Valve Testing for Hydrogen and Carbon Capture (CCUS) Applications

The expansion of the ‘New Energy’ or low-carbon economy means the infrastructure supporting it must evolve as well. This ensures that they can handle the two most challenging chemical engineering fluids – Hydrogen (H2) and Carbon Dioxide (CO2). 

With this, plant managers and manufacturers must consider hydrogen valves as the primary defense against environmental hazards and significant financial losses. Verifying that such components withstand the rigors of high-pressure service requires a crucial shift in material selection and traditional valve testing. 

Preparing Valves for Hydrogen and CCUS

The technical aspects of hydrogen valves and Carbon Capture, Utilization, and Storage (CCUS) require those involved to manage extreme pressure fluctuations and aggressive chemical interactions. The concept of ‘zero leakage’ in New Energy applications must be observed. Even a tiny seal failure may lead to explosions. 

CCUS system leakage may also result in a swift localized freezing. With this, valve preparation must be about a thicker casting, meticulous fugitive emissions testing, and metallurgical validation. These processes ensure that the valves maintain a secure pressure throughout their service lifespans. 

The Hydrogen Challenge

Chemists and engineers consider hydrogen the molecular world’s ultimate ‘escape artist.’ It’s the tiniest and lightest element, presenting distinct physical and chemical challenges that make standard industrial valves useless within months. 

H₂ Molecule Size and Leakage Risks

With hydrogen molecules being very small, they can migrate through microscopic pores and crystalline lattices. This leads to serious risks of invisible leaks. In a high-pressure system, the molecule spreads through the body gaskets and the valve packing. 

There is a way to counter this, though: facility managers and manufacturers must have the hydrogen valves undergo specialized Helium leak testing. This verifies that the seals are tight enough to contain the gas. 

Hydrogen Embrittlement of Metals

Hydrogen Embrittlement (HE) is the most dangerous risk. It’s when the hydrogen molecules spread through the surface of high-strength steel. They dissociate into atomic hydrogen and diffuse to the metal’s grain boundaries. As a result, the hardware becomes brittle and glass-like. 

Carbon Capture (CO2) Valve Requirements

In CCUS applications, Carbon Dioxide is known to degrade seals and mechanical integrity, especially during phase changes. 

High Pressure and Rapid Decompression

In CCUS systems, CO2 is generally transported in a highly critical state, meaning it behaves like both gas and liquid. Furthermore, this must operate in pressure usually exceeding 150 bar. The danger happens during the ‘Rapid Gas Decompression’ (RGD). Once the system is rapidly depressurized, the absorbed CO2 expands dramatically as it returns to a gas. 

Elastomer Explosive Decompression (RGD)

When a CO2 is under high pressure, gaskets and standard rubber O-rings act like sponges. Once the RGD event occurs, the gas trapped inside the elastomer will try to escape as quickly as the material can breathe. This results in an ‘explosive decompression’ where seals burst from the inside out. Experts always recommend using a specialized anti-RGD seal for any CCUS valve. 

Testing Standards for New Energy

Battery tests are conducted to assess whether the valve is ready for and can survive the New Energy market. In addition to the usual API 598 hydrostatic checks, fugitive emissions testing and high-pressure gas cycling must also be conducted. 

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High-Pressure Gas Testing

Performing liquid testing won’t be enough for hydrogen. Valve manufacturers must use High-Pressure Gas Testing (HPGT) using Helium or Nitrogen. The former is the preferred rest medium because its molecular size is closer to that of hydrogen. 

A credible hydrogen valve manufacturer must meet ISO 15848-1 standards, specifically the Class AH or BH certifications. This refers to cycling the valves thousands of times at different temperatures while checking for possible stem leakage using a mass spectrometer. 

Material Suitability

The industry consensus for hydrogen valves centers on the ASTM A182 F316/316L stainless steel with a minimum nickel content of 12%. This helps stabilize the austenite grain structure, which is more resistant to hydrogen atom migration. 

Moisture in CCUS applications can convert CO2 to carbonic acid. With this, internal trim components are generally upgraded to Inconel 625 or Hastelloy C276. This prevents crevice corrosion and localized pitting. 

Final Thoughts

With the transition to New Energy, there’s surely an increased demand for valve technology. Navigating the complexities of CCUS and hydrogen requires experts and manufacturers who understand their molecular realities. Facilities are only ready for a carbon-neutral setting when fugitive emissions testing and the selection of materials that combat embrittlement and RGD are prioritized.