Article contributed by Ian Coleman, Zachary Louden and Ernie Lackner from PLIDCO.
As hydrogen becomes an increasingly important part of global decarbonisation strategies, the infrastructure required to handle it – especially pipelines – faces new technical and material challenges. Hydrogen’s unique properties, such as its low molecular weight and potential for embrittlement, demand a shift in how the pipeline industry approaches maintenance and repair.
Why hydrogen pipelines require specialised fittings
Hydrogen behaves differently from natural gas. Its small molecular size allows it to permeate even the tiniest flaws in seals or joints, increasing the risk of leaks.
Hydrogen can also diffuse into certain metals and degrade their mechanical properties. Known as hydrogen embrittlement, this can lead to reduced ductility, increased crack initiation and a higher risk of failure under pressure.
To mitigate these risks, hydrogen service pipeline fittings must meet several key criteria:
- Material selection
The industry standard for hydrogen piping and pipelines, ASME B31.12, specifies common engineered steel materials – carbon steels, low-alloy steels, and stainless steels that are acceptable for use with pipelines containing hydrogen gas. Non-metallic components and seals must also be carefully selected and tested for hydrogen compatibility.
- Seal tightness
Because of hydrogen’s high permeability, a tight seal is essential. Designs that incorporate long sealing surfaces and high-torque installations—such as multi-bolt sleeves—help ensure leak resistance under variable conditions.
- Resistance to hydrogen embrittlement
Materials used in fittings must be resistant to the effects of hydrogen absorption over time. Proper coating selection can minimise Steel exposure to the hydrogen in the pipeline. Thorough testing and quality control are essential to verify performance under hydrogen exposure.
- Pressure and temperature ratings
Fittings must be designed and rated specifically for the intended pressure and temperature conditions of the hydrogen system, which are often higher than those for conventional gas pipelines.
Hydrogen-compatible repair options
PLIDCO® has developed a dedicated line of repair fittings specifically designed for hydrogen service pipelines.
The company’s standard Split+Sleeves and Clamp+Sleeves have been modified to meet the demands of hydrogen pipelines. They are manufactured using hydrogen-resistant materials and designed to comply with ASME B31.12.
Key attributes include:
- Manufactured with carbon steel materials in compliance with ASME B31.12 and evaluated for embrittlement and fatigue performance
- Designed with long sealing surfaces and 100 per cent pipeline contact features to maintain integrity under pressure
- Maximum allowable operating pressures (MAOPs), customised to meet the demands of high-pressure hydrogen systems, are available
- Testing at 1.5x the MAOP to ensure leak tightness and functionality
- Use of ISO 15156-compliant materials and Viton™ seals
- Clear visual identification via green markings to distinguish hydrogen-compatible fittings from standard PLIDCO® Split+Sleeve designs
- Designed for both onshore and offshore environments.
PLIDCO®’s designs support different operational strategies: fittings may be welded in place for permanent repair or, where welding is not used, removed and reconditioned for reuse in the operator’s inventory – helping reduce long-term maintenance costs.
Installation and maintenance considerations
While welded joints help to minimise the risk of leaks on hydrogen systems, in-service welding can be risky and impractical. PLIDCO’s mechanical fittings provide a safe, non-intrusive alternative when downtime or hot work is not feasible.
Each fitting is delivered with detailed installation guidance, including steps for torquing, aligning, and optional welding where appropriate. PLIDCO Engineers are on-call and available 24/7, 365 days of the year to answer any questions that may arise regarding proper fitting or seal selection and installation questions.
A proactive approach to hydrogen infrastructure
As governments and energy companies accelerate hydrogen deployment, asset integrity will be critical. Adopting hydrogen-compatible products is not just about compliance with standards like ASME B31.12 – it’s about ensuring safety, reliability, and long-term viability in a new and evolving energy environment.
PLIDCO brings 75 years of experience in high-pressure pipeline repair to this emerging space. Its hydrogen-ready fittings are a natural extension of its long-standing mission: to provide safe, efficient repair solutions that help operators maintain service continuity and minimise risk.
PLIDCO’s products are backed by the industry’s only ten-year warranty, giving asset owners peace of mind and protection for the long term.
PLIDCO’s hydrogen-compatible fittings, and other pipeline repair products, are available across Australia and the Oceania region through Tremco Pipeline Equipment, its exclusive partner in the region since 2000.
To learn more about hydrogen-specific pipeline solutions, contact sales@tremcopipeline.com.au