Session: MF-05-02 Fitness-For-Service and Failure Assessment-2

Paper Number: 154573

154573 - Fracture Mechanics at the Core of Hydrogen Pipelines Design: A Fracture Mechanics Approach in Design Life Prediction Based on Material Performance Measured in H2 Environment 

Abstract: 

Energy transition from the current fossil fuel-based economy to the renewable and sustainable technology era is one of the most important challenges of the future. Different promising options are being investigated, with particular attention to carbon capture & storage and hydrogen-based energy systems. Onshore and offshore pipelines have been identified as the primary mean for H₂ transport and are now on stage for pipeline contractors.

In the transportation of gaseous hydrogen one of the main issues is associated to hydrogen embrittlement (HE), in particular, gaseous hydrogen can dissociate into atomic hydrogen and permeate the metal matrix causing embrittlement of the steel, especially for high steel grades, manifested by a reduction in the material toughness and tensile ductility of the steel and an increased fatigue damage behavior.

Hydrogen embrittlement reduces the steel’s tolerance to defects, making the pipeline more vulnerable to failure and potentially susceptible to worsen relevant failure modes. Therefore, for evaluating the effect of HE on metals, an Engineering Critical Assessment (ECA) using fracture mechanics principles can be used, to assess the consequences on fatigue resistance and fracture toughness properties for carbon steel pipelines in hydrogen service. The fracture mechanics assessment will also concur to the definition of the wall thickness, the fracture toughness and the fatigue testing requirements.

The design by fracture and fatigue for hydrogen offshore pipelines is described in the paper along with a review of applicable standards and the ongoing research to fill the area of lack of evidence with respect to assumptions and material behavior, considering that for offshore pipeline no standard exists regulating hydrogen gas transport. Now, only a JIP from DNV (H2Pipe) is targeting the development of a DNV Recommended Practice within 2024.

The paper addresses also the effect of transporting hydrogen not only on the parent pipe material but also on seam weld material as well as on girth weld material considering that the latter may experience applied loads (peak and fatigue) more demanding than the rest of the pipeline. Some input data for the design as fracture toughness and fatigue properties are taken from results of SAIPEM testing campaign at 200bar in pure H2 environment.

The paper provides the results in terms of fatigue and fracture resistance by design approach for new pipelines and by recommending interventions and remedial actions for existing lines to be retrofitted in hydrogen service. The work is part of the new qualification process required by an EPCI and T&I contractor to guarantee the integrity of the new or the repurposed pipelines for Hydrogen transport.

Presenting Author: Daniele Scarsciafratte Saipem SpA

Presenting Author Biography: Daniele has a M.Sc. in Mechanical Engineering (Sapienza University of Rome). He has more than ten years’ experience with Saipem in the Oil & Gas sector. Worked in Welding Integrity department for Saipem Offshore division reaching the role of Senior Welding Integrity Engineer. Since 2020 he is Subject Matter Expert for Saipem innovation projects on Hydrogen and CO2 Offshore pipeline including the partecipation to the DNV JIP H2Pipe. He is currