What is EN1092-1 Weld Neck (WN) Flange?

Weld Neck Flanges, designated as Type 11 in EN1092-1, feature a long tapered neck that is butt-welded directly to the pipe. This design creates a strong, integral connection that provides excellent stress distribution and fatigue resistance. Unlike slip-on or threaded flanges, WN flanges are specifically engineered for demanding applications involving high pressure, temperature extremes, or cyclic loading conditions.

EN1092-1 WN Flange Dimensions: Reference for DN80

For the commonly used DN80 (3-inch equivalent) size, here are the key dimensions across different pressure classes:

Note: For complete dimension tables (including pipe OD, sealing face diameter, and weights) across all PN classes up to PN 400, refer to the official EN10921 standard or contact our technical team with your specific DN/PN requirement.

Advantages of EN1092-1 WN Flanges

1. Superior Strength & Fatigue Resistance

The full-penetration weld between the neck and pipe creates a joint as strong as the pipe itself, ideal for cyclic loading and highpressure service.

2. Optimized Stress Distribution

The tapered hub smoothly guides stresses away from the weld zone into the flange ring, reducing peak stress concentrations and extending service life.

3. Reliable Sealing Performance

Compatible with Raised Face (RF), Flat Face (FF), and Ring-Type Joint (RTJ) sealing surfaces. When paired with suitable gaskets (e.g., spiral-wound or ring-joint gaskets), they ensure leak-tight integrity even under thermal cycling.

4. Full DN/PN Dimensional Compliance

Follows universal Nominal Diameter (DN) and Pressure Nominal (PN) sizing, enabling seamless connection with valves, pumps, and equipment from any ENcompliant supplier.

5. Ease of Inspection & NDT

The extended neck allows straightforward visual and nondestructive examination (NDT) of the weld, supporting quality assurance and predictive maintenance.

6. Broad Material & Pressure Range

Available in carbon steel, stainless steel, and alloy steel grades, with pressure ratings from PN 2.5 to PN 400, covering nearly all industrial pressure needs.

Potential Material Selection for EN1092-1 WN Flanges

Note: All materials must be supplied with appropriate certification (EN 10204 3.1/3.2) to verify compliance with EN1092-1 requirements.

Where EN1092-1 Weld Neck Flanges Are Essential

• Oil & Gas Industry: Pipeline connections, wellhead equipment, and processing facilities where high pressure and reliability are critical.
• Power Generation: Boiler connections, steam turbine inlets, and high-energy piping systems requiring high-temperature resistance.
• Chemical & Petrochemical: Processing equipment handling corrosive, toxic, or hazardous fluids where leak-tight integrity is paramount.
• Marine Applications: Shipboard piping systems exposed to corrosive seawater and dynamic loading conditions.
• Water Treatment Plants: High-pressure pump discharges, filter systems, and distribution networks requiring durable connections.
• Pharmaceutical & Food Processing: Sanitary systems where material purity and cleanability are essential.

Conclusion

EN1092-1 Weld Neck Flanges represent the gold standard for high-integrity pipe connections. Their welded construction, tapered-hub design, and full compliance with European dimensional and material standards make them the preferred choice for engineers who prioritize safety, longevity, and leak-free performance.

For projects requiring certified EN1092-1 Type 11 flanges—whether in carbon steel, stainless, or high-temperature alloys—partner with a supplier that provides full material traceability (EN 10204 3.1/3.2) and technical support.

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Flanges List

EN1092-1 Standard

EN 1092-1 is the European standard for circular steel flanges with nominal sizes from DN 10 to DN 4000. This standard covers pressure ratings from PN 2.5 to PN 400 and temperature ranges from -50°C to +600°C. As part of the broader European pressure equipment directive framework, EN 1092-1 provides specifications for flange dimensions, materials, pressure-temperature ratings, and sealing surfaces.

The standard classifies flanges into multiple types based on their construction and application requirements. Among these, Type 11 flanges represent a specialized category designed for specific industrial applications requiring robust performance under demanding conditions.

