MCM investigates best elastomers for hydrogen seals

BERGAMO, Italy—MCM S.p.A., part of the Angst+Pfister Group, has seen a dramatic increase in inquiries about hydrogen seals since 2020 and expects levels of interest expected to rise even more in the near future.

"Investment in hydrogen technology is massive right now," said Raffaella Villa, business development engineer at the Bergamo supplier of rubber seals for the automotive, aerospace and oil industries.

"Gas is a tricky one for elastomer seals, especially hydrogen," says Villa. "There are completely different requirements to be met than for liquids—in addition, hydrogen is the smallest molecule of all."

As the gas can slowly diffuse through the molecular structure of polymers, a particular focus is on the permeability of elastomer compounds.

While the high pressure in the pipelines makes hard elastomers the most likely choice, not all compounds behave in the same way with hydrogen.

"We are currently working on identifying the best materials but do not want to rely purely on theory and literature," says the MCM engineer.

FKM and HNBR have already been floated as potential solutions for hydrogen, but MCM also wanted to investigate precisely which elastomer is most suitable for which function.

To produce a ranking system for hydrogen applications, MCM is having its entire portfolio permeability tested by an external laboratory.

Although hydrogen itself does not damage elastomers chemically, environmental conditions can be an issue.

In general, the higher the pressure or temperature the more permeable the seals become, while chemical resistance can also be a requirement in some applications.

All these factors limit the choice of elastomer—and usually a compromise is sought. MCM aims to present its customers with reliable data on applications involving hydrogen.

The current project for Starline required exceptionally hard seals that can withstand pressure to 35 bar—but also modest temperatures from -10 to 65 degrees Celsius.

"Starline could use one of the compounds in our portfolio to develop valves for its Iberdrola project, but we are now checking what our portfolio can further deliver," said Villa.

"The portfolio is already enormous, but we would nonetheless be prepared to develop new elastomer compounds for hydrogen seals," she said. "At the end of the day, they would also be of interest to other industries such as the automotive industry."

Reliable data and choice of material are one thing—MCM is also contributing its expertise in compression and injection molding of the parts.

"The molds for such materials are not a trivial matter," said Oliviero Mismetti, project manager at MCM. "Experience is crucial for the required tolerances in manufacture (as is) knowledge for AED (anti-explosive decompression) approvals … for decompression resistant seals."

MCM's work in this field includes a collaboration with forged steel ball valves maker, Starline S.p.A. to develop valves used to produce green hydrogen, "where service in 97 percent vol hydrogen" is required.

Starline requires advanced sealing technology to support its supply of hydrogen pipeline valves to companies, according to MCM.

Clients, it said, include Spanish energy giant Iberdrola, which is "investing billions of euros in the production of green hydrogen."