You may have heard that a hidden connection is stronger than an obvious one. In the world of sealing technology, solutions are often hidden within complex systems. Part of the most important components of any system, machine or device, seals are key in securing the function of many applications and to prevent leaks. Can you imagine what applications contain seals? Almost everything you use, interact with or see in your daily life needs seals to work: a dishwasher, a dryer, a car, an airplane, portable healthcare devices, and satellites. Without proper seals, systems could become completely useless or even have a critical failure.
There are different types of seals and different types of sealing environments. Omniseal Solutions™ designs and manufacturers polymer spring-energized and rotary lip seals that handle high pressure sealing and challenging conditions. In 2019, the business acquired American Seal & Engineering, which added high-performance metal sealing solutions to their global portfolio. With the recent acquisition of HTMS (High Tech Metal Seals) this year, Omniseal Solutions™ reinforces their metal sealing presence in the space and nuclear industries and added several decades of experience, essentially expanding their world of sealing technologies. Founded in 1999 by a group of sealing specialists and based in Mechelen, Belgium, Saint-Gobain HTMS’ resilient metal seals are most valuable where standard seals cannot handle extreme temperatures, pressures or media.
Metal Seals: Why Are These Solutions So Solid?
Metal seals are quite diverse and used in multiple industries. They are best suited for:
- Energy and power generation (steam and gas turbines)
- Industrial (valves, pumps and lasers)
- Oil and gas (high temperature and high pressure valves, compressors and couplings in upstream)
- Nuclear (reactors, pumps and valves, nuclear spent fuel casks)
- Aerospace (valves, thrusters and cryogenic engines)
- Semiconductors (tin shooters and catchers)
- Science and research / fusion (vacuum vessels, reactors, connectors)
- Automotive (exhaust, motor, turbo compressor)
There is a demand in Europe for metal seals in aerospace. According to Fior Markets, “The aerospace sector [is] anticipated to grow at the CAGR of 5.62% over the forecast period, mainly due to rising usage of metal seals in various aerospace applications such as engine system, airframe, flight control & hydraulic system, and landing gear system.” Even though this trend has most likely changed due to current circumstances, a push for more efficient technologies is ongoing and will ultimately benefit this market.
Some sectors may emerge as needing this type of metal sealing technology due to global demand, usage or other factors: life science; nuclear and science research; and commercialized space. In space, metal seals as well as polymer seals are used in various parts of a satellite. Fusion will come more and more in the future picture if projects succeed in countries pushing for clean energy.
To supply the right solution for their customers, Saint-Gobain HTMS provides several metal seal designs:
- Metal O-Seal
- Spring-energized metal O-seal
- Metal C-Seal
- Spring energized C-seal
- Spring-energized aluminum C-Seal
- Metal Oysterseal®
- Metal Commaseal®
Most of the seals are custom designed to precisely fit the customer’s application. Saint-Gobain HTMS’ solutions come in many shapes, sizes and materials. The main differences in the seal types are the amount of spring back, sealing load, seating stress, sealing surface and leak tightness.
Why are metal seals selected versus other solutions like PTFE seals? Metal seals are very often selected when PTFE seals have reached their limit in terms of temperature, pressure, chemical compatibility or required leakage rate in cryogenic conditions. PTFE seals are often limited to the permeability of the PTFE in cryogenic conditions, while metal seals have no issue with permeability (aside from PTFE coating).
Custom Solution + Co-Development = Successful Application
Making sure to select the right seal is key but also how the solution is developed. Saint-Gobain HTMS co-develops with the customer; in fact, they created selection wheels (Fig. 1) for customers to review first to understand how their applications could work before contacting HTMS. It is a proactive way to provide a mutual learning process and make customers understand why they need a specific seal.
In order to design an effective metal sealing solution, you must consider surface finish as well as sealing load, flange deflection and important variables in the design/development process of the seals. Saint-Gobain HTMS takes time and care to determine limiting factors in the application, which could be bolt configuration (low compression force), flange materials (soft material need appropriate seal designs), customer capabilities to achieve desired roughness properties, seal mounting (sometimes upside down); and then designs the seal accordingly.
Fig. 1: Saint-Gobain HTMS’ Customer Selection Wheels
When Saint-Gobain HTMS works with a customer, they are fully engaged with the customer from start to finish. Their focus is to create mutual trust and develop a solution together with the customer. Saint-Gobain HTMS’ most important values are: To be responsive, agile and flexible; to maintain short lead time; to listen to customer needs; to design engineer and provide custom solutions; to be reliable; and to always deliver quality.
Customer success stories have been a result of integrating processes into existing system for better control, developing alternative solutions when existing standard ones fail, and reducing downtime for customers who are using existing ineffective solutions.
They are known for their quick response, delivering within two to three days when customers needed a solution urgently. A specific success involved remanufacturing one seal on the last day before their annual holiday period and bringing the seal themselves on Christmas evening to the CERN in Switzerland. Another success was manufacturing seals in two days for a F1 race in Barcelona.
The Outside is Just As Important: Metal Seal Platings, Coatings, and Liners
The inner design of the metal is critical but the outside is just as important. Metal seal platings, coatings and liners are unique features in sealing technology. The additional soft layer improves the leak rate. With three different types of soft layers on top of a metal jacket, Saint-Gobain HTMS is able to find a perfect solution for a vast majority of demanding applications. All three provide the same functionality to fill the roughness of the counter flange and improve sealing performance. The softer the plating, the better it can cover surface irregularities in the hardware. In general, a metal seal goes hand in hand with high demands on the surface quality of the customer’s hardware. For coatings, Saint-Gobain HTMS usually applies PTFE, while plated seals use silver, gold, tin, copper and nickel as a top layer. For jacketed seals, they use aluminium lining.
Looking Beyond: Future Metal Sealing Technology
The overall drive to develop and use more efficient applications translates to requirements moving in the direction where metal seals may be the only viable option. Requirements may vary in the form of a combination of higher and lower pressures, higher temperatures, better leakage performance and wider range of use with one single sealing solution. Saint-Gobain HTMS sees trends in standardization and robustness where application parameters become more challenging, temperatures increase, new materials are utilized (ceramics as flange material at very high temperatures), and need for double sealing barriers in vacuum, nuclear and fusion applications.
With the world coping with a pandemic, some barriers may challenge the global metal seals market such as global political evolutions and embargos. For Saint-Gobain HTMS to remain competitive and provide the high level of quality for customers for the next two decades and beyond, they are focusing on quick turnaround service to customers’ questions and requests for support; correct and precise technical advice; and promise to deliver high-performance seals that do their job - “offering the best solution for the application.”
With HTMS joining Omniseal Solutions™, the best sealing solution can now be metal or polymer. If you feel that metal seals or polymer seals may prove valuable in your application, please contact our sealing experts!