RUBBER COATED RING TYPE JOINTS
This is an oval Ring Type Joint totally enclosed in a nitrile rubber coating. The Ring Type Joint material is usually soft iron or low carbon steel. This type of gasket has three main functions:

STYLE R AND RX WITH PTFE INSERTS
Style R and RX Ring Type Joints can also be supplied with PTFE inserts, in order to reduce turbulent flow and eliminate gasket/flange erosion. For the RX style Ring Type Joints, the insert is specially designed with radially drilled pressure passage holes so that the self energizing performance of the RX Ring Joint is not impaired. As can be seen in the sectional view, the insert is located between the inside diameter of the Ring Type Joint and the bore of the flange. On assembly, the insert is completely trapped between the make up of the flanges, filling the annular space between the flange bore and gasket.

LENS RINGS
The Lens Ring is a metallic gasket design incorporating spherical seating faces designed to suit a specific mating flange profile, providing the user with a high integrity, high pressure/ temperature metal to metal seal. Lens Ring gasket technology is covered solely by the DIN 2696 specification, however, other flange standards can be modified to accept the Lens Ring. As with all metallic gaskets, the Lens Ring material should be specified softer than the flange material, thus ensuring applied compressive load leads to the elastic/plastic deformation of the lens ring and not the flange sealing face. The distribution of high compressive loads leads to the spread of the gasket facings, ensuring over stressing of the gasket is prevented. In accordance with DIN 2696 general materials are limited to a range of specified carbon and stainless steel grades, although alternative grades are available upon request. Flexitallic requires a detailed drawing to be supplied when ordering non-standard Lens Rings.

FLEXPRO™ FACED RING TYPE JOINT
The Flexitallic style Flexpro™ faced Ring Type Joints are suitable for use in high pressure applications where API or ASME ring groove style flanges are to be sealed. The Ring Type Joint metallurgy is generally specified by the customer to match the flange material and to be suitable for the application media. The relevant 23° angled sealing faces of the Ring Type Joint are machined with concentric serrations to provide a low stress sealing face to which a soft sealing material is applied. This low stress sealing capability avoids the need to deform the metal of the Ring Type Joint. Standard Ring Type Joints can only be used once, however, after careful removal of the used soft facing material and inspection confirming the integrity and quality of the metal Ring Type Joint, the facing material is replaced and the Flexpro™ faced Ring Type Joint re-used.
SOFT SEALING MATERIALS
The soft materials that are applied to the sealing faces of the Flexpro™ (kammprofile) faced Ring Type Joints are Flexicarb® or Thermiculite® (vermiculite). Maximum operating temperatures are dependent upon the metallurgy and the facing material selected:
Flexicarb® (Graphite) 450°C (842°F)
Thermiculite® 980°C (1800°F)
COMPLIANCE
The underlying metallic Ring Type Joint conforms to the dimensional requirements of the relevant API or ASME standard. NACE compliant material can be supplied upon request.

TRANSITION RING TYPE JOINTS
These are combination rings which consist of two different sizes having the same pitch circle diameter. They are used for sealing Ring Type Joint flanges where the mating flanges have different ring groove geometry. Transition Ring Type Joints can be manufactured from standard materials, as well as exotic alloys. Transition Ring Type Joints are available with either oval or octagonal facings and are not encompassed within the API or ASME specifications.
BLIND AND ORIFICE RING TYPE JOINTS
Blind Ring Type Joints can be manufactured to blank off flanges and pipework. They consist of standard Ring Type Joints with integral solid metal centers. The height of the standard Ring Type Joint section of the gasket is increased to allow for the solid center to fit in between the two flanges and permit the sealing faces to locate correctly inside the ring grooves. Orifice Ring Type Joints are used for either restricting and / or measuring fluid flow and are sized to customer requirements. As with the Blind Ring Type Joints the height of the Ring Type Joint section is increased to allow for the thickness of the orifice plate. Blind Ring Type Joints can be supplied in all standard and exotic materials. Unless instructed otherwise, Blind / Blank thicknesses are calculated in accordance with ASME B31.3. For further information on specialized Ring Type Joint products, please contact MUNACO'S Applications Engineering Department.

SUBSEA GASKETS
Flexitallic is able to provide specialist machined seals that are designed for use in subsea wellhead, mudline and tree equipment within the scope of API 17D. The Offshore Oil and Gas industry imposes demanding performance requirements on gasketed bolted connections. High pressures and temperatures along with the ever present possibility of corrosion and the need for sub-sea assembly, make the correct gasket style and material selection of crucial importance. To distinguish subsea Ring Type Joints from those used topside, the suffix “S” is applied to indicate the additional pressure passage hole in the ring cross-section. This additional requirement is to prevent pressure lock occurring when connections are assembled underwater. API 17D provides two drilling options for the pressure passage holes, option A and option B as shown.
Other than the addition of the pressure passage holes, all other physical aspects of the API 17D SBX Ring Type Joint is the same as the API 6A BX Ring Type Joint. It should be noted that API 17D no longer supports the use of SRX ring type joints (API 6A RX Ring Type Joints with subsea drillings), however, when opening flanges on existing equipment replacement SRX Ring Type Joints may be used.