Sealing Hydrogen: Why It Is Hard and Which Materials Are Used

Hydro is a clean energy carrier being heavily invested in, but sealing hydrogen is one of the most difficult technical challenges for compressors and pipelines.

The main challenges

• The molecules are very small and light, so they easily penetrate many types of polymers and metals, causing leaks.
• Hydrogen can cause metal embrittlement (hydrogen embrittlement).
• Harsh operating conditions: according to Freudenberg Sealing Technologies, pressures can exceed 700 bar, temperatures range from cryo to over 150 degrees C.
• Hydrogen is highly flammable, so leaks are both dangerous and costly.

Solutions mentioned in the industry

Manufacturers develop hydrogen-resistant elastomer families that maintain durability in extreme temperatures. For centrifugal compressors, API 617 standards limit materials in hydrogen environments to a yield strength below 120 ksi or a hardness below 34 HRC to avoid hydrogen embrittlement. Dry gas seals and compatible static gaskets are used in hydrogen-rich compressors, and dry gas seals also help eliminate the common problem of oil contamination in piston compressors.

Implications for users

• Choose materials based on test data with hydrogen at actual pressures and temperatures.
• Check for static and dynamic leaks under operating conditions.
• Work with suppliers experienced in hydrogen.

References

Gasworld (Freudenberg Sealing Technologies), Greene Tweed, Turbomachinery Magazine. The article was compiled and reinterpreted by SNS-VN; brand names belong to their owners.