EN1092-1 Type 11 Flanges

Type 11 flanges, as defined in EN 1092-1, are welding neck flanges with a raised face and serrated finish. These flanges feature:

• Long tapered hub that provides stress distribution
• Welding bevel for butt welding to piping
• Raised face (typically 1-2 mm height)
• Serrated finish (spiral or concentric grooves) for improved gasket retention
• Full penetration weld capability for high-integrity connections

Key Characteristics of EN1092-1 Type 11 Flanges

• Pressure Ratings: Available in PN 6, PN 10, PN 16, PN 25, PN 40, PN 63, PN 100, PN 160, PN 250, PN 320, and PN 400
• Temperature Range: Suitable for -50°C to +550°C depending on material grade
• Size Range: DN 10 to DN 2000
• Bolt Hole Configuration: Even number of bolt holes following EN 1092-1 drilling patterns

EN10222-2 P280GH Material

P280GH is a pressure vessel steel plate material specified in EN 10222-2 standard. This material is specifically designed for pressure equipment operating at elevated temperatures.

P280GH Chemical Composition

P280GH Mechanical Properties

Advantages of EN 1092-1 Flanges in P280GH

• Cost-Effectiveness: Non-alloy steel provides good properties at lower cost
• Weldability: Easily welded to carbon steel piping without special procedures
• Temperature Performance: Suitable for most industrial applications up to 400°C
• Availability: Widely available in European markets
• Standard Compliance: Fully compliant with European pressure equipment directives

Inspection Photos

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The customer specifically requested that all flanges undergo solution annealing—a critical step for enhancing corrosion resistance and ensuring uniform mechanical properties.

At ZIZI, we understand the importance of heat treatment in stainless steel products. Our production team strictly adheres to ASME B16.5 standards and performs solution annealing to ensure superior performance, a smooth surface finish, and durability in harsh environments. Every flange we deliver reflects our commitment to quality, precision, and customer satisfaction.

Products List:

Inspection photos

ASME B16.5 Class 300 Weld Neck Flange

An Class 300 ASME B16.5 Weld Neck Flange is a type of high-pressure pipe flange designed to connect piping systems securely and withstand elevated temperatures and pressures.
The “Weld Neck” design features a long tapered hub that provides reinforcement at the weld area, reducing stress concentration and ensuring excellent structural integrity.

This flange type is commonly used in oil & gas, petrochemical, power generation, and offshore industries, where reliable and leak-free connections are critical.

Specification of ASME B16.5 Weld Neck Flanges

ASTM A182 F316 Forged Flange Chemical Composition

ASTM A182 F316 Forged Flange Mechanical Property

Class 300lb Weld Neck Flange Dimensions & Weight

Solution Treatment of Flanges

Solution treatment (or solution annealing) of flanges is a key heat treatment process used to improve the properties of certain materials (especially stainless steel and nickel-based alloy flanges), particularly corrosion resistance and machinability.

Which flanges require solution treatment?

Not all flanges require solution treatment; primarily stainless steel flanges, such as:

Austenitic stainless steel flanges such as 304, 304L, 316, 316L, 321, and 347

Special corrosion-resistant alloy flanges (such as Inconel, Duplex, and Hastelloy)

Note : A solution annealing temperature above 1950 °F [1065 °C] may impair the resistance to intergranular corrosion after subsequent exposure to sensitizing conditions in F 321, F 321H, F 347, F 347H, F 348, and F 348H. When specified by the purchaser, a lower temperature stabilization or resolution annealing shall be used subsequent to the initial high temperature solution anneal (see Supplementary Requirement S10)

SS316 Weld Neck Flange Benefits

High Pressure & Temperature Resistance
Excellent Leak Prevention
Enhanced Durability
Versatile Applications

Applications

Oil & Gas Pipelines

Petrochemical Processing Plants

Power Generation Systems

Water Treatment Facilities

High-Pressure Steam Lines

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What are Weld Neck Flanges?

Weld neck flanges (WN flanges) are pipe connection components characterized by their weld neck design, which achieves high-strength, high-seal integrity connections within piping systems through butt weld to the pipe. weld neck flanges possess an extended neck section welded directly to the pipe. This neck design not only enhances connection strength but also provides a smoother fluid passage, reducing flow resistance. The flange sealing face is the critical interface for connecting the weld neck flange to its mating flange or equipment. Common sealing face types include flat face (FF), raised face (RF), female face (FM), and tongue and groove (TG). Different flange face types suit varying sealing requirements and operating conditions. Weld neck flanges feature uniformly distributed bolt holes for securing connections with mating flanges via bolts and nuts. The number, size, and arrangement of bolt holes comply with standard specifications to ensure connection reliability and interchangeability.

