Five challenges of hydrogen high pressure testing

Five challenges of hydrogen high pressure testing

Over the past few years, the concept of an economy in which hydrogen plays an important role gained significant traction, especially with organizations aiming to reduce their carbon emissions while envisioning a carbon-free energy grid. The advances made in storing electricity in the form of hydrogen can have a major impact on ensuring grid stability and connecting the energy network.

Developing this hydrogen industry does of come with its own challenges. The special properties of the hydrogen molecule can make it hard to handle. Practical applications such as storage tanks, cylinders, pipes, valves and other components used by the energy, automotive and oil & gas industries must always be tested and certified. These test procedures may vary from basic burst tests to complex cycle testing procedures in both low and high temperature ranges. If you are involved in performing high pressure tests with hydrogen in any way, being aware of the following five hydrogen challenges will surely assist you:


1. Hydrogen embrittlement increases risk of failure

According to NACE International, hydrogen embrittlement can be a cause of corrosion which “can seriously reduce the ductility and load-bearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress”. As this phenomenon does not affect all metals similarly, it is important to carefully select the right materials.

2. Hydrogen heats up during the expansion process

Hydrogen, together with helium, is a gas that behaves different from nitrogen, air and other gases during a pressure drop (the so called isenthalpic process). Contrary to many other molecules, hydrogen actually becomes warmer when it expands. This effect is also referred to as a reversed Joule-Thomson effect. When working with hydrogen under high pressures of up to 700 bar, the Health and Safety Executive points out that it is critical to understand the implications of this behavior in order to develop safe solutions.

3. Hydrogen systems require accumulators to provide a reasonable amount of energy

Although the energy per mass of hydrogen is the highest of any fuel, its low ambient density results in a low energy per unit volume. To increase the energy density of this energy, hydrogen gas is typically stored in tanks at pressures between 350 and 700 bar or even higher.

4. Hydrogen is highly explosive

Many international organizations recognize the broad flammability of hydrogen. According to a NASA project, “a 4 percent to 74 percent concentration in air and 4 percent to 94 percent in oxygen” is sufficient to create a flammable mixture. Preventing hydrogen from mixing with air and oxygen in confined spaces is therefore an advice that must not be taken lightly.

5. Hydrogen diffuses easily through materials due to its light weight

Due to its chemical structure and its light atomic weight, hydrogen easily diffuses through materials and is extremely difficult to contain in confined areas as a result. The right sealing technology and materials are critical for developing safe hydrogen testing equipment that minimizes hydrogen leakages and counter-act hydrogen embrittlement.





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