Sealing Shielding

Use a Metal Seal for Those High Temperature or High Pressure Situations!

Use a metal seal for those high temperature or high pressure situations, metal seal feaParker Hannifin Engineered Materials Group has developed a wide variety of metal seals which can be formed or machined. A metal seal is a highly engineered sealing solution which provides elastic recovery or spring back to maintain good sealing, despite separation of mating surfaces due to effects of thermal cycling, flange rotation, applied mechanical or hydrostatic loads or creep. 

Why use a metal seal?

A metal seal is used when the application conditions are outside the specification limits of a polymer. For example, when:

Temperature is too hot or too cold & pressure is too high or there is a vacuum.

Metal Seals are primarily used in static applications for temperatures as high as 1000°C/1832°F and pressures as high as 6825 bar/99000 psi for select applications. At low cryogenic temperatures and low pressures, such as vacuum seal applications, metal seals are far better than polymers since they do not become brittle and lose elasticity. Metal seals also have a low leakage rate down to 1 x 10-12 cc/sec per mm circumference which in comparison to high load O-rings is almost 100x better. 

Use a metal seal for those high temperature or high pressure situations, maximum recommended temperature graphUse a metal seal for those high temperature or high pressure situations, yield strength of high temperature seal materials

Medium is corrosive and seal longevity is needed.

Unlike elastomer seals, metal seals are very highly resilient to corrosive chemicals and even intense levels of radiation. With this resilience coupled with the right material selection/coating for an application, a metal seal can be a very durable seal performing dependably year after year.

Parker has a variety of in-house developed coatings which are used based on the application conditions and base material. The chart on page D-59 of the Metal Seal Design Guide (shown below) shows examples of some of the coatings based on the base material.

Use a metal seal for those high temperature or high pressure situations

What X-sections can be made?

Metal seal x-sections can vary from a solid O to a Hollow O and from a C Ring to an E Ring depending on the application load and allowable leakage rate as shown in the figure below. Each x-section has benefits based on the application use and cost as indicated in the chart below.

Use a metal seal for those high temperature or high pressure situations, load leakage spectrumUse a metal seal for those high temperature or high pressure situations, seal type chart

Page A-10 of the Metal Seal Design Guide (shown below) shows some common applications in the industry and the type of metal seal used in those applications. These are examples of applications where the application conditions exceed beyond what an elastomer is capable of handling.

Use a metal seal for those high temperature or high pressure situations

Importance of surface finish for metal seal applications

One of the most important and critical aspects of using a metal seal is surface finish of the mating hardware. The required surface finish co-relates to the seal free height as shown in the chart below. Since metals don’t compress or are not as elastic as some of the elastomers, it is very important to have a tighter surface finish. Most of the metal seal applications require surface finish of 32 u inch RA or better. Anything over 32 u in RA will not be bubble tight sealing (leakage rate of 1x10^4 cc/sec) which could be okay for certain applications.

Use a metal seal for those high temperature or high pressure situations, surface finish

In certain applications, higher surface finish can be negated with the help of coating applied to the metal seal. The picture below shows how coating helps navigate through the peaks and valleys of the hardware surface hence creating sealing.

use a metal seal for those high temperature or high pressure situations, surface area image

Benefits of metal seals:

  • Independent optimization of functional components means each discrete function including load, spring back and outer sealing layer ductility/hardness can be optimized to ensure highest seal performance in every situation.

  • Directly bonded electroplating onto the load bearing substrate eliminates unnecessary parts and failure modes.

  • Pressure energization uses internal hydrostatic pressures beneficially to supplement the self-energization forces from the tubing, jacket or spring. This becomes particularly helpful at high pressures over 3,000 psi (21 MPa) enabling metal seals to seal at 25,000 psi (170 MPa) and beyond, without risk of blow-by during proof or burst testing.

  • Total metal seal service covers custom and standard sized seals from 0.250" to 300" (6 mm to 7,60 m), including circular and non-circular shapes. We also offer the complete range of MS metal O-ring sizes, all AS1895 E-ring sizes, and the fastest delivery of C-rings from our preferred size list.

  • Rapid response and JIT (just-in-time) deliveries are assured due to design, testing and all manufacturing processes (including roll and die-forming, machining, welding, heat-treatment, electroplating) being performed within our own facilities. 

 

Download the Metal Seal Design Guide.

 

For additional information on metal seals, please contact our engineers or visit our website

 

This blog was contributed by:

Use a metal seal for those high temperature or high pressure situations, Vivek Sarasam

 

 

Vivek Sarasam, heavy duty mobile Sr. application engineer

 

 

 

 

Use a metal seal for those high temperature or high pressure situations, Jeffrey Labonte

 

 

Jeffrey Labonte, market manager

 

 

 

 

Related content:

High Performance Seals for Extreme Aerospace Environments 

O-Ring Sealing for Maximum Service Life in Aggressive HTS Turbine Oils

New Low-Temperature Compound Improves Jet Engine HTS Oil Sealing Performance

Categories
Recent Posts by Author

How to Determine the Ideal Metal Seal Part Number for an Application

Parker's metal seals are used in the most extreme environments that demand extreme temperature and pressure solutions. Metal seal technology is used in cryogenic, high temperature, hard vacuum, high...

Protect Your Seal Aftermarket with Part Identification Technologies

Parker is revolutionizing part identification technology with a multitude of options. Customers are able to benefit from various identification methods such as non-permanent and permanent...

Top Three Design Tips for Corrosion Resistant EMI Protection

Every design engineer should know that an EMI gasket must be installed between mating flanges to prevent electromagnetic radiation (EMI) from entering or leaving an electronic enclosure. But what if...
Comments

Comments for Use a Metal Seal for Those High Temperature or High Pressure Situations!


Please note that, in an effort to combat spam, comments with hyperlinks will not be published.

Leave a comment





Captcha