Weld Neck Flanges

Understanding your choice of weld neck flanges options

Choosing the right welding neck flanges for your application is crucial for the success of your project. By understanding the different weld neck flange options, materials, and factors to consider, you can make an informed decision. At Guanxin, we offer a wide range of welding-neck flanges options, materials, and sizes to meet your specific application requirements. Contact us today to learn more about our products and services.

What is a weld neck flange?

A weld neck flange, also known as a high hub flange or tapered hub flange, is a specialized type of pipe flange that is designed to be joined to piping systems by welding the pipe to the neck of the flange. These flanges are characterized by their long, tapered hub, which provides added reinforcement and helps to distribute stress over a larger area, reducing the risk of fatigue and failure.

Advantages of WN flanges

• Superior Leak Prevention: Welded neck flanges provide superior sealing, reducing the potential for leaks in high-pressure and high-temperature systems. The tight connection between the flange and pipe helps maintain system integrity and minimizes potential downtime.

• High load carrying capacity: Weld neck flanges are designed to withstand extreme loads for demanding applications in the power generation, petrochemical, oil, and gas industries.

• Improved stress distribution: The extended neck design of weld neck flanges allows for a gradual transition between flange and pipe, reducing stress concentrations and improving the overall durability of the piping system.

• Easy inspection and maintenance: The weld neck flange allows easy access to the piping system for inspection, cleaning, and maintenance, ensuring optimum system performance and minimizing downtime.

Types of Welding Neck Flanges

The following are the primary types of welding neck flanges:

• Long weld neck flanges: long weld neck flanges are characterized by an extended neck, which provides added support and reinforcement for high-pressure applications. This type of flange is ideal for use in high-stress environments, such as those involving high temperatures, pressures, or bending forces. Long weld neck flanges are typically used in industries like petrochemical, oil and gas, and power generation.
• Reducing weld neck flanges: reducing weld neck flanges, also known as reducer flanges, are designed to connect pipes with different diameters. These flanges feature a tapered neck, which allows for a smooth transition between the two pipe sizes, minimizing turbulence and ensuring optimal flow rates. Reducing weld neck flanges are commonly used in situations where pipe diameter changes are required, such as in process piping systems or water treatment facilities.
• Heavy barrel weld neck flanges: heavy barrel weld neck flanges, also known as hbwn flanges, feature a thicker wall thickness and a larger hub diameter compared to standard weld neck flanges. This design provides increased strength and durability, making them suitable for high-pressure and high-temperature applications. Heavy barrel weld neck flanges are often used in the oil and gas, chemical, and power generation industries.
• Expander weld neck flanges: expander weld neck flanges are designed to increase the pipe size, facilitating a transition from a smaller to a larger diameter. These flanges have a tapered neck that allows for a smooth flow transition, reducing turbulence and ensuring optimal flow rates. Expander weld neck flanges are commonly used in applications where an increase in pipe size is necessary, such as in pipelines or process systems.
• Integral weld neck flanges: integral weld neck flanges, also known as nozzle neck flanges or self-reinforced flanges, are forged as a single piece with the pipe, eliminating the need for a separate weld. This design provides increased strength and leak resistance, making them ideal for high-pressure, high-temperature applications. Integral weld neck flanges are often used in the petrochemical, oil and gas, and power generation industries.

Standard for Welding Neck Flanges

The design and manufacturing of WN flanges are governed by the following standards:

• ANSI B16.5 WN Flange
• DIN WN Flange
• EN 1092-1 WN Flange
• BS 4504 WN Flange
• UNI WN Flange
• SANS 1123 WN Flange
• GOST/ГОСТ 33259 WN Flange
• ANSI B16.47 WN Flange
• JIS B2220 WN Flange
• KOREA WN Flange
• BS 10 WN Flange
• AWWA C207 WN Flange
• IWN WN Flange
• MSZ WN Flange
• Australian WN Flange
• French NFE WN Flange
• Norwegian NS WN Flange

