Wellhead Flanges: Ring Type Joint vs. Raised Face – What’s the Difference?

When selecting flanges for wellhead and high-pressure oilfield applications, one of the most important decisions is the choice of flange facing: Ring Type Joint (RTJ) or Raised Face (RF). Both provide reliable sealing in the right application, but they work differently, perform differently under pressure, and are not interchangeable. Understanding the distinction matters whether you are ordering replacement parts, performing a wellhead installation, or troubleshooting a leak.

Raised Face Flanges

A raised face (RF) flange has a slightly elevated sealing surface in the center of the flange face. When bolted together with a mating RF flange, the raised faces compress a flat or spiral wound gasket between them, creating the seal. The raised face directs bolt load to a smaller sealing area, improving gasket stress and sealing performance compared to a full-face design.

Raised face flanges are widely used in general industrial piping (ANSI/ASME B16.5) and in lower-pressure oilfield applications. They are easy to inspect visually, relatively forgiving of minor surface imperfections, and compatible with a wide range of gasket materials including spiral wound, corrugated metal, and compressed fiber types.

The practical limitation of raised face flanges is that they are not ideal for very high pressures or where leakage tolerance is extremely low. At high pressure, the compressible gasket may relax over time, requiring re-torquing of bolts.

Ring Type Joint Flanges

Ring Type Joint (RTJ) flanges use an entirely different sealing mechanism. Instead of a flat gasket, an RTJ joint uses a solid metal ring gasket — typically oval or octagonal in cross-section — that seats in a precision-machined groove cut into both flange faces. When the flanges are bolted together, the ring gasket deforms slightly and wedges tightly into the grooves, creating a highly reliable metal-to-metal seal.

RTJ flanges are the standard for API 6A wellhead equipment and high-pressure oilfield applications. They offer several advantages: the metal-to-metal seal does not relax over time like a compressible gasket, they maintain integrity at working pressures up to 20,000 psi, they perform well at elevated temperatures, and they are far less susceptible to fugitive emissions than raised face designs under cycling pressure conditions.

The trade-off is that RTJ flanges require precise machining tolerances in the ring grooves, and the ring gaskets must be replaced every time the joint is broken — they cannot be reused. Ring gaskets are available in multiple material grades including soft iron, low-carbon steel, stainless steel, and Inconel for sour or corrosive service environments.

Choosing Between RTJ and RF

For wellhead assemblies, Christmas trees, and any API 6A equipment above 2,000 psi, RTJ flanges are almost always specified. For lower-pressure utility piping, instrumentation connections, or non-critical applications, raised face flanges may be appropriate and more economical.

CRC Wellhead machines RTJ flanges, companion flanges, weld neck flanges, and custom flange configurations from our Edmonton facility. All wellhead-rated components are machined to API 6A dimensional and surface finish requirements. Contact us to discuss your specific flange requirements.