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Executive Summary

Transporting hydrogen by pipeline may be considered an efficient, economical and safe method to support Canada’s goal of net-zero greenhouse gas (GHG) emissions by 2050.

Canada possesses an extensive pipeline network that can be considered for potential repurpose for hydrogen service, in conjunction with blending hydrogen into the natural gas grid. Coatings and liners used in pipeline infrastructure are essential for preserving asset integrity and ensuring the protection of personals, assets, local communities and the environment. It is important to align regulations, codes and standards (RCS) with new coating and liner technologies to support the safe, efficient and effective operation of hydrogen pipelines.

The purpose of this report is to review potential coating and liner technologies, and identify the need for standards based solutions to support their use on hydrogen and hydrogen/natural gas pipeline systems. This report provides a comprehensive review of potential coating and liner technologies for hydrogen pipeline and equipment, as well as the relevant standards, codes, best practices and regulations.

In addition to protecting pipeline infrastructure from corrosion and mechanical damage, coatings and liners could potentially help mitigate the technical challenges posed by gaseous hydrogen and new technologies used in hydrogen service pipelines. These challenges include gaseous hydrogen embrittlement (HE), low energy transportation efficiency, repurposing existing natural gas pipelines for hydrogen service, blending hydrogen into natural gas pipelines, and the side effects of HE inhibitors.

Some existing and emerging technologies for hydrogen pipeline coatings and liners include polymer, metal, ceramic and composite systems, which may be able to address the challenges mentioned above.

• Polymer: Polyethylene (PE) and epoxy resin are the most widely used coating and liner systems in natural gas pipelines, and can withstand typical operating conditions of a hydrogen pipeline. Commercial flow efficiency epoxy coatings are most likely applicable to hydrogen pipelines. Polyvinyl alcohol (PVA) and polyvinylidene chloride (PVDC) show good hydrogen barrier performance, but ease of application and chemical resistance need to be improved.
• Metal: Nickel, zinc, copper, aluminum and stainless steel may be expected to perform effectively as a hydrogen barrier coating due to low permeability and maturity of application methods.
• Ceramic: Oxides and nitrides may show efficient hydrogen barrier performance, but their use in hydrogen pipelines is restricted by their brittle nature and challenges in scaling-up. Black oxide and vitreous coatings can be applied to large pipeline structures.
• Composite: Fiber reinforced polymers (FRP) and spiral interlocking pipes have been used for hydrogen service pipelines. Their performance attributes for hydrogen permeation, mechanical strength, flow efficiency and corrosion resistance depend on the material selected for individual layers and their fabrication methods.

For external coatings on hydrogen pipelines, their function is similar to those applied on natural gas pipelines. Existing technologies, best practices, standards and regulations for external coatings can be applied to hydrogen pipelines with revision, in order to comply with more stringent safety requirements expected to emerge in the coming years, as outlined in the international hydrogen pipeline standards.

Internal coatings or liners used in hydrogen pipelines must maintain their material properties and structural integrity – either completely unchanged or within permissible limits. A product qualification protocol can reference existing standards for internal coatings and liners in natural gas pipelines, with modifications to test conditions and acceptance criteria to align with hydrogen pipeline requirements.

Commercially available internal coatings and liners made of epoxy, PE, and FRP are expected to meet the minimum requirements for hydrogen service. The best practices for these coatings and liners as per natural gas pipelines may also be applicable to hydrogen pipelines, as long as they continue to fulfill their intended purposes, such as friction reduction, corrosion protection and erosion resistance.

While the effectiveness of coatings and liners in addressing the challenges of hydrogen pipelines has not been experimentally proven, their potential to mitigate HE and improve flow efficiency is considered. To promote the advancement of hydrogen service pipelines and coating and liner technologies, there are opportunities to streamline the process through standardization. The following recommendations are prioritized to facilitate safety, quality, economy, innovation and sustainability.

• Establish stand-alone standards for pipeline internal coatings, following the style of external coating standards like CSA Z245.20 series and CSA Z245.30.
• Standardize material qualification protocols for hydrogen service pipelines as a precondition of standardizing hydrogen infrastructure components, such as coatings and liners.
• Standardize qualification protocols for internal coatings and liners as HE mitigation measures when the best practice of testing hydrogen barrier performance is established by industry or academia.
• Standardize the best practice of adopting internal coatings and liners in pipeline rehabilitation derived from technical specifications provided by various manufacturers and contractors.Standardize the best practice and qualification protocols of emerging coatings and liners for hydrogen pipeline service.