Materials of Welding Neck Flanges

Depending on the specific application requirements, weld neck flanges are made from a variety of metal materials, including:

Selecting the Right Weld Neck Flange Material

• Material selection is crucial when choosing weld neck flanges for your piping system. Factors to consider include corrosion resistance, temperature, and pressure requirements. Common materials used for weld neck flanges include:
• Carbon Steel: Offers excellent strength and durability, making it suitable for high-pressure applications.
• Stainless Steel: Provides outstanding corrosion resistance, making it ideal for use in harsh environments or applications where chemical compatibility is essential.
• Alloy Steel: Delivers enhanced resistance to heat and corrosion, making it suitable for high-temperature and high-pressure environments.
• Nickel Alloys: Offer superior corrosion and heat resistance, as well as excellent mechanical properties, making them suitable for use in demanding applications such as aerospace, power generation, and petrochemical industries.

Dimensions of Welding Neck Flanges

The size and dimensions of the weld neck flange must be compatible with the piping system’s components. Ensure that the flange’s nominal pipe size (NPS), outer diameter (OD), and bolt circle diameter (BCD) match the corresponding specifications of the connected equipment.

Dimensions of ASME B16.5 Weld Neck Flanges

ASME B16.5 standard weld neck flanges are available in 1/2” to 24” nominal sizes and in pressure of Class 150#, 300#, 600#, 900#, 1500#, and 2500#. There are many seals facing as Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue-and-Groove (T&G), and Male-and-Female (M&F).

Dimensional Tolerance Welding Neck Flange

Dimensions of ASME B16.47 Series B Weld Neck Flange/WN Flange

Manufacturing process of Welding Neck Flanges

Welding Neck Flanges can be produced by forging, casting. We mainly produce flanges by forging, cutting and rolling processes. We will take you through the step-by-step process of manufacturing weld neck flanges, from the materials used to the final product.

The following type of flange was selected for the qualification. Using the above introduced materials, flanges were manufactured by hummer die forging.

Flange type: 900lbs. 14B WN RF Sch.80 (φ640 x φ318 x H220)

After the materials are cut, they are heated to the desired temperature. This helps to reduce any stresses in the material and makes it easier to shape the flange.

Step 4: Forging

The flanges were manufactured by closed die forging. The forging was performed by two hummers installed in a domestic forging company according to our order requirements. Table 2 shows the forging conditions and Figure 1 shows the pictures of each forging stage.
The forging operation of F51/F60 needed three heats and F53 needed four heats. After forging, the products were quenched immediately in the water. No defect was found on the surface of the products.
Table.1 Chemical compositions (wt%)

Table.2 Hot working conditions

Figure. Forging process

Verification test of the furnace

Before the solution treatment of the flanges, a verification test was carried out in order to confirm the temperature distribution in the furnace. Twenty five (25) dummy flanges were prepared for the test as shown in Figure 2. The measurement result using several thermo couples on the dummy flanges is shown in Figure 3. According to the temperature chart, the maximum temperature difference from target temperature during annealing stage is seven (7) degrees. This means that the furnace is well controlled as a furnace for the solution treatment of stainless steel products.

Figure.2 Dummy flanges for verification

Figure.3 Temperature record chart

Solution treatment of the flanges

Solution treatment was made after forging. Heat cycle is shown in the following: 1,050 ℃ x 2 hours → water quenching.

Surface temperature was monitored at three points of the flange during annealing. All temperature ranges were met within 1,050 ± 7℃ which was satisfactory to standard.

Moreover standard requires that the duration from furnace into quenching bath shall be less than 60sec and the water temperature of the bath shall be below 50℃. According to the measurement results during the quenching, it was confirmed that the transferring time was 53sec and the water temperature was kept under 50℃.

Following the solution treatment, a flange of each material was finished by machining.
There was no difficulty when machining.

After finishing, the penetrant testing (PT) was carried out. No surface defect was found.

