Permeation and embrittlement are issues that stand in the way of realizing a viable and mature hydrogen infrastructure. For pressure and temperature sensors, using materials that protect against these conditions is key to safety and profitability in the chemical industry.
As mentioned in part 1 of this series
, hydrogen permeation and embrittlement are major issues that must be overcome to realize a mature hydrogen infrastructure. Molecular hydrogen (H2) can go through most non-metallic materials. And when dihydrogen comes into contact with metal surfaces, it takes relatively little energy – even in ambient conditions – to dissociate the gas into its atomic form, then into the ions that can so easily penetrate most metals’ lattice structure. The greater the energy in the environment, such as extreme process temperatures and pressures, the faster the permeation and embrittlement will occur in storage tanks and pipelines.
Measuring instruments also face the same issues, leading to signal drift and mechanical failure. Fortunately, there are ways to overcome these and other challenges.
Materials That Resist Permeation and Embrittlement
Measuring instruments used in a hydrogen environment should be made with metals that have a closely packed cell arrangement. They include 316L (316 stainless steel with a low carbon content), 316Ti (titanium-stabilized version of 316), and other austenitic steels, which are ideal for highly corrosive and high-temperature environments. Special alloys such as Hastelloy C276, Inconel 718, or 2.4711 (Elgiloy®) are also well suited for hydrogen applications.
Coatings That Resist Hydrogen Permeation
For extra resistance to hydrogen permeation, the austenitic steel or special alloy can be coated with a metallic barrier. Nickel, aluminum, and copper exhibit low hydrogen permeability, but gold is by far the metal that best resists permeability, even at high temperatures.
Instruments That Minimize H2 Leakage
Seals in pressure gauges are common places for hydrogen to escape. For this reason, the gauges used in hydrogen applications should have a metallic seal rather than one made of an ordinary polymer. A fully welded design also prevents leaks. In addition, choose pressure instruments that have undergone a helium leak test as part of their quality assurance process.
Instruments That Withstand Extreme Process Conditions
In hydrogen fueling stations, the gas is stored in pressures as high as 15,230 psi (1,050 bar). And for liquid hydrogen, temperature measurement solutions need to maintain their accuracy at or below −423°F (−253°C).
WIKA, Smart in Sensing for the Chemical Industry
For safety and performance, hydrogen applications require measuring instruments designed to meet extreme conditions, and specialists with years of chemical expertise and industrial experience.
A global leader in the field of high-performance measurement solutions, WIKA is a proven partner for companies that produce, transport, and use hydrogen. From hydrogen compression and filling stations to mobile and stationary fuel cells, WIKA USA offers quality instruments for the industry’s entire value chain, whether the H2 is produced conventionally or with renewable resources.
This article follows Energy Expenditure as a Factor in Hydrogen Transport and Storage
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