Within piping systems, valves, and vessels, it is critical that you choose the most appropriate flange, as these components affect safety, efficiency, and cost.
Two of the most common flange face types include raised face and ring type joint flanges. These two flanges share a common purpose: to prevent leaks from occurring, however, they also have varying differences, specifically in how they seal.
For example, a raised face (RF) seals with a flat or semi-metallic gasket compressed on the raised area, and a ring type joint (RTJ) face has a machined groove that seats a solid metal ring, providing a robust metal to metal seal.
At SSP, we specialise in a range of flanges suitable for various applications, as well as provide high-quality gaskets, including ring type joint gaskets, and isolation kits.
In this post, we look at ring type joint vs raised face in more detail, outlining the advantages and disadvantages of each.
What is a raised face (RF) flange?
A raised face (RF) flange seals with a flat or semi-metallic gasket compressed on the raised area.
Due to the raised gasket surface above the bolting circle, it concentrates the load on a smaller area.
This type of flange is most common in general processes and applications and is especially useful when you require better separation between the two flanges being joined.
Construction: the design of this flange places pressure on a small gasket area helping the joint handle pressure containment better.
Gaskets used: a wide range of soft metallic gaskets can be used with an RF flange, such as spiral wound gaskets and flat ring sheet gaskets.
Pressure and temperature: note: diameter and pressure are defined by pressure class and diameter.
Typical service: typically used within the oil and gas sector and chemical engineering industries.
What is a ring type joint (RTJ) flange?
A ring type joint flange is most commonly used in applications and systems that operate in high temperature or high pressure environments. These are typically Class 600 or more (reaching 900 in some instances) or where temperatures can surpass 427 degrees Celsius.
These machine-grooved flanges, seating a solid metal ring, provide a metal-to-metal seal, where a metallic gasket is fitted into the grooves and compressed to form a tight seal.
The RTJ flange design is oval or octagonal rings to ASME B16.20 standard. This particular type of flange is a lot stronger than RF flanges, withstanding high heat, pressure, and corrosion.
In addition, once compressed, it will also be resistant to movement and vibrations; however, it’s important to note that you do have a reduced range of gasket options which would be suitable for use.
Ring type joint vs raised face at a glance
We’ve highlighted some of the key differences between RTJ and RF flanges in the table below.
RTJ vs RF flange
| Attribute | Raised face (RF) | Ring type joint (RTJ) |
| Flange face | Raised gasket surface above the bolting circle face. | Machined groove that seats a metal ring |
| Seal mechanism | Flat or semi-metallic gasket compressed on the raised face, placing more pressure on a smaller gasket area, increasing the pressure capability of the area. | Solid metal ring compressed into the groove (metal-to-metal), compressing the gasket into the grooves, deforming the gasket so that it makes contact to provide a tight seal. |
| Gasket used | Semi metallic or non-metallic gaskets such as spiral wound, kammprofile, flat sheet or full face | Oval or octagonal solid metal ring (RTJ gasket). (Note: RTJ have three main ring type joint groups; R, RX, and BX) |
| Pressure / temperature | Low to moderate-high; general process | High; typically, Class 600 and above, or over about 427 degrees Celsius |
| Standard | ASME B16.5 (raised face facing) | ASME B16.5 (RTJ groove); rings to ASME B16.20 |
| Cost / installation | Lower cost, easier to install and replace | Higher cost, precise machining, single-use ring |
| Typical service | Water treatment, power, HVAC, general refining | Wellheads, high-pressure oil and gas, hazardous media |
| Interchangeable? | No. An RF gasket cannot seal an RTJ groove, and vice versa. Mixing causes leaks and damage. |
Which flange face should you choose?
When choosing between RF vs RTJ, it’s important to bear in mind the pressure class of the application, temperature, media criticality, and cost, all vital areas when ensuring system integrity, compliance, and efficiency.
For example, ring-type joint flanges use a metal gasket to provide a tight seal, offering you superior sealing performance. However, raised face flanges use soft metallic seals that offer more versatility and are more cost-effective.
Critical safety point: It’s essential to note that both RTJ and RF flanges are NOT interchangeable, and mixing of the two components will cause leaks or damage to the application.
How SSP can help
Understanding the key differences between ring type joint flange vs raised face flange is key in ensuring you choose the right component to meet your application’s requirements.
The good news is that at SSP we supply all RTJ rings and the full RF gasket range, which you can view across our product pages, or to speak to a member of our team about your specific requirements, contact us today.
Call 01535 274 776 for further information or a quote today.
FAQ section
Q1. What is the difference between a ring type joint and a raised face flange?
They are two flange face types. A raised face seals with a gasket compressed on a raised surface, while a ring type joint has a machined groove that seats a solid metal ring for a metal-to-metal seal.
RF is a flange whose sealing surface is above the bolting circular face, whereas an RTJ flange involves a precision-machined groove that seats a metallic gasket to form a high-integrity seal.
Q2. When should you use an RTJ flange instead of an RF flange?
Use RTJ for high pressure and temperature, typically Class 600 and above or over about 427 degrees Celsius, and for hazardous or critical service. RF suits general process applications at lower to moderate pressures.
Q3. Can you use an RF gasket on an RTJ flange?
No. The sealing surfaces are different, so an RF gasket will not seal an RTJ groove, and mixing the two causes leaks and can damage the flanges.
Q4. What gasket does a raised face flange use?
A range, including spiral wound, Kammprofile and flat sheet gaskets, selected for the pressure, temperature and media.
Q5. What standards apply?
Flange facings follow ASME B16.5, and RTJ metal rings are made to ASME B16.20.