The manufacturing process for weld neck flanges includes raw material preparation, forging or casting, machining, heat treatment, and non-destructive testing. Forging and casting are the primary methods for shaping these flanges. Forged flanges feature dense microstructure, high strength, and excellent toughness; cast flanges are suitable for producing large-sized or complex-shaped components. Machining ensures dimensional accuracy and surface finish; heat treatment relieves residual stresses while enhancing mechanical properties and corrosion resistance; non-destructive testing detects internal defects and cracks.

What is a Raised Face Flange?

Raised Face Flange (RF Flange) is a type of pipe connection component featuring a sealing surface elevated above the bolt hole plane, forming a raised annular area. This design primarily concentrates the preload force on the gasket, applying greater pressure across a smaller contact area to achieve a more reliable seal and effectively prevent fluid leakage. Due to their outstanding sealing performance, RF flanges are among the most common and widely used flange sealing face types in industrial piping systems.

Features of RF Weld Neck Flanges

High Strength and Sealing Performance: The raised face structure ensures uniform gasket compression, making it suitable for high-pressure applications.

Welding Stability: The weld neck is butt-welded to the pipe, delivering high strength and fatigue resistance.

High Temperature and Corrosion Resistance: Available in carbon steel, stainless steel, alloy steel, and other materials to meet diverse operational requirements.

Wide Application: Commonly used in piping systems requiring frequent disassembly and high sealing standards.

Weld Neck Flange Standard Specification

ASME B16.5

Size: 1/2 inch to 24 inches

Pressure: 150#, 300#, 600#, 900#, 1500#, 2500#

ASME B16.5 is a widely recognized and used standard published by the American Society of Mechanical Engineers (ASME). This standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods for specifying openings for pipe flanges and flanged fittings.

ASME B16.47A

Size: 26 inches to 60 inches

Pressure: 150#, 300#, 400#, 600#, 900#

ASME B16.47 A covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for large-diameter steel pipe flanges from NPS 26 to NPS 60. Compared to the B series, these flanges are typically thicker, heavier, and feature larger bolt circles and bolt sizes. They are generally considered more robust and capable of withstanding greater external loads.

ASME B16.47B

Size: 26 inches ~ 60 inches

Pressure: 75#, 150#, 300#, 400#, 600#, 900#

The ASME B16.47 standard covers two series of large-diameter steel flanges, one of which is ASME B16.47B, titled “Large Diameter Steel Flanges: NPS 26 to NPS 60 Metric/Inch Standard.” These flanges are typically lighter and thinner, with smaller bolt circles and bolt sizes, requiring more but smaller fasteners.

EN 1092-1

Size: DN 10 to DN 4000

Pressure: PN 2.5, 6, 10, 16, 25, 40, 63, 100, 160, 250, 400

EN 1092-1 is the European standard for steel circular flanges used to connect piping systems and equipment. This standard applies to flanges for pipes, valves, fittings, and other piping components, and is widely adopted in Europe and internationally.

JIS B2220

Size: 10A ~ 1500A

Pressure: 5K, 10K, 16K, 20K, 30K, 40K

JIS B2220 is a Japanese Industrial Standard (JIS) for steel pipe flanges. This standard is published by the Japanese Standards Association (JSA).

DIN 2631 to DIN 2635

Size: DN 10 ~ DN 1000+

Pressure:

They are German Industrial Standard (DIN) that specifies welding neck flanges . This type of flange attaches to a piping system by butt welding the pipe directly to the flange neck. This design provides excellent stress distribution and is suitable for higher pressure and temperature applications.

Material & Grades of Forged Flanges :

Carbon Steel Raised Face Weld Neck Flange :
ASTM A105 / A105N,ASTM A350 LF2 / LF3, A694 F42 / 46 / 52 / 56 / 65 / 70

Alloy Steel Raised Face Weld Neck Flange :
ASTM / ASME A/SA 182 & A 387 F1, F5, F9, F11, F12, F22, F91

Stainless Steel Raised Face Weld Neck Flange :
ASTM A 182, A 240 F 304, 304L, 304H, 316, 316L, 316Ti, 310, 310S, 321, 321H, 317, 347, 347H, 904L

Duplex & Super Duplex Steel Raised Face Weld Neck Flange :
ASTM / ASME A/SA 182 F 44, F 45, F51, F 53, F 55, F 60, F 61

Copper Alloy Steel Raised Face Weld Neck Flange :

 ASTM SB 61 , SB62 , SB151 , SB152 UNS No. C 70600 (Cu-Ni 90/10), C 71500 (Cu-Ni 70/30), UNS No. C 10100, 10200, 10300, 10800, 12000, 12200

