Applications

Applications of flanges

Flanges are integral parts of many engineering and plumbing projects. In many applications, engineers need to find a way to close off a chamber or cylinder in a very secure fashion, usually because the substance inside must differ from the substance outside in composition or pressure.

They do this by fastening two pieces of metal or other material together with a circle of bolts on a lip. This “lip” is a flange.

Plumbing

You can connect two sections of metal piping by soldering or welding them together, but pipes connected in this way are very susceptible to bursting at high pressures. A way of connecting two sections of pipe more securely is by having flanged ends that you can connect with bolts. This way, even if gases or liquids build up to high pressures inside the pipe, it will often hold with no problem.

Mechanics

In order to connect two sections of a large, enclosed area, it is often best to used flanges and bolts. An example of this is the connection between the engine and the transmission in an automobile. In this case, both the engine and the transmission contain a number of moving parts that can easily get damaged if they get dust or other small objects inside of them. By connecting the outer casings of the engine and transmission in this way, engineers protect the inner workings of both.

Electronics

Flanges have a specific purpose in cameras and other electronic devices. Though flanges in such items do not usually have to sustain high pressures, they do have to hold tight so they can keep out harmful particles. These flanges are usually found connecting two different materials, such as the glass of a lens and the rest of the body of the camera.

Awwa C207 Flanges Class B Class D Class E Awwa Pipe Ring Flanges

A Ring Type Joint Flange is a type of flange that uses a metal ring that sits in a hexagonal groove as a gasket to seal the flange pair. The flanges seal when the bolts are tightened and the gasket is compressed into the groove making a metal to metal seal. An RTJ flange usually has a raised face with the groove machined into the face of the flange. The raised face doesn’t serve as a way to contain the pressure.

data wnf rjf b16.5RTJ Flanges are used for high pressure applications up to pressures as high as 15,000 psi (103 MPa). It is only furnished only on steel or alloy valve bodies and usually need to specified when ordering. The flanges usually come in blind, slip-on, threaded and weld neck.

The benefits of using an RTJ flange and ring is that the gasket is confined to a groove and has two sealing surfaces. The groove assures that the ring centers itself when the bolts are tightened. It also is self actuating meaning that the sealing pressure increases when the process pressure increases.

The disadvantages of using RTJ Flanges is that ring type joint grooves can accumulate dirt or moisture when the flange is open. Since the seal is a metal on metal connection, a small amount of damage on the narrow sealing surface(s) may lead to a leak. Additionally, the grooves and gasket must align properly in order to assemble the flange and obtain a seal. They must stay aligned throughout the operating cycle. This is important if you are flanging up to dissimilar metals like stainless steel to carbon steel flanges.

DESIGN CONSIDERATIONS

When removing the RTJ connection, the flanges must be forcibly separated to release the ring from the groove. Because of this, there needs to be sufficient access for removal of the flanges and removal of the ring.


With the wide acceptance of and significant usage of the spiral wound gasket in high pressure service, RTJ type flanges aren’t as common as raised face flanges. Consideration should be made during the design to ensure that additional rings are available when connections need to be broken.

Why raised face flange is used?

The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming (or Coining) the gasket to make intimate contact inside the grooves, creating a metal to metal seal. An RTJ flange may have a raised face with a ring groove machined into it.

RTJ flange use

Today the majority of the industry have gone away from RTJ flanges in favor of RF flanges.
It used to be common for refiners to specify RTJ’s for elevated pressure services.  Sometimes this philosophy was also applied to elevated temperature services and/or hydrogen services over a certain partial pressure.  Various combinations were also used, i.e. hydrogen service requiring Class 1500 or greater flanges.  The benefit of RTJ’s is that the gasket is confined in a groove and has two sealing surfaces.  It also tends to be self-actuating (i.e., the sealing pressure, at least on one side, tends to increase with increased service pressure). 
 Over time, most refiners modified their criteria, reducing the instances in which RTJ flanges were required.  For example, it might initially have applied to all Class 900 and greater flanges, then to Class 900 flanges over 12 inch, Class 1500 over 6 inch and then to Class 2500.
current philosophy is to call for raised face flanges with spiral wound gaskets for all services.  We have done this for more than 20 years without any problems.  Prior to making this change, we had used raised face flanges for all Class 1500 and lower services for many years, also without issues.  Recently some refiners have preferred to use Kammprofile gaskets instead of spiral wound.
The change to all raised face flanges was made after observing them perform without incident in Class 2500 service.  Many refiners had recommended this change (based upon their experiences) prior to our making it.
 Another reason for the change is the potential for crack formation at the intersection of the sides and bottom of the groove in RTJ flanges.  These cracks can propagate into the base metal.  They can be prevented by properly contouring the groove intersections, but avoiding the “problem” geometry all together was preferred.
 Ring type joint grooves may also accumulate dirt, moisture, etc when the flange is open, i.e., they are more difficult to keep clean.  A small amount of damage (including corrosion) on the narrow sealing surface(s) may lead to a leak.  Also, as the use of RTJ’s declined, warehousing (and finding) the proper gasket(s) became a more important concern.  Another factor is that the grooves and gasket must align properly in order to assemble the flange and obtain a seal.  They must stay aligned throughout the operating cycle.  The latter point becomes an issue when mating flanges are made of different materials and not providing different hardness materials for flange and ring and also thermal expansion is a concern.  The first point is an issue at the initial assembly but can be more of a concern at reassembly after service.

Furthermore in those cases where dissimilar joint materials are in contact and where the piping is 10” nominal size or larger the use of RTJ Flanges is strongly not reccomended. In fact, due to the different nature of the two materials, ring joint flanges would experience local stresses due to differential expansion that potentially could lead to ring groove cracking. There are known cases of ring joint flange failures that have led to loss of reactor containment.  

Contents

1. Introduction and general Specifications of ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges
2. ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges Warehouse
3. ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges Labelling and Wrapping
4. ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges Logistic Details
5. Reasons why you should buy ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges form Sandco Metal Industries
6. Our Best Offer on ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges
7. Price and Application of ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges
8. ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges Advantages
9. ASME/ANSI B 16.5 Ring Type Joint Flanges / RTJ Flanges sales location and global market