Understanding Hydrogen Permeation Testing on Non-Metallic Materials

As more countries join together and commit to decarbonization following a declaration of a climate emergency, the demand for clean energy has never been greater. The need to realize the potential of cleaner, smarter energy sources like hydrogen is now more urgent than ever. If countries are going to meet their net zero emissions targets, it is widely acknowledged that hydrogen is going to be required to play an essential role.

According to the Hydrogen Council, there are currently over 30 countries with hydrogen roadmaps, and 228 large-scale hydrogen projects announced across the value chain, with 85% located in Europe, Asia, and Australia. If all projects come to fruition, total investments will reach more than $300 billion in spending through 2030. 

The successful deployment of hydrogen, however, will be critically dependent on the appropriate infrastructure and materials (including elastomers, thermoplastics, and composites), and the assurance and testing required to ensure their safety and longevity. 

Why is hydrogen permeation testing the solution?

Due to hydrogen’s small molecular size, it can permeate through polymeric, or non-metallic, materials much faster than methane or other gases traditionally associated with fossil fuels. This includes composites comprising a high proportion of glass or carbon fibers such as those used in pipelines. This means it is vital to identify which materials behave best, how well they resist hydrogen, and how long they can be expected to remain serviceable. 

Hydrogen permeation testing can provide manufacturers with important knowledge such as how much hydrogen is going to pass through the material if decompression cycles are going to compromise structural integrity, and if the material will be able to stay in service for an agreed period of time.

The testing has long been a critical part of the oil and gas industry’s safety processes, measuring permeability characteristics of deep well components such as seals, pressure barriers and liners. As the hydrogen economy expands, more and more industries beyond oil and gas, and hydrogen generation and transmission, are also looking to hydrogen, making the testing more commonplace in other industries such as aerospace, transportation, and heavy industry for items such as fuel system components, hydrogen storage tanks, and chemical processing infrastructures.

What is hydrogen permeation testing?

Hydrogen permeation testing involves analyzing three key aspects of a material’s performance. Firstly, a high-pressure gas permeation test can measure how quickly hydrogen passes through materials in comparison, for example, to methane, and at pressures up to 150 bar and temperatures from sub-zero to 200C. Element, for example, currently conducts tests with hydrogen on elastomers and thermoplastics at pressures of 150 bar with plans to increase this capability to 600 bar and has been able to compare permeation rates to previously tested gases.

The diagram below shows hydrogen versus methane permeation through a thermoplastic at 40C and 40 bar, with hydrogen permeating approximately 40 times faster than methane.

Secondly, as part of the permeation process, gas becomes dissolved in the material. When the applied pressure is removed, this gas tries to escape from the material and can cause damage in the process, referred to as rapid gas decompression (RGD) damage. Some gases cause significant problems to non-metallic materials including composites. The potential for hydrogen to cause damage needs to be investigated due to the risk of it affecting component integrity, as shown in the GRE pipe wall below. This testing can be undertaken at pressures up to 150 bar and 150C.

The third aspect focuses on aging, examining how non-metallic materials behave long-term when exposed to hydrogen. This is addressed by measuring changes in mechanical performance over time when the material is saturated with hydrogen. In composites, it is the interface between the fibers and the resin matrix where degradation mechanisms might become evident. This testing can be undertaken at 150 bar and 150C for many months to replicate or accelerate in-service conditions.

A long-term aging test can also be combined with a decompression test to see if aging degradation results in a reduction in decompression resistance.

To which standards do Element test for non-metallic materials?

Element commonly tests to a variety of industry-recognized standards, including: 

• Permeation ASTM D1434, ISO 2782-1
• RGD ISO 23936
• Ageing ISO 23936
• NORSOK M-710
• Plus, many NACE and API-relevant standards

In addition, Element can work with you to design and implement customized permeation test programs, which we frequently provide to clients for components such as O-rings and sealing elements. If required, we can also integrate several polymer testing methods into a single test program.

Key considerations when preparing to undertake hydrogen permeation testing?

When preparing to test, it is important that the manufacturer is clear about what they would like to achieve from the process, whether this is identifying the permeation rate or understanding and modifying the material or component to reduce permeation. The sample also needs due consideration to ensure the success of the program.

Questions that might need to be given advance consideration include the length of term the component or material will be in use, if decompression is likely to be an issue during operation,
if the component will be in an enclosed environment where accumulation of permeated H2 could potentially become hazardous, and if a long pipeline permeating m3 of H2 will be economically viable. Our hydrogen experts work closely with the manufacturer in preparing to test, helping to ensure the right questions have been asked to ensure a smooth test process.

Element has 30 years experience of in testing materials in high-pressure gas environments and is now sharing its expertise developed in the oil and gas industry with other industries looking towards utilizing hydrogen. A member of the Henry Royce Institute committee, the UK’s National Institute for Advanced Materials Research and Innovation, Element has also participated in the writing of the ISO 23936 series of Standards.

With very few test houses that are able to demonstrate proven expertise and capability in this sector, our experts have built up a wealth of experience in permeation and decompression damage mechanisms including visual observation of the phenomenon at high pressure for a variety of materials and components. 
   
For more information about hydrogen permeation testing, contact us today.