 47.00 | 32 | 1.88 | Specified by purchaser | 44.00 | 45.25 | 0.50 | 4.88 | 8.12 | 1055 |
| 46 | 55.75 | 52.00 | 49.00 | 28 | 2.00 | Specified by purchaser | 46.00 | 47.38 | 0.50 | 5.06 | 8.50 | 1235 |
| 48 | 57.75 | 54.00 | 51.25 | 32 | 2.00 | Specified by purchaser | 48.00 | 49.38 | 0.50 | 5.25 | 8.81 | 1380 |
| 50 | 60.25 | 56.25 | 53.50 | 32 | 2.12 | Specified by purchaser | 50.00 | 51.38 | 0.50 | 5.50 | 9.12 | 1530 |
| 52 | 62.25 | 58.25 | 55.50 | 32 | 2.12 | Specified by purchaser | 52.00 | 53.38 | 0.50 | 5.69 | 9.38 | 1660 |
| 54 | 65.25 | 61.00 | 57.75 | 28 | 2.38 | Specified by purchaser | 54.00 | 55.50 | 0.50 | 6.00 | 9.94 | 2050 |
| 56 | 67.25 | 63.00 | 59.75 | 28 | 2.38 | Specified by purchaser | 56.00 | 57.62 | 0.50 | 6.06 | 10.25 | 2155 |
| 58 | 69.25 | 65.00 | 62.00 | 32 | 2.38 | Specified by purchaser | 58.00 | 59.62 | 0.50 | 6.25 | 10.50 | 2270 |
| 60 | 71.25 | 67.00 | 64.00 | 32 | 2.38 | Specified by purchaser | 60.00 | 61.62 | 0.50 | 6.44 | 10.75 | 2470 |
Notes:
- All dimensions are in inches.
- These flanges are furnished with a 1/16" raised face unless otherwise specified.
- Bore dimensions are specified by the purchaser according to the mating pipe.
- Standard bore can be supplied unless otherwise specified.
- Customized bore, facing, bevel, and machining requirements are available.
Welding Neck Flanges
A Welding Neck Flange is characterized by its long tapered hub, which gradually transitions from the flange body to the pipe wall.
The flange is connected to the pipe through a full-penetration butt weld. This provides a strong, continuous connection and allows mechanical stress to be distributed gradually between the pipe and flange.
The tapered hub reduces stress concentration around the welding area, helping improve resistance to fatigue, thermal expansion, vibration, and pressure fluctuations.
Because of these characteristics, welding neck flanges are commonly used in critical piping systems involving:
- High pressure
- High temperature
- Severe temperature fluctuations
- Hazardous fluids
- Vibration
- Cyclic loading
- Large-diameter pipelines
ASME B16.47 Series A Class 300 Welding Neck Flanges are particularly suitable for oil and gas transmission systems, petrochemical facilities, chemical processing plants, offshore pipelines, power stations, and other demanding industrial applications.
Advantages of ASME B16.47 Series A Class 300 Welding Neck Flanges
Excellent Structural Strength
The long tapered hub gradually transfers stress from the flange to the adjoining pipe, helping minimize stress concentration around the welded connection.
This makes welding neck flanges suitable for demanding high-pressure and high-temperature piping systems.
Reliable Sealing Performance
The accurately machined sealing face provides a stable gasket seating surface. When matched with the correct gasket and bolting system, Class 300 Welding Neck Flanges provide dependable sealing performance.
Strong Fatigue Resistance
The smooth transition between the flange hub and pipe helps reduce localized stresses caused by vibration, thermal cycling, pressure variation, and mechanical loads.
This gives welding neck flanges excellent fatigue resistance in demanding operating environments.
Standardized Dimensions
ASME B16.47 Series A standardizes the major flange dimensions, including outside diameter, bolt circle, bolt-hole pattern, flange thickness, hub dimensions, and sealing face.
This provides reliable compatibility with corresponding piping systems and equipment.
Suitable for Large-Diameter Pipelines
ASME B16.47 Series A Class 300 Welding Neck Flanges are designed for large-diameter piping systems from NPS 26" through NPS 60".
They provide a strong connection solution for large pipelines that require higher pressure capability.
Wide Material Selection
Class 300 Welding Neck Flanges can be manufactured from carbon steel, stainless steel, alloy steel, duplex stainless steel, and special material grades according to project requirements.
Applications
Oil and Gas Industry
ASME B16.47 Series A Class 300 Welding Neck Flanges are extensively used in oil and gas transmission pipelines, processing facilities, compressor stations, refineries, storage terminals, and associated equipment.
Their butt-welded construction provides the mechanical strength required for large-diameter pipelines carrying oil, natural gas, and other hydrocarbons.
Petrochemical Industry
Petrochemical processing involves high pressures, elevated temperatures, and aggressive operating conditions.
Class 300 Welding Neck Flanges are used for process piping, reactors, heat exchangers, storage systems, pressure vessels, and equipment connections where strong and reliable flange joints are required.
Chemical Processing
Chemical plants use welding neck flanges in pipelines transporting corrosive, hazardous, or high-temperature process media.
Stainless steel, alloy steel, and duplex stainless steel materials can be selected according to corrosion and temperature requirements.
Power Generation
Welding Neck Flanges are used in steam lines, cooling systems, condensate piping, process water systems, and auxiliary piping in power plants.
Their strong hub design makes them suitable for systems exposed to pressure, temperature variation, and vibration.
Offshore and Marine
Offshore platforms and marine installations use large-diameter welding neck flanges in seawater, oil, gas, cooling, and process piping systems.
Corrosion-resistant materials and special coatings can be provided according to marine operating environments.