Nickel Alloy Raised Face Weld Neck Flange :
ASTM SB564, SB160, SB472, SB162 Nickel 200 (UNS No. N02200), Nickel 201 (UNS No. N02201), Monel 400 (UNS No. N04400), Monel 500 (UNS No. N05500), Inconel 800 (UNS No. N08800), Inconel 825 (UNS No. N08825), Inconel 600 (UNS No. N06600), Inconel 625 (UNS No. N06625), Inconel 601 (UNS No. N06601), Hastelloy C 276 (UNS No.N10276), Alloy 20 (UNS No. N08020)

ASME B16.5 Weld Neck Flange Dimension

Weld neck flanges are primarily available in sizes ranging from 1/2’’ to 24’’ (DN15 to DN600). They are manufactured to ASME B16.5 standards and are rated for pressure classes 150, 300, 600, 900, and 1500.

Class 150 lb Weld Neck Flange Dimensions & Weight 

Application of RF Weld Neck Flange

Oil and Gas Industry

Chemical and Pharmaceutical Industry

Power and Boiler Systems

Marine and Offshore Engineering

Mechanical and Metallurgical Industries

How to Select and Install Raised Face High Neck Flanges?

Material: Select alloy steel or carbon steel matching the pipeline material to ensure connection compatibility and long-term stability. Common materials include ASTM A105, ASTM A182 (F11, F22, F5, F9), etc.

Size and Class: Select appropriate flange dimensions based on the pipeline’s nominal diameter, pressure rating, and fluid temperature.

Installation: Professional installers must ensure quality butt welding between the flange and pipe, and apply correct torque when tightening bolts to guarantee uniform stress distribution across the sealing surface.

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What is ASME B16.5 Standard?

ASME B16.5 Standard covers pressure-temperature ratings,materials,dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are:

Flange with rating class designations 150#,300#,400#,600#,900#,and 1500#in sizes NPS % through NPS 24. Flanges with rating class designation 2500 in sizes NPS % through NPS 12.

Weld Neck Flange

What is ASME B16.5 Weld Neck Flange?

ASME B16.5 weld neck flange, is a kind of flange that can relocate stress to the pipes, ensuring a decrease in high-stress concentration at the bottom of the weld neck flange. There are two welding neck flanges designs the first type is used with wipes while the second, longer type cannot be used with pipes but with a process plant. The flange comprises of a round fitting that extends beyond the rim of the circumference.

There are many pressure levels for ASME B16.5 weld neck flanges, and the common pressure levels include 150#, 300#, 600#, 900#, 1500#, 2500#.

Class 150 lb Weld Neck Flange Dimensions & Weight 

The material grades of ASME B16.5 weld neck flanges are divided into carbon steel, alloy steel, stainless steel, and duplex stainless steel.

Carcon Steel: ASTM A105 / A105N,ASTM A350 LF2 / LF3, A694 F42 / 46 / 52 / 56 / 65 / 70

Alloy Steel: ASTM A182 F5 / F9 / F11 / F12 / F22 / F91 / F92

Stainless Steel: A182 F304/304L/304H – F316/316L – F317 – F310S – F321 – F347 – F904L

Duplex Stainless Steel: A182 F51/53/55/60

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Forged industrial flange dimensions cover steel material, size, seal face, pressure rating, schedule, standard and flange types.

Flange is one of the most common parts in engineering design. It is a piping design, pipe valve essential parts, but also necessary components for equipment and equipment components (such as manhole, mirror liquid level meter, etc.). In addition, other professions also often use flange joints,such as industrial furnaces, thermal technical, water supply and drainage, heating and ventilation, self-control, etc.

Forged Steel Flange Material

Forged Steel, WCB Carbon Steel, Stainless Steel, 316L, 316, 304L, 304, 321, CR-MO Steel, CR-mo Vanadium Steel, Molybdenum Titanium, Liner, Fluorine-lined Material.

Standard of Pipe Flange

GB, JB, HG, ASME B16.5, BS4504, DIN, JIS

Flange Type

PL Flange,Slip On Flange,Weld Neck Flange, Lap  Joint Flange,Socket Weld Flange,Blind Flange and so on.

