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Flange Facing Considerations

Flange O’Clock – Episode 3

Join our host John Barnett as he explains and demonstrates many of the different Flange flange-facing options available, including Raised Face, Flat Face,

Ring Type Joint, Small and large Male and female, and Small and large Tongue and groove. Thank you for watching and we hope you found our video helpful! If there’s anything else you’d like to know, leave a comment and we’ll get your answer ASAP!

Feel free to check out Episode 1 about the 6 most common flange types here:

You can also watch Episode 2: Pipe Flange Pressure Classes Per ASME B16.5 here:

Welcome back to Flange O’Clock.

Today, we’re going to be discussing several different flange-facing options. The face of a flange is the side opposite the hub that faces the bolted connection of the main flange flange fitting or flange valve.

The most common face is the Raised Face flange, such as the one I have here. On this Class 150 flange, we have a 1/16-inch raised face. On flanges in Class 400 and higher, the raised face is a quarter-inch tall.

For more information regarding pressure classes, please see our previous video titled “Pipe Flange Pressure Classes.”

Raised Face and Flat Face

The raised face is intended to decrease the surface area of the seal, thus concentrating the surface pressure applied when mating the flange. The result is a stronger seal.

The raised face has a machined serrated finish that will bite into the gasket whenever pressure is applied. Another option with a similar method of use is the flat face, sometimes called the full face, which has a machined face across the surface of the flange with serration going from the OD all the way to the ID of the flange.

These serrations then bite into the gasket just like they do with the raised face but, you have more surface area. The serrated face typically comes with either phonographic or concentric grooves.

Phonographic and Concentric Serrations

The phonographic groove is a continuous spiral from the outside of the face to the ID, or in the case of most blinds, to the center of the flange. I’d say think of a record but, since you’re watching this on the Internet in the 2020s you might not remember such things.

Concentric facing is sometimes required for a vacuum surface and looks similar to a bull’s-eye. To protect the serrated finish on the face of the flange, we have available face protectors like these.

Our flanges are always shipped to protect the faces through shipping but, if you’d like you can ask for plastic snapping protectors that go into the bolt holes like this and they will protect the serrations on the face from being dented or scratched. Sometimes the face is damaged in such a way that it will derate the flange so protecting the flange face is very important.

Ring Type Joint & Gaskets

There is also the ring-type joint, or RTJ, that is used when a metal-to-metal seal is required or desirable. The metal ring gasket sits inside the groove of each face and as the flanges are bolted together the ring is crushed and deformed into the flange of the groove creating a strong metal-to-metal seal. These are useful in high-temperature and high-pressure applications but also available in all pressure classes, like this 150# that takes an R-15 gasket.

Alternate Flange Facings

As we’ve seen so far the most common flange facings are designed to work with identical faces such as raised face with a raised face, RTJ with RTJ, and flat face with a flat face. Other flange-facing options are available that we refer to in the back of our catalog as “Alternate Flange Faces.”

These are tongue and groove and male and female, each of which is available in either small or large configurations. In this case, we have a small tongue with a small groove we have a small male with a small female.  Note you’ll need special gaskets in each of these cases.

Note that everything we’ve covered so far on facing has not addressed the type of flange. Most of these are available in all types. So when calling out the facing required please remember to include all other required descriptors like size, pressure class, the flange type, the schedule  (if it’s a weld neck or a socket weld) and the material of construction.

So whether you need a 1/2″ 150# Flat Face Slip On in A105, a 12″ 600# RTJ Weld Neck Extra Heavy in 316, or a 60″ 300# Raised Face Blind Series A in F11 or some oddball in Inconel 625.

We’re here to get you the flanges you need when you need them.

Call or email us today!

If you still need help deciding which is better for your project, pipeline, or job, feel free to call (281-484-8325) or  e-mail the Texas Flange sales office anytime from 8 am to 5 pm Monday through Friday.

You can also drop a quick question or inquiry into our quick contact form.

With our decades of expertise, we can help you get the flanges you need!

If you’d like to learn more about flange specifications, types, uses and more feel free to peruse our informational blog posts, free 3-D and CAD drawings, or flange charts.

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