KLINGER Innovation

Gaskets for High-Pressure Hydrogen Applications

KLINGER Kempchen’s product range includes the perfect gaskets for high-pressure and hydrogen applications. The leakage losses of its metal gaskets are so small as to be undetectable.

Given the media attention hydrogen has been receiving lately as an energy source for mobility and steel production, one would think that this is a brand-new medium. In truth, refineries have been working with this molecular gas, which goes by the chemical formula H2, for over 100 years. The benefits and drawbacks of hydrogen have been explored and known for a long time, so it’s not surprising that it is used in industry. KLINGER Kempchen, too, has delved into the topic, especially with regard to developing the right gaskets for high-pressure hydrogen applications.

Contacts mentioned in the article:

Torsten Bial, Head of Engineering at KLINGER Kempchen

Adapting gasket material to operating pressure

“The higher the pressure in a system, the greater the demands on the gaskets,” says Torsten Bial, Technical Manager of the Engineering department at KLINGER Kempchen. At elevated hydrogen pressure levels above 40 bars, he says, there are a few gasket types that can reliably limit leakage losses to an acceptable level. “In the low-pressure range, below 25 bars, by contrast, there are almost no limits to what can be used, with a large number of available gasket types that provide a reliable seal,” says Torsten. Simple flat gaskets can also be used here, with the caveat that the connection’s design must provide a sufficient contact pressure to ensure the static friction force required. This prevents gasket failure even under unfavorable operating conditions or in the event of poor installation.

Minimize losses with metal gaskets

Regardless of the pressure range, a leak-prone design is a no-go in hydrogen applications – and not, as one might expect, due to the gas’s high flammability. After all, the minimum tightness required by VDI 2290 (tightness class L=0.01) prevents an explosive atmosphere forming in most environments. A bigger issue, says Torsten, are the economic losses that result from leaky hydrogen systems:

“Hydrogen is the energy source of the future and, as such, a precious commodity. The greater the leakage rates, the faster hydrogen is lost through sealed joints. This can quickly add up to a few kilos, and in larger installations with many pipe connections, as much as several tons over the gaskets’ expected service life.”

Torsten Bial is Head of Technology (Engineering, Laboratories, Development departments) at KLINGER Kempchen.

These losses can only be reduced with high-quality gaskets and sealing connections that have been professionally designed and assembled. To minimize losses to below the measurable range, the only viable option is to use all-metal gaskets.

Precision gasket testing under hydrogen conditions

When leak testing gaskets, KLINGER Kempchen leaves nothing to chance. “We test gasket materials 24/7. Whether simple, flat graphite gaskets, fiber and PFTE gaskets, semi-metallic types or all-metal beveled gaskets, we carry out leakage measurements with hydrogen from ten to 200 bars,” says Torsten.

The resulting data provides the foundation for numerical models with which the total hydrogen losses in complete systems with flange connections can be calculated for various pressure levels. These models also take into account installation conditions such as tightening forces, gasket compression and operating pressure.

They provide valuable information regarding a system’s cost-effectiveness, especially for plants with a large number of flange connections. These calculation models are currently being refined and should be available to customers in 2024.

Frequently asked questions (FAQ)

What are the selection criteria for gaskets in hydrogen applications?

The main factor when selecting gaskets for hydrogen applications is the system’s operating temperature. This is because hydrogen can cause corrosion and becomes even more corrosive at higher temperatures. The operating pressure is a further consideration: The higher it is, the higher the required tightening torque of the flange bolts to achieve a sufficient form-fit and contact pressure. Also important is the gasket material’s resistance, always bearing in mind the medium and the system’s operating temperature and pressure. Finally, the tightness requirements must be considered, i.e. how much hydrogen loss is acceptable. After all, the leakage behavior of a connection also depends on the type of gasket used.

Which gasket types are not resistant to hydrogen?

Essentially, with a few exceptions, all gaskets are resistant to hydrogen. In the case of metal gaskets, certain non-ferrous metals as well as titanium and nickel are unsuitable for high-temperature hydrogen applications.

What do the terms permeation and diffusion mean in the context of hydrogen?

Permeation is the extent to which a gas penetrates into a solid.  Hydrogen molecules decompose on the surface of metals to form hydrogen atoms, which can penetrate through the gaps in the metal lattice due to their small size. This process is referred to as diffusion. When the hydrogen atoms recombine to form molecules after leaving the metal, this is known as desorption.

Visit KLINGER at the ACHEMA 2024 from June 10 to 14 in Frankfurt am Main, Germany and learn all about the KLINGER Group’s gasket materials for hydrogen applications. You will find us in Hall 8.0, Stall B4.

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