Figure.4 and Figure.5 shows the appearance of F51/F60 flange after PT.

The following investigations were carried out according to standards:

• 1) Tensile test
• 2) Impact test
• 3) Corrosion test
• 4) Microstructure observation
• 5) Ferrite content
• 6) Hardness (only for F53)

Sampling locations except hardness measurement are indicated in Figure 5.

Position 1 is specified at middle of hub and position 2 at middle of flange respectively.

Tensile test
Tensile test results at room temperature are shown in Table 3. At every position, properties are satisfactory to the requirements of standards.
Table.3 Tensile test results

Impact test
Charpy 2mm V-notch tests were carried out at -46 C. Sampling locations were pos. 1 and pos.2 as shown in Figure 5. At each location, the specimens were sampled in axial and tangential directions.
The results are shown in Table 4 with requirements of standards. All results meet the requirements successfully.
However, in the case of F51/F60 material, the results in axial direction at pos.2 are just above the minimum requirements. Therefore further study will be desired in order to increase the impact toughness in this condition.
Table.4 Impact test results

Corrosion test
Corrosion tests were carried out according to ASTM G48 Method A- Ferric Chloride Pitting Test using the specimens sampled at pos.1 and pos.2. Testing conditions were 25 °C x 24 hrs for F51/F60 and 50 °C x 24 hrs for F53 respectively. Table 5 shows the size of specimens and the test results of weight loss. As shown in the table, corrosion resistance of these materials are quite satisfactory.
Table.5 Corrosion test results

Microstructure
Microstructure observation was made at the location of pos.1 and pos.2. As shown in Figure 6, every structure is austenite and ferrite duplex structure. Secondary austenite is observed in both materials however no intermetallic phase is found.

Figure.6 Microstructure

Ferrite content
Table 6 shows the results of ferrite content measurement. AlI of them are between 35 – 55 % which is required by standards. Ferrite content of F53 is less than F51/F60.

Table.5 Ferrite Content

Hardness
Hardness measurement was made only for F53 flange because ASTM A182 requires hardness range to be maximum HB300 for F53 material. All of the results at twenty five (25) points of the radial section were between HB 238 – 260 which meet ASTM requirement. Since specifes no hardness requirement, this measurement is reference only.

Qualification of the flanges

As reported above, all the properties satisfied the requirements of standards. Based on these investigation data the flanges made of F51/F60 and F53 materials were qualified.

Marking of Welding Neck Flanges

• Flange size
• Pressure rating
• Material specification
• Tag number
• Manufacturer’s name or trademark
• Heat number or lot number
• Date of manufacture

Packing of Welding Neck Flanges

Inspection and measurement of Welding Neck Flanges

There are several factors that need to be considered when inspecting and measuring weld neck flanges, including:

To inspect and measure weld neck flanges, you will need a set of calipers or a micrometer to accurately measure the dimensions of the flange. It is also a good idea to have a torque wrench on hand to ensure that the bolts are tightened to the correct torque specification.

Weld Neck Flanges Installation Process

• Pipe Preparation: Ensure the pipe end is clean, free of debris, and has a smooth, beveled edge to facilitate a proper weld.

• Flange Alignment: Align the weld neck flange with the pipe, ensuring that the bolt holes are properly oriented and the flange face is parallel to the pipe end.

• Tack Welding: Secure the flange in place with small, temporary welds, known as tack welds. These welds maintain the flange’s alignment with the pipe during the welding process.

• Welding: Perform a full-penetration, butt-weld between the pipe and the weld neck flange, ensuring a strong, leak-free connection.

• Inspection and Testing: Inspect the weld for any defects or inconsistencies, and conduct pressure testing to verify the integrity of the connection.

Application of Welding Neck Flanges

ASME B16.5 Welding Neck Flanges are known to deliver exceptional performance and are generally developed to meet the demands. We offer a broad range of Welding Neck Flanges through a worldwide network of stock-keeping branches.

