Hydrogen is being explored globally as the energy source of the future. It is on track to be utilized across increasing fields of application as part of the transition to low-carbon energy sources and net-zero emissions.
For all of its considerable benefits, hydrogen does present significant hazards and challenges in use. Colorless and odorless, hydrogen does not readily make its presence known. It also evaporates easily and is extremely flammable. These qualities together amplify the need for mechanical seals that are properly engineered to effectively contain hydrogen within a system, and for rigorous testing and verification of all seal components.
Challenges to Hydrogen Seals
In operation, hydrogen seals must be designed for the challenges presented in context. These can be grouped into three categories:
- Extreme temperature variations in generating, processing, and transport.
- Physical interaction with other materials and elements present.
- Chemical reaction with other materials present.
All system components in direct contact with hydrogen must be suitable and tested in order to guarantee safety in use, storage, and transport. Hydrogen-induced stress corrosion (hydrogen embrittlement) presents a risk for highly stressed pressurized components. Leaks must be detected and repaired promptly to maintain the integrity of the seal and system.
Stein Puts Hydrogen Seals to the Test
Stein Seal Industrial, a leading expert in the design and manufacture of hydrogen seals, is also an industry leader in seal testing and verification. There are many ways to test and verify a hydrogen seal:
The testing/verification process generally starts with a visual inspection. Qualified professionals check each component for visible signs of damage, wear and tear, fatigue, or other indications that performance might be degraded or the seal might be compromised.
With pressure testing, the seal is placed under pressure with an inert gas. The system pressure is then monitored over a specific timeframe, during which a drop would be considered an indication of a potential leak.
HELIUM LEAK DETECTION
In order to assess the ability of the seal to safely contain hydrogen, the system is tested using helium, a gas that resembles hydrogen in weight and size, but not in volatility. With helium in place as a tracer gas, even the smallest leaks can be detected using a mass spectrometer.
This simple testing method involves putting the seal under pressure and submerging it in water. Any leaks in the seal will cause the formation of air bubbles.
In ultrasonic testing, high-frequency sound waves are used to detect internal cracks and leaks. This highly sensitive technique can find flaws that visual inspection can miss, such as on the interior surfaces of the system components.
ACOUSTIC EMISSION TESTING
In acoustic emission testing, the seal is pressurized and subjected to intense sonic scrutiny with highly sensitive sound-detection equipment. Engineers can analyze the sound recording, listening for telltale sounds that are created by gas leaving the system through a leak.
When hydrogen escapes, it rapidly expands and cools, affecting the temperature of the system itself at the point of the breach. This kind of thermal anomaly is discernible through infrared, or thermal, imaging.
DYE PENETRANT INSPECTION
In dye penetrant inspection, a colored dye is applied to the seal and then simply wiped away. Cracks and other surface flaws will capture trace amounts of the dye, revealing themselves under black light.
HYDROGEN LEAK DETECTION SPRAY
In a process similar to dye penetrant inspection, a leak detection spray is applied to the entire mechanism. This spray reacts chemically to the presence of hydrogen, turning a vibrant color at the point of contact with any escaping hydrogen gas.
Stein Seal Industrial is working on innovative sealing solutions for the Hydrogen focused markets. Building on our patented Hydroload and Hydravent sealing elements.
We take these design and material requirements to our R&D testing facility. There we develop testing protocols that mimic the critical environment and operational confines of demanding Hydrogen seals.
Whichever method is used, Stein Seal Industrial performs all of its hydrogen seal testing to industry-established standards and best practices. Every Stein-built hydrogen seal can be relied upon to provide safe and effective performance over a long service life.