Industry News: Energy

Tested gaskets enhance the safety in hydrogen applications

Hydrogen system operators increasingly demand reliable tightness of gaskets. KLINGER Dichtungstechnik can provide customers with exact characteristics data based on detailed test procedures.

To make flange connections “calculable”, test standards have been devised that specify the ways in which specific tightness characteristics should be determined. Key among these standards is EN 13555, which describes leak-tightness tests including one that uses helium as test gas at an internal pressure of 40 bars (580 psi). KLINGER Dichtungstechnik has already published many data sheets for its products, with characteristic values that can be used to calculate flange connections.

Contacts mentioned in the article:

Benjamin Floegel, Head of the materials testing laboratory at KLINGER Dichtungstechnik

Sealing for hydrogen applications: comprehensive testing

Naturally, users and customers benefit greatly from information that gives them an additional assurance of safety in joining their flange connections for hydrogen applications. This includes, for example, the availability of reliable sealing characteristics to calculate the specifications for safe hydrogen applications. To this end, KLINGER Dichtungstechnik has carried out a large number of EN 13555 tests at the mandatory minimum gasket compression values with helium in-house as well as commissioning tests with hydrogen at an external partner.

The following materials were extensively tested:

  • KLINGER top-chem 2000
  • KLINGER top-chem 2000soft
  • KLINGER top-chem 2003
  • KLINGER CompenSil

On the KLINGER hardness test bench, seals are performance tested under high material pressures and gasket compression.

“As we don’t have the necessary equipment for testing with hydrogen and cannot carry out measurements with this gas on site for reasons of safety, we have outsourced the hydrogen tests to an accredited lab,” says Benjamin Floegel, Head of the materials testing laboratory at KLINGER Dichtungstechnik. For each gasket material, four DN40/PN40 test specimens were taken directly next to each other from a sheet of sealing material. One gasket each was tested in the KLINGER test lab with helium at 10 and at 40 bars (145 to 580 psi). The other two gaskets were tested in the accredited test labs of amtec Messtechnischer Service, also at 10 and 40 bars (145 to 580 psi), with hydrogen as the medium.

A KLINGERSIL gasket on the test bench before a test.

Helium-based test data

The color- and odorless inert gas helium has a similar atomic radius to the hydrogen (H2) molecule, which consists of two hydrogen atoms. Although, like the highly flammable H2, helium can pass through tiny openings and channels, it is harmless. That is why Benjamin and his team can handle it in their own laboratory and carry out precision gasket testing. “To determine how KLINGER’s high-quality gasket materials behave with hydrogen under the same conditions, we commissioned comparative tests on various KLINGER sealing materials,” says Benjamin.

“When the results came back, we were pleasantly surprised, as they were almost identical to those for helium.”

Benjamin Floegel heads the materials testing lab at KLINGER Dichtungstechnik.

PTFE gaskets exceed expectations

“For users and our customers, this means that flange connections for hydrogen applications can be designed using the existing tightness parameters for helium – that’s a big advantage,” says Benjamin.

The graphs below shows the similarity in readings for helium and hydrogen – more information available on request:

The tests highlighted another advantage: all of the KLINGER PTFE materials tested delivered much better results at 10 and 40 bars (145 to 580 psi) hydrogen than in the equivalent tests with helium.

This can be clearly seen in the graph for KLINGER top-chem 2003:

With hydrogen applications becoming ever more widespread, KLINGER Dichtungstechnik can now skillfully leverage its experience margin. Reliable gaskets are a vital component in all industry sectors – from the chemical industry to power generation to mobility.

“Nothing is one hundred percent leak-proof. But based on our results, we can now clearly demonstrate the tightness classes that can be achieved at different compression values with our products for hydrogen.”

Benjamin Floegel is delighted with the positive results of the leak tests.

Frequently asked questions (FAQ)

How are gaskets tested at KLINGER Dichtungstechnik?

At KLINGER Dichtungstechnik, we subject all batches produced to a wide range of tests, including chemical resistance to various media, leakage measurements, and thermal and mechanical tests. In addition to the quality assurance tests that accompany production, we carry out many other standard and special tests, for example to obtain characteristic values.

How is leakage measured in the gasket test procedures?

This depends on the underlying test standard. For leakage testing in accordance with EN 13555, we use both the differential pressure method and helium mass spectrometry; for tests based on DIN 28090-2 or DIN 3535-6, we use gas burettes or thermal mass flow meters, among others. All tests at KLINGER Dichtungstechnik are carried out with helium or nitrogen. But we can also perform leakage measurements with various liquids, for example in accordance with ASTM F 37.

Fact box

Did you know ...

  • … that all of the gasket specimen tested here with helium and hydrogen had a geometry of DN40/PN40, an outer diameter of 92 millimeters and an inner diameter of 49 millimeters?
  • … that the EN 13555 standard explicitly specifies leak testing with helium? The reason for using this inert gas is also to do with safety, as it is harmless, unlike the highly flammable, reactive hydrogen.
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