Flange Versus Threaded Connections

Posted: 4/26/2019

The dictionary definition of a pump makes it sound like a relatively simple instrument. For instance, Merriam-Webster states that a pump is “a device that raises, transfers, deliver, or compresses fluids or that attenuates gases especially by suction or pressure or both.” But dealing with industrial pump applications where the materials involved can be exotic or hazardous leads to numerous complications, complications where technical expertise becomes paramount.

What kind of material should the pump be constructed of? Should it use a particular kind of motor? Will traditional mechanical seals pose a problem with the specific type of material the pump will move? March Pumps has over 60 years of experience in dealing with these sorts of questions — including the importance of choosing between flanges and threaded connections.

What Is a Flange Connection?

At its most basic level, a flange connection involves joining two pieces of material together by means of an internal or external lip. A gasket gets fitted between that pair of pieces to prevent any leakage. Then installers generally use bolts to seal them tight. (Some applications will weld the pieces together rather than employ bolts.) Flanges come in a variety of styles, everything from slip-on flanges and lap-joint flanges to weld-neck flanges and socket-weld flanges.

Though this wide variety of flanges may seem confusing at first, know that they also offer the widest array of application options. Flange connections can work well with multiple pipe sizes, open or constricted areas, jobs requiring high joint integrity, and with caustic or hazardous liquids or gasses. End users may also install flanges made from standard materials (e.g., stainless steel, carbon steel) or exotic materials designed for special jobs.

What Is a Threaded Connection?

Threaded connections are almost the polar opposite of flange connections. Rather than fitting pieces together using multiple parts, threaded connections are rimmed with matching grooves, one on the outside of a piece and the other on the inside. Assembly is simple, because the sections simply screw together.

These grooved connections provide a number of advantages and disadvantages when compared with flanges. For one thing, they often tolerate pump vibrations better. Since they don’t use bolts, their connections will never need retightening. However, few threaded connections can tolerate high-pressure or high-temperature applications. And then there’s another matter where these two most basic types of connections differ: price.

The Price Difference Between Flange and Threaded Connections

Overall, threaded connections generally cost significantly less than flange connections. This mostly owes to the multiple parts and configurations of flanges. Of course, the relative cheapness of grooved parts is balanced by their operational inflexibility. There’s a reason why threads typically only appear in various low-pressure utility applications.

How Can March Pump Help Me Find the Best Connection?

The originator of the centrifugal sealless magnetic drive pump, March Pumps has worked across industries since 1954. Companies have used our pumps for chemical transfers, desalination, bio-fuel transfers, battery manufacturing, carbon arc furnace cooling, and many more applications. We strive to modify our pumps to fit every customer’s unique situation. Call (847) 725-0580 or contact us today so that we can learn more about your application.

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