What Does a Pipe Flange Do in Plumbing?
If you've got customers asking you why you need a pipe flange in a particular location, you might be wondering what the right answers are to their questions. Fortunately, we've collected the details so that you don't need to - you can just point them to this post. In this post, we'll talk about what a pipe flange is, the different types, where they tend to be located, whether they're considered fittings, and how to select the right pipe flange for your application.
What is a Pipe Flange?
Used to connect pipe sections, flange faces bolt together to create a strong, watertight connection that will hold up well under high temperature or high pressure applications. It creates a much stronger joint than simply using a coupler or other pipe fittings to connect two pieces of threaded pipe, such as fitted iron pipe systems.
However, there is a wide range of different flange types, designed to meet a range of disparate plumbing standard sections, such as ASME B16.47 or ASME B16.5. One common feature is bolt holes in the flange facing, which allow the flange to be securely fastened to the surrounding material. In the next section, we'll discuss different types of pipe flanges that you may encounter. Pipe flanges also come in several alloys some of which include: stainless steel, brass, chrome-plated brass, copper & carbon.
What Are the Different Pipe Flange Types?
- Weld Neck Flange - As the most commonly-used flange in process piping, a weld neck flange provides the highest joint integrity, because the butt weld that is created with the piece protruding from the raised face provides a strong bond. However, it can be bulky and cumbersome compared to other flange types, but is also available as a long welding neck flange.
- Slip On Flange - A slip on flange matches the outer diameter of the pipe, with two locations for fillet welding to create a strong bond. With a moderate cost, it's typically used for low-pressure and temperature applications.
- Ductile Iron Backup Flange - Often used in high pressure settings, typically between 150 and 250 PSI, a ductile iron backup flange is a relatively simple flange. It features a flat flange facing paired with a beveled edge at the center hole.
- Threaded Flange - Typically used in utilities as well as in lower temperature and pressure applications for air and water, a threaded flange has a National Pipe Thread female connection and is available in thread sizes up to 4", providing a relatively inexpensive option for a number of situations.
- Socket Weld Flange - Also used in lower temperature and pressure ranges, the socket weld flange has a stopping point, from which the pipe is pulled back slightly to allow for expansion. The pipe can then be welded around its circumference to the face of the flange.
- Lap Joint Flange - If tight spaces and an expectation of frequent dismantling is a possible issue, a lap joint flange is a decent option. Consisting of two separate pieces, a ring with bolt holes and a stub that can be welded to the pipe a short distance from the ring, the butt weld created is stronger, while the stub allows the pipe to be turned while welding.
- Blind Flange - Sometimes used as manhole covers for vessels, a blind flange has no hole for air or gas to pass through. It's also commonly used to end runs of pipe, effectively isolating the run from other systems.
- Swivel Flange - Designed to speed up installation, a swivel flange makes it easy to align bolt holes on a pair of flanges. Because the flange is able to swivel around the circumference of the pipe, it can easily be moved to match a welded flange's bolt positioning.
- Expanding Flange - When a pipe needs to change to a larger size, an expanding flange provides an effective way of managing the change. It features a widening stub that the larger pipe can be joined to, making it a popular choice for retrofit projects.
- Reducing Flange - When there needs to be a change in the side of the pipe to a smaller pipe, a reducing flange has a tapered raised face for a butt weld. Providing an economical way to reduce pipe size at a particular point, they're used in a range of applications.
- Nipoflange/Weldoflange/Elboflange/Latroflange - Most commonly used in high-pressure situations, these types of specialty flanges create a unique nipple that protrudes markedly from the flange facing. Its installation requires fewer welds, while still maintaining superior strength.
- Plate Flange - An economical alternative to heavier ANSI flanges. Plate flanges are suitable for low pressure, less critical applications. They have a serrated surface to enhance sealing properties. There are several types of plate flanges: blind, tube OD slip-on, IPS slip-on bevel x square and IPS slip-on square x square.
Where are Pipe Flanges Located?
Generally speaking, a pipe flange is located at points where regular disassembly, maintenance, or cleaning will be taking place. This can include making it possible to bolt pipe systems directly to equipment, fittings, or other features quickly, easily, and securely.
Are Pipe Flanges Considered Fittings?
Pipe flanges are considered a very popular type of fitting in plumbing systems, and are often used when pipes are used for non-plumbing systems as well, such as railings, racks, and similar applications. However, they often provide an additional level of security to the fitting, because the bolt holes allow the fitting to be secured to the surrounding structure.
How Do I Choose the Right Pipe Flange?
Pipe fittings will vary based on your application. However, by having a better grasp of how pipe flanges work, you'll be able to answer your customers' questions much more easily, improving their confidence in your ability to do the job they've hired you for. If you're looking for expert advice, contact Merit today for more details.
STILL HAVE QUESTIONS?
SOURCES INCLUDE:
https://hardhatengineer.com/types-flanges-used-piping
https://www.unifiedalloys.com/blog/flanges-101
https://www.apiint.com/resource-center/introduction-to-flanges
https://www.punchlistzero.com/swivel-flange