This Welding Neck Flange is used in various industries:

• Welding Neck Flanges used in Oil and Gas Pipelines;

• Welding Neck Flanges used in Chemical Industry;

• Welding Neck Flanges used in Plumbing;

• Welding Neck Flanges used in Heating;

• Weld Neck Flanges used in Water Supply Systems;

• Welding Neck Flanges used in Power Plants;

• Welding Neck Flanges used in the Paper & Pulp Industry;

• Welding Neck Flange uses in General Purpose Applications;

• Welding Neck Flanges used in Fabrication Industry;

• Welding Neck Flange uses in Food Processing Industry;

• Welding Neck Flanges Use in Structural Pipe.

Slip-On Flanges VS Weld Neck Flanges

Welding-neck flanges and weld neck flanges have some similarities and differences, as shown below:

How to purchase the correct weld neck flanges?

• Flat face (FF): This type of flange face has a flat, smooth surface that is perpendicular to the axis of the pipe. It is typically used for low-pressure applications and when the sealing is achieved by a gasket.
• Raised face (RF): This type of flange face has a raised ring on the surface that surrounds the bolt holes. The ring provides a surface for the gasket to rest on, which helps to create a better seal. It is commonly used in applications with moderate pressure.
• Ring joint face (RTJ): This type of flange face has a specially designed groove to accommodate a metallic ring gasket. The groove is cut into the surface of the flange, and the gasket sits in the groove to create a tight seal. This type of flange face is typically used in high-pressure applications.
• Tongue and groove face (T&G): This type of flange face has a raised tongue on one flange and a matching groove on the other flange. The tongue fits into the groove, creating a tight seal without the need for a gasket. This type of flange face is often used in applications where high pressure and temperature are involved.
• Male and Female Face (M&F): This type of flange face is similar to the tongue and groove face. However, it has a male and female end which creates a face to face contact between two flanges. This type of flange is mainly used for low pressure and low temperature applications.

Once you have identified the material and weld neck flange type, the next step is to determine the size and pressure class of the weld neck flange. weld neck flanges are available in various sizes and pressure ratings, and it’s crucial to select the correct size and pressure class to ensure that the flange can withstand the intended operating conditions. You should consult the system specifications and design to determine the appropriate size and pressure class.

Surface Finish

The flange face’s surface finish directly impacts the seal’s quality between the flanges. Common surface finishes include smooth, serrated, and grooved. Consult with the gasket manufacturer and consider the specific requirements of your application to select the most appropriate surface finish for your weld neck flanges.

How to select weld neck flanges manufacturer?

Choosing the right weld neck flanges manufacturer is essential to ensure you get high-quality products that meet your needs. Look for a manufacturer with quality certifications, experience, a good reputation, customization capabilities, and a competitive price. By following these tips, you will be able to find the right manufacturer for your flange needs.

Why Choose Guanxin to Be Your Weld Neck Flange Supplier?

Guanxin is a well-established and reputable manufacturer and supplier of weld neck flanges that has been providing high-quality products to customers worldwide for many years. Here are some reasons why you might choose Guanxin to be your weld neck flange supplier:

• High-quality products: Guanxin is committed to providing high-quality weld neck flanges made from the best materials and manufactured to the highest standards. The company has strict quality control procedures in place to ensure that each product meets or exceeds customer expectations.
• Competitive pricing: Guanxin offers competitive pricing on its products, which means you can get high-quality weld neck flanges at an affordable price.
• Wide range of products: Guanxin offers a wide range of weld neck flanges, including ANSI, DIN, JIS, EN, and other international standards. This means you can find the right product to meet your specific needs.
• Excellent customer service: Guanxin is committed to providing excellent customer service and support to all of its customers. The company has a team of experienced professionals who are available to answer any questions or concerns you may have.
• Fast delivery: Guanxin understands the importance of timely delivery and works hard to ensure that all orders are shipped out quickly and efficiently.

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