The Weld Neck Flange is easily recognizable by the hub that gradually tapers from the bolted connection to the pipe. At the Point of Weld on the Weld Neck it is supplied with a specific bore to mate with the attaching pipe or fitting. This connection is made with a full penetration butt weld, this prevents turbulence at the joint, reduces erosion and restriction to product flow. The Weld Neck Flange offers increased strength under higher pressures, subzero or elevated temperatures that cause line expansion or retraction or other variable forces. The Slip On Flange is connected to the pipe by two welds, one on the back side of the Flange and one on the inside of the Flange. The inside weld of the Flange to the pipe is recessed a minimum of the wall thickness plus 3 millimeters or 3/16&#; of an inch. This is to avoid damage to the gasket seating surface or face. Although the initial cost of a Slip On Flange is slightly less than a Weld Neck Flange, you have two welds one on the back side and one on the inside of the Flange and the added inspection of the second weld doubling weld and inspection cost. The Slip On Flange is designed to be welded to pipe then a fitting as fittings are designed for butt weld connections. The calculated strength of a Slip On Flange under internal pressure is about two thirds that of a Weld Neck Flange, and their life under fatigue is about one third that of a Weld Neck Flange.
A welding neck flange (also called a &#;weld neck flange&#;) is well recognised for its long-tapered hub, which provides mechanical strength (useful to resist &#;dishing&#; and &#;bowing&#;). Welding neck flanges are high integrity flanges and are available in all sizes, all common face types (flat, raised, RTJ), and all classes. Due to the strength of the hub and the integrity of the weld, this type of flange is well suited for elevated temperature and pressure applications.
Welding Neck Flange Cross Section
A butt weld, also known as V-weld or groove weld, provides single full weld penetration and is used to connect the welding neck flange to a pipe or fitting. The single full weld penetration makes this type of flange suitable for severe operating conditions, such as high-pressure systems, sub-zero temperatures, and elevated temperatures. Other welding neck flange benefits include:
Excellent stress-distribution along the tapered hub.
Unrestricted flow with a low pressure drop across the valve (low delta P).
High cyclical loading capability.
Causes minimal turbulence.
Low erosion rates.
Means for a direct connection to elbows, tees, or reducers.
On larger diameter flanges, there is more available space to perform non-destructive testing on the weld (difficult on some flange designs due to the location of the weld).
High resistance to bending moments due to the long hub.
Welding Neck Flange
The unrestricted flow and low turbulence characteristics of a welding neck flange are linked to the low pressure drop across the flange; this is because the flange bore is the same as the pipe bore. Erosions rates are also linked to the pressure drop across the flange, although the erosion rate depends heavily upon what is flowing through the flange.
This type of flange has one significant disadvantage compared to other flange types, it is more expensive (a deciding factor for most companies).
Non-Destructive Testing (NDT) Techniques
A phased array (ultrasonic NDT technique) flange face corrosion inspection can be conducted on welding neck flanges; the results reveal any internal damage on the sealing face.
Magnetic particle inspection (MPI), dye penetrant inspection (DPI), radiographic testing (RT) and/or ultrasonic testing (UT) can be used to prove the butt weld.
ASME Standards
The standards ASME B16.5 and ASME B31.3 specify the requirements for welding neck flange installation, maintenance, and testing.
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https://en.wikipedia.org/wiki/Weld_neck_flange
https://www.texasflange.com/weld-neck-flanges
http://www.wermac.org/flanges/flanges_welding-neck_socket-weld_lap-joint_screwed_blind.html
Have you ever thought why small components like flanges are so crucial? These are usually such small components within a large piping assembly; what role do they effectively play? Well, flanges play an essential role when it comes to pipe connections and fittings.
A weld neck flange is one of the flanges that is useful in various industrial applications, and along with slip ons and blinds, are The Most commonly selected connection.
This guide will explain the pros of weld neck flanges, which can help you make an informed decision on selecting them for your project.
Weld neck flanges are vital self-sustaining flange connections, with a sloped neck and a butt-weld end connection to weld to pipe and form one structural unit.
Their contoured design reduces the pressure on the neck and transfers it to the base, where it connects with the vessel. The production of these flanges is sometimes more expensive due to the length of the necks requiring more base material.
Weld neck flanges are useful in high-stress applications, especially for ASME Pressure Vessel applications. The internal diameter of the flange matches the inside tube or pipe, reducing friction and obstruction of flow.
These flanges are available in various materials like copper, galvanized steel, stainless, cast iron, and aluminum. There are some competitive edges when we use this flange in an assembly, as well as a few disadvantages.
Here is a list of weld neck flange benefits.
1. Superior Strength: Weld neck flanges are incredibly strong due to their welded neck design, making them ideal for high-pressure and high-temperature applications. They are often required selections over threaded or slip on styles due to their superior integrity.
2. Leak Resistance: Their precision welding ensures a tight seal, minimizing the risk of leaks and providing enhanced safety.
3. Reduced Stress Concentration: The smooth transition from the flange to the pipe reduces stress concentration, preventing cracks and failures.
4. Alignment Accuracy: Weld neck flanges facilitate precise alignment of pipes, resulting in better flow and reduced turbulence.
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5. Enhanced Durability: Given their size/shape, these flanges typically have a longer lifespan due to their resistance to wear, corrosion, and erosion.
6.Reduced Maintenance: With fewer chances of leaks and failures, maintenance costs are lower than other flange types.
7. Improved Flow Characteristics: The smooth bore of weld neck flanges reduces pressure drop and turbulence, enhancing fluid flow.
8. Easy to Align, Install, and Test: Weld neck flanges can easily align to the pipe network in which it gets installed, resulting in a more robust weld. Also, the flange design makes it very accessible when inspecting the integrity of the weld via radiography testing.
