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What Is a Cast Iron Flange?

K'Lee Banks
K'Lee Banks

A cast iron flange is one of the many types of metal flanges that are available for manufacturing and industrial purposes. Often chosen for their reliability, cast iron flanges are typically found in most standard plumbing applications. Cast iron is susceptible to rusting when exposed to moisture for long periods of time; therefore, cast iron flanges are sometimes replaced with metal flanges that have more longevity under these conditions, such as those constructed of stainless steel. As they are often mass-produced, cast iron flanges have lower production costs, which makes them a popular choice when an application allows for them. Using cast iron flanges in any flange assembly can make the task of joining two lengths of pipe much easier.

All metal flanges have certain qualities or properties that usually make one type preferable over another, depending on the application. For example, ductile iron flanges can rust over longer periods of time. Stainless steel flanges, on the other hand, do not. Another consideration, however, is that the stainless steel flange will likely cost significantly more than a cast iron flange, even if the flange sizes are the same.

Woman holding a book
Woman holding a book

The cast iron flange represents one of many types of metal flanges that are available to meet specific needs. It is usually best, however, to replace one type of metal flange with the same type. For example, if one attempts to exchange a stainless steel flange for a cast iron flange, one may discover another repair is needed sooner than desired. Some conditions will allow cast iron, but if water is part of the equation over a long period of time, then the cast iron flange may eventually fail.

There are numerous types of metal flanges to meet most any application requirement. Although generally used to join lengths of pipe, flanges are also used to seal off the end of a pipe, or to reduce the diameter of a pipe to match another smaller one. Flanges can be welded to the end of a length of pipe, or in certain applications, threaded on.

Using cast iron flanges does not require any additional skills. If one knows how to disassemble one type of metal flange assembly, a cast iron flange assembly will be no different. Standard flange sizes do not change simply because the type of metal changes. Sizes will remain the same, but the materials used will change depending on application requirements.

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