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METAL SEALS

Resilient Metal Seals – assured leak prevention for extreme conditions.

   

Our Resilient Metal Seals are designed to avoid leakage problems even at extreme temperatures and pressures, and in harsh chemical environments. Their gas-tight and fluid-tight sealing has been developed primarily – but not exclusively – for automotive power systems in medium- and heavy-duty vehicles. These include internal combustion engine (ICE) units fueled by diesel, other liquid fuels and hydrogen (H2ICE), as well as hydrogen fuel cell electric vehicle (FCEV) applications.

 

 

    
 

  Extreme resilience.

                                                                                                                                                                                                                                                                                                    

extreme temperatures	high pressures	ultra-high vacuums	harsh chemicals
up to +900°C down to -270°C	up to 75,000 psi (5,000 bar)	down to  10-12 mbar	including hydrogen, grease and residues from diesel exhaust

Enhanced system performance.

By minimizing leakage, and hence increasing power and efficiency, they improve the performance of both existing and developing fueled systems. This enhancement is welcomed by OEMs, Tier 1 suppliers and tuning kit providers. It allows systems to be pushed to new levels, without fear of the increasingly demanding conditions this creates.

A perfect and permanent fit.

Essentially, a metal seal has the properties of a spring, holding a continuous line of contact with the cavity to prevent or restrict leakage. Under a sufficient seal contact load, it deforms to conform with the shape of the contacting surface. 
Importantly, metal seals are less flexible than polymer alternatives. In most cases, the metal seal undergoes plastic as well as elastic deformation – ultimately becoming permanently reshaped to fit tightly against the sealed assembly. This is the reason why metal seals are not reusable. Once a sealed joint has been disconnected, its seal must be replaced with a new one.

Static and dynamic possibilities.

In most applications, Resilient Metal Seals are static – except perhaps for a little movement due to vibration. When we speak of a dynamic metal seal application, we are usually talking about slow and limited motion. Typically, this might mean:

• Thermal expansion – up to 0.250” (6.35 mm) of linear motion
• Movement due to mechanical clearances – 0.008-0.050” (0.203-1.27 mm)
• Movement due to pressure in the system – 0.008-0.050” (0.203-1.27 mm)
• Slow or limited rotation – quarter turns, fewer than 100x within system’s life
• Limited mating/demating cycles – fewer than 200x within system’s life

Metal seals with relatively large amounts of movement – 0.100” (2.54 mm) or more – tend to be regarded as ‘flow restrictors’ rather than true seals. However, we will be happy to work with you to create much more dynamic metal seals, with extremely low leakage, if your application requires them.
 

Key factors in leak prevention addressed.

Resilient Metal Seals can be broadly divided into two types: face seals and radial (axial) seals. Face seals generate a seal contact load by being compressed. Radial seals generate their load through interference between the contacting surfaces of the bore and shaft. In each case, the seal contact load results in deformations of the seal or its plating which enable it to fill any imperfections in the mating hardware.

The metal seal’s effectiveness in preventing leakage depends on factors including:

•    Size of the contact load
•    Quality of the seal’s surface finish
•    Quality of the cavity’s surface finish
•    Degree of conformity of the seal contact line to the cavity surface
•    Choice of plating material
 

Customised and tested for complete confidence.

At Saint-Gobain, we can vary the factors above, and other parameters, to achieve the best result for you. We offer a range of Resilient Metal Seal types, shapes and structures to suit the nature of the application and the conditions faced. As with any Saint-Gobain product, our design engineers will co-operate with you to develop a tailored solution meeting your precise needs. They draw upon deep technological experience in fields such as aviation, space and energy, as well as automotive engineering. 
The seal’s size, shape and other characteristics will be optimized for your use, and it will be produced with tight tolerances. Crucially, our simulation programs and testing facilities will ensure full confidence in its behavior under real-life conditions.

Ready for the harshest applications.

Our Resilient Metal Seals were initially developed for internal combustion engine vehicle (ICE) and hydrogen mobility applications, but their properties offer other great opportunities both within and beyond the automotive sector. Examples include:
•    Fueling noses (diesel and gas)
•    CO2 compressors
•    Robotics
•    Hydrogen tanks
•    Valves

The key automotive applications of our Resilient Metal Seals, relating to medium-duty and heavy-duty vehicles, are:

exhaust manifold	turbocharger and exhaust manifold interfaces	butterfly and wastegate valves incl. EGR* valves	bellows replacement
Challenge: hot exhaust gas temperatures; thermal movement	Challenge: non-uniform joint separation	Challenge:  extreme temperatures; thermal movement	Challenge: high cost of welded bellows; thermal movement
Solution: external dynamic resilient metal lip seals	Solution: metal turbo seal (internal pressure type) with or without retainer plate	Solution: axial V-seal	Solution: assembly including two external dynamic resilient metal lip seals and a machined tube

Flexible production options.

The base materials for our Resilient Metal Seals are usually high-temperature metals like INCONEL 718 steel and stainless steel. Optional plating with gold, silver or other coatings can be applied to adjust seal properties as required for specific applications. Heat treatment increases the seals’ strength and durability.
Most of our metal seals are produced by die-forming (stamping) or roll-forming processes. We can supply any quantity, however large or small. Depending on the volume needed, and the cost considerations, we manufacture them on manual or fully automated lines. 

Need further information? Please download the document below or contact our experts directly.

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