9. Smooth Flow of the Liquid: Weld neck flanges match the pipe&#;s internal diameter, allowing a smooth, high-pressure liquid flow. Also, the design assures that there is little &#;turbulence&#; within the pipe, a common reason for erosion, leading to robust, more durable pressure vessel connections.
10. Strong and Reliable: Weld neck flanges increase the pipe thickness from the weld all the way to the face of the flange. This design assures that the internally built stress by the flow of high-pressure liquid transfers to the pipe; it decreases the pressure on the flange itself.
Although weld neck flanges offer many benefits, they can have a few disadvantages when it comes to installation and maintenance, among other things:
1. Welding skill
Installing weld neck flanges is not easy; it requires specific skills like a more advanced welder. The smooth internal connection reduces the friction in the material flow.
Also, outside weld needs to match specific standards. Therefore, properly conditioned welding skills are crucial for installing these flanges, especially with ASME pressure vessel applications.
2. Leak occurrence
Along with installation techniques, experts must inspect each connection using a radiography test. Even though the connections pass the tests, sometimes there can be air pockets within the weld, which the test cannot detect.
Over time, these bubbles can develop leaks. The good news is that you can repair these leaks without replacing the whole flange.
3. In a nutshell
Over time, engineers and technicians have enhanced the installation techniques for weld neck flanges. The welding industry has already taken significant steps towards training welders to use equipment and methods in a better way and make installation less test failures and safer than ever.
If you&#;re wondering which flanges will suit your industry, we&#;re happy to assist you. Texas Flange offers a wide range of flanges, including custom ones. Feel free to reach out to us and get the right flange for your project needs!
While welding requires skill and expertise, installing weld neck flanges is straightforward if you&#;ve trained welders and the procedures are in place. The precision fit of the flange and pipe ensures alignment during welding.
Yes, weld neck flanges are available in both raised face and flat face configurations, providing flexibility in their use based on the specific requirements of the piping system.
While the initial cost of weld neck flanges may be higher due to welding requirements, their durability, and reliability often result in long-term cost savings by reducing maintenance and downtime.
One of the key advantages of using Weld Neck Flanges is that they can spread stress evenly across the joint to ensure a perfect weld. One way of doing this is by aligning the pipe and the flange properly to avoid imperfections, which may affect how these two are mechanically joined.
Nevertheless, it needs skilled laborers hence, accurate positioning during fabrication stages has to be done well so that no harm will happen to this connection. The reason why Weld Neck Flanges are preferred in industries such as oil and gas, chemical processing or power generation is their exceptional resistance to high pressures and temperatures.
A major advantage of using Weld Neck Flanges is their ability to uniformly distribute loads around joints resulting from its inclined hub shape. They are also made with smooth inner walls which facilitate easy flow through them enhancing overall system performance efficiency. Conversely, one should keep in mind that welding makes them more difficult and expensive to install than other types of flanges.
Furthermore, due to welded connections for dis-assembly purposes too much care has to be taken into account while organizing maintenance or repairs because taking them apart may not be an easy task once they have been installed together with the line. In all, companies involved in building critical infrastructure all over the world cannot do without Weld Neck Flanges since they possess rugged construction coupled with excellent performance and reliability at an affordable cost.
As far as Weld Neck Flanges (WNF) are concerned, there is a wide range of them in terms of types and materials depending on the needs of individual applications.
In matters of types there are standard orifice flanges which serve for most requirements. These have raised faces and bolt holes around the edges to attach with other flanges or components more so easily.
There exist also long welding neck flanges that have an elongated nozzle for extra reinforcement and welding room primarily used in most specialized environments.
Another type is reducing weld neck flange which connects pipes that have dissimilar diameters. Additionally, high hub welding neck flanges are taller versions of standard Weld Neck Flanges meant for use under higher pressures.
It is worth noting that carbon steel is widely used in many industries as it is strong and cheap particularly where temperatures and pressures are moderate. Another well-known alternative, stainless steel, has its corrosion resistance capabilities making it ideal for food processing plants, marine environment among others.
Next comes alloy steel which offers greater strength along with heat and corrosion resistance thus being useful specifically in oil & gas industry, chemical processing sector as well as power generation activities. Besides this there exists duplex super duplex stainless steels notable for their ability to resist corrosion while at the same time being used majorly offshore harsh marine areas.
Nickel alloys on the other hand can be used for severe conditions where high temperatures come together with corrosive substances whereas titanium suits best lightweight durability necessary applications like aerospace or chemical processes respectively.
Finally picking the appropriate version or material of WNF will depend on some factors such as operating conditions, pressure, temperature limits/requirements besides budgetary constraints with regard to achieving optimal performance safety features as well as life span of piping system.
Weld neck flanges&#; are highly resistant to high pressure and extreme temperatures, making them ideal for demanding industrial applications.
Differences in sizes between the weld neck flanges are hereunder: the outside diameter (OD), raised face diameter (RFD), inside diameter (ID), bolt circle diameter (BCD) and the flange thickness. Moreover, some other important dimensions for weld neck flanges according to ANSI B16.5 standards include; nominal pipe size, outside diameter of the flange, raised face diameter, inside diameter of the pipe used for manufacturing it, bolt circle diameter, number of bolt holes on the flange etc.
For example, a 2-inch weld neck flange might have an OD equal to 6 inches.
The inner diameter which is directly proportional to the outer dimension of the pipe is also known as ID.
RFD is defined as Raised Face Diameter which refers to the dimension across the widest point of a raised face or collar in a gasket seat area
Thicker bolt hole diameters are used for heavy loads while smaller ones are employed where load conditions are light.
Flange thickness size could be determined by various factors such as sizes and pressure rating.
These measures may be non-linear with respect to one another due to their large sizes and are intended to give a general picture.