Evaluate and Assess the Development of Pipeline System Repair and Maintenance Technologies in Hydrogen (H2), H2-Natural Gas Blends, and Natural Gas Pipelines

Overview

Main Objective

The proposal will address concerns associated with repair of steel and plastic pipelines that will transport H2 or H2-NG blends. Addressing these concerns will increase the industry's confidence in using conventional pipeline repair methods to ensure the integrity of the H2 or H2-NG blended pipeline systems.

Public Abstract

Project Description: Blending hydrogen into natural gas pipeline networks or converting existing natural gas pipeline networks to hydrogen pipeline service will require Pipeline networks undergo proper inspections and maintenance to ensure the integrity of the pipeline is maintained. Pipeline repairs are often performed while an operating natural gas pipeline is in service, using established methods proven for natural gas pipeline service, and have a long successful history for maintaining the pipelines integrity. While some aspects of pipeline repairs have independently been evaluated for hydrogen (H2) or H2-natural gas (NG) blended service, there are still many areas with significant concerns.

The most common repair methods used to reinforce steel pipelines consist of applying a full-encirclement repair sleeve over the damaged portion of the pipeline. The repair sleeves come in many different forms that include welded steel sleeves, bolt-on steel sleeves with elastomer seals, and composite sleeves. Each of these repair sleeves have risks associated with them when it comes to the materials being exposed to H2. Under certain conditions, H2 exposure can result in hydrogen embrittlement (HE) of the steel, reducing the fracture toughness and fatigue properties, and is the primary pipeline integrity concern. Hydrogen may also reduce the mechanical properties of elastomers and composite sleeves. When it comes to plastic pipe repairs for H2 or H2 – NG blends, the two most common repair methods are to squeeze the pipe closed to facilitate a pipeline replacement or to install a repair sleeve over the damaged portion of the plastic pipeline by electrofusion.

Anticipated Results: The project will produce a report that incorporates:

1. the current state of the art for pipeline repairs for H2 or H2 – NG blended natural gas pipelines and
2. the results of testing to address known gaps in the pipeline repair methods described to quantify the integrity of the pipeline repairs in H2 or H2 – NG blends environments.

Potential Impact on Safety: The results from this project are anticipated to guide future industry research, testing, and industry document development to ensure the integrity of future pipeline repairs or pipeline repairs to existing pipeline systems that may be converted to transport H2 or H2 – NG blends. Specifically, it is expected that the results from this work will be referenced as justification for future revisions to ASME B31.8, Gas Transmission and Distribution Piping Systems, that pertain to the incorporation of H2 or H2 – NG blend requirements into the Code.

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