Understanding the Basics of Pipe Flanges

Posted on December 9, 2020 Jerold Perkins Aviation

Within the realm of piping and fluid transportation, pipe flanges serve as a useful method for connecting components to one another for establishing a system. By bolting together two flange components with a gasket in between, a variety of assemblies can be made. Second to only welding, utilizing the flange method of piping attachment is useful for the ability to separate and disassemble systems with ease, ensuring that maintenance and replacement of parts is much simpler. As such, flanges can create a more flexible approach to piping systems for an ease of access.


In general, typical pipe flanges consist of the component itself, a gasket, and bolts for attachment. Depending on the desired assembly, the materials of the flange are usually the same as the parts that they are connecting to. Across most applications, stainless steel serves as the most common form of material, though Monel, Chrome Moly, and Inconel are also frequently used. As such, choosing the correct material of pipe flanges and gaskets will depend on the needs and requirements of the assembly. By understanding the various common types of flanges that are available, finding the correct fit for a particular assembly can be made much easier.

The threaded flange, otherwise known as a screwed flange, is one in which an internal thread is present on the bore. As such, a threaded flange accommodates the attachment of a pipe or fitting through the male threading. By utilizing threading instead of welding, the threaded flange allows for easier assembly and disassembly.

For pipes that are smaller in diameter and operate within low temperature and low pressure applications, the socket-weld flange provides connection through a single multi-pass fillet weld. While such a component may remove the ease of disassembly, the socket-weld flange is quite easy to install, and avoids the various setbacks that threading faces.

For applications in which there are higher flow rates of liquids, slip-on flanges can provide an optimal solution. Also accommodating for larger pipe diameters, slip-on flanges may come in a variety of sizes. For installation, a slip-on flange requires the use of fillet welding to both sides of the flange to guarantee a robust attachment to the pipe.

With a lap joint flange, a two-piece design is present in which the attachment can be made through butt welding of the stub end. Due to its design and capabilities, the lap joint flange excels in systems that are limited in space. Additionally, the lap joint flange also allows for frequent dismantling, benefiting maintenance endeavors.

With the weld neck flange, butt welding is also used for installation. Their difference, however, lies in the fact that such pipe flanges have high integrity and performance in applications that have repeat bends. Coupled with their ability to withstand high temperatures and pressures, the weld neck flange is commonly used for process piping.

Last but not least, the blind flange is another common type of flange, typically reserved for the termination or isolation of piping systems. As a boltable blank disc, a blind flange may be installed alongside gaskets to serve as a robust seal for a piping system.

Beyond the common types of pipe flanges, many specialty designs are also utilized to accommodate diverse applications, assemblies, and environments. Whether you are in need of pipe flanges, gaskets, or other piping parts, look no further than Aerospace Exchange. As a leading online parts distributor serving many industries, we provide customers access to an unrivaled inventory containing over 2 billion new, used, and obsolete items. Get started on the parts procurement process today with a personalized quote on the items that you are interested in when you fill out and submit an Instant RFQ form as provided through our website.

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