Industrial Manufacturing
ASME B16.47 Series A Class 300 Welding Neck Flanges are also used in pressure vessels, pumps, valves, compressors, heat exchangers, machinery, water treatment systems, and general industrial pipelines.
Why Choose Us
ASME B16.47 Manufacturing Capability
We manufacture large-diameter Welding Neck Flanges according to applicable ASME B16.47 Series A dimensional requirements.
Our production range includes Class 150, Class 300, and other pressure classes for different industrial applications.
products can also be supplied according to ASME B16.5, EN, DIN, JIS, AWWA, BS, GOST, and other international standards.
Comprehensive Production Capabilities
Our integrated manufacturing facilities cover:
Raw Material Inspection → Cutting → Forging → Heat Treatment → Rough Machining → CNC Machining → Drilling → Beveling → Surface Finishing → Testing → Marking → Packaging
Integrated production allows us to maintain consistent control over dimensional accuracy, material quality, machining quality, and final inspection.
Large-Diameter Flange Manufacturing
We manufacture large-diameter forged Welding Neck Flanges for pipelines, pressure vessels, valves, pumps, and heavy industrial equipment.
Standard and customized sizes can be manufactured according to ASME dimensional requirements, drawings, and project specifications.
Multiple Material Options
Available materials include:
- Carbon Steel
- Stainless Steel
- Alloy Steel
- Duplex Stainless Steel
- Special Material Grades
Material certificates can be supplied according to project requirements.
Quality Assurance
Our ASME B16.47 Series A Class 300 Welding Neck Flanges can undergo:
- Visual Inspection
- Dimensional Inspection
- Chemical Composition Analysis
- Mechanical Property Testing
- Ultrasonic Testing (UT)
- Magnetic Particle Testing (MT)
- Positive Material Identification (PMI)
- Hardness Testing
- Hydrostatic or project-specific testing when applicable
- Third-Party Inspection
Inspection documents and material certificates can be supplied according to customer requirements.
International Supply Experience
With experience supplying international industrial markets, we understand the documentation, dimensional tolerances, material requirements, inspection procedures, packaging specifications, and technical requirements involved in global flange projects.
COMPANY PROFILE
Shanxi HongKai Forging Co., Ltd. is located in Dingxiang County, Shanxi Province, China, an important manufacturing area for forged flanges.
The company has approximately 20 years of experience in the flange and forging industry and has an annual production capacity of approximately 20,000 MT.
We have comprehensive manufacturing capabilities covering forging, heat treatment, machining, physical and chemical testing, surface treatment, marking, packaging, and shipment.
Our flange products can be manufactured according to major international standards including:
ASME B16.5 / ASME B16.47 / EN 1092-1 / DIN / JIS and other international standards.
We manufacture carbon steel, stainless steel, alloy steel, duplex stainless steel, and customized forged flanges for customers in oil and gas, petrochemical, power generation, chemical processing, water treatment, marine, pressure vessel, machinery, and other industrial sectors.
FAQ
Q: What is an ASME B16.47 Series A Class 300 Welding Neck Flange?
A: It is a large-diameter forged flange manufactured according to ASME B16.47 Series A dimensional requirements. It has a tapered hub and is butt welded directly to the pipe to provide a strong and reliable connection.
Q: What size range is available?
A: Standard ASME B16.47 Series A Class 300 Welding Neck Flanges covered here range from NPS 26" to NPS 60".
Q: What does Class 300 mean?
A: Class 300 is the ASME pressure class designation for the flange. Actual allowable working pressure depends on material group and operating temperature rather than Class 300 representing a fixed 300 psi pressure.
Q: Why are Welding Neck Flanges used in high-pressure systems?
A: The tapered hub and full-penetration butt weld provide a smooth stress transition between the flange and pipe. This helps reduce stress concentration and improves strength and fatigue resistance.
Q: What materials are available?
A: Common materials include carbon steel, stainless steel, alloy steel, and duplex stainless steel. Special grades can also be manufactured according to project requirements.
Q: What flange facings can be supplied?
A: Raised Face is commonly supplied. Flat Face and Ring Type Joint configurations can also be manufactured when permitted by the applicable design and project specification.
Q: What is the standard raised-face height?
A: The referenced dimensional table specifies that these flanges are furnished with a 1/16" raised face unless otherwise specified.
Q: How is the bore dimension determined?
A: The bore is generally selected according to the mating pipe dimensions and project requirements. The referenced table lists the bore as Specified by purchaser.
Q: What industries use ASME B16.47 Series A Class 300 Welding Neck Flanges?
A: Typical industries include oil and gas, petrochemical, chemical processing, power generation, offshore engineering, marine systems, pressure vessels, water treatment, and other large industrial pipeline systems.
Q: Can customized Welding Neck Flanges be manufactured?
A: Yes. We can manufacture customized flange bore dimensions, facing types, bevels, materials, bolt-hole arrangements, coatings, markings, testing requirements, and other dimensions according to customer drawings or technical specifications.
Q: Can you provide inspection certificates?
A: Yes. Material certificates, dimensional reports, mechanical test reports, UT, MT, PMI, hardness testing, and third-party inspection documentation can be supplied according to customer requirements.
Contact Us
Ready to discuss your ASME B16.47 Series A Class 300 Welding Neck Flange requirements?
Contact our technical team for dimensional confirmation, material selection, customized manufacturing, inspection requirements, technical support, and quotations.
Shanxi HongKai Forging Co., Ltd.
Address: Cuijiazhuang Industrial Park, Dingxiang County, Shanxi Province, China
Telephone: +86 13716747092
Email: kevin.zhao@hkflange.com
Please provide your required NPS size, material grade, pipe schedule/bore, flange facing, quantity, coating, inspection requirements, and delivery destination for a quotation.
Clear Communication, and Reliable Technical Support