PL Flange Dimensions

PL Flange

Advantages:Convenient, manufacture simple, low cost, widely use

Shortcomings: Poor rigidity is poor, not suitable for the chemical process piping system, extremely hazardous occasions which have supply and demand, flammable, explosive and higher vacuum requirements

The sealing type: Flat Face and Raised Face

Slip On Flange Specification

Slip On Flange

Advantages:Easy to install on site and omit the process of rubbing the weld

Shortcomings: The height of Slip On Flange neck is lower, the stiffness and bearing capacity of the flange are higher. Compared with the Weld Neck Flange, the welding workload is large and electrode consumption is high, also can not withstand high temperature,high pressure,repeated bending and temperature fluctuation.

Weld Neck Flange Dimensions

Weld Neck Flange

The sealing type: RF,FM,M,T,G,FF

Advantages:The connection is not easy to deform, seal is good and application is widespread. It is applies in the temperature or the pressure large fluctuation pipeline or the high temperature, the high pressure and the low temperature pipeline, also uses in the transporting expensive medium, flammable explosive medium and poisonous gas pipeline

Shortcomings:Large size, heavy weight, expensive, installation positioning is very difficult. Also easy to bump in transit.

Integral Flange Specification

Integral Flange

The Integral Flange is a flange connect method. Also belongs to weld neck flange. Material has carbon steel, stainless steel, alloy steel and so on. In China standards,”IF” means Integral Flange.

Mostly used in higher pressure pipeline. The manufacture process is generally cast.

In the flange type, an “IF” is the type of integral flange.

Generally it is raised face (RF), if in the flammable, explosive, high and extreme hazards of working conditions, you can choose MFM and TG sealing type.

Socket Weld  Flange Dimensions

SW Flange drawing

Socket Weld Flange

Socket Weld Flange is one end weld on pipe and the other connect by bolts.

The sealing type: RF,MFM,TG,RJ

Application: Boiler Pressure Vessels, Petroleum, Chemical, Shipbuilding, Pharmaceutical, Metallurgy, Machinery, Stamping Elbow Food and other industries.

Used in the pipeline which PN≤10.0MPa，DN≤40

Threaded Flange Specification

Drawing of Thread Flange

Thread Flange

The thread flange is a kind of non welded flange which is machined flange inner hole into thread, and connected with the thread end.of pipe.

Advantages:Compared with Slip On Flange and Weld Neck Flange, the thread flange has the features of easy installation, maintenance, can be used on some sites that not allow welding pipeline. Alloy Steel Flange has enough strength, but difficult to weld, or welding performance is not good,also can choose thread flange.

Shortcomings:Under the condition that pipeline temperature is changed sharply or higher than 260 ℃ and below-45 ℃, to avoid leakage, the threaded flange is not recommended.

Butt Weld Ring Loose Flange Dimensions

Butt Weld Ring Loose Flange

The Butt Weld Ring Loose Flange is movable.Generally supporting in the water supply and drainage fittings, each end of the expansion joint has a flange while sending. Connecting the pipe and equipment by bolts directly in the project.

The purpose of using is to save the material. it is divided into two parts, the pipe part is connected with the pipe, and the other end is made into butt weld ring. The ring flange is made by low grade material, but the pipe part uses the same material as the pipeline.

Advantages

Cost savings. When the material of pipe is special and expensive, the same material of flange is costly.

Not easy to weld or inconvenient to process or require a large strength. such as plastic pipes, glass pipes and so on.

Convenient for construction. While in connection, the flange bolt hole corresponding is not easy to find positive or prevent future replacement equipment, flange bolt hole has changed.

Shortcomings

Withstand low pressure

Low strength at weld ring (especially when thickness is below 3mm)

Flat Weld Ring Loose Flange Specification

PJPR Flange

Flat Weld Ring Loose Flange is movable. Connect with the pipeline and equipment by bolts directly in the project.

The purpose of using is to save cost, it is divided into two parts, the pipe part is connected with the pipe, and the other end is made into stub, and the flange plate is set on the stub.

The flange plate uses the low grade material, but the pipe part uses the same material as the pipeline, achieves the saving purpuse.

Advantages:

Cost savings. When the material of pipe is special and expensive, the same material of flange is costly.

Not easy to weld or inconvenient to process or require a large strength. such as plastic pipes, glass pipes and so on.

Convenient for construction. While in connection, the flange bolt hole corresponding is not easy to find positive or prevent future replacement equipment, flange bolt hole has changed.

Shortcomings

Withstand low pressure

Low strength at weld ring (especially when thickness is below 3mm)

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