Joint industry project

Verification of the effect of hydrogen on the integrity of pipeline repairs

Challenge

There is a lot of work being undertaken to develop design codes for new build hydrogen pipelines as well as developing guidelines for repurposing existing pipelines to hydrogen.

More recently, there has been limited research to understand the effect of hydrogen on pipeline damage.

To date, industry has not considered the suitability of existing repair methods for hydrogen pipelines, or the need for new. Neither has consideration been given to the effect of hydrogen on existing pipeline repairs, which will be essential when repurposing an existing pipeline.

This JIP will investigate the effect of hydrogen on commonly used repair systems.

Solution

DNV proposes to carry out full-scale pressure cycle fatigue testing of the following, commonly used pipeline repair systems:

  1. Type B (snug fitting) welded shell
  2. Stand-off welded shell
  3. Composite wrap
  4. Epoxy shell
  5. Temporary repair system
  6. Welded split tee
  7. Grouted tee.

Although not repairs, the latter two are an integral part of the pipeline intervention process.

To quantify the effect of hydrogen, two identical 24” dia test vessels will be constructed. The repair systems will be installed onto each vessel considering worst case situations; repairs (1), (2) and (5) will installed over a hole in the test vessel (to equalise the pressure within the pipeline and annular gap), and (3) and (4) will be installed over a deep patch defect (leaving minimal thickness for hydrogen to permeate through). One vessel will be cycled with water to obtain baseline performance data, the second will be cycled with hydrogen. Failure for a repair will be defined as a leak. The effect of hydrogen will be quantified by comparing the results from the two tests.

Laboratory testing will also be carried out to quantify the effect of hydrogen on the composite system and its bond to the pipeline, and the characteristic behaviour of the epoxy system.

Benefits

The work proposed is designed to inform which system(s) will be affected by hydrogen and the corresponding limitation of that repair system.

This will provide essential knowledge for repurposing a pipeline, confirming whether a particular repair has the potential to limit the intended service life of the pipeline.

This project will also demonstrate the suitability of these standard repair systems for remediation of damage that may be incurred on a hydrogen pipeline.

Project details

Start date: July 2026
Duration: Up to 36 months

Project partners

Scope developed in partnership with National Gas, Cadent, and SGN.

The project is open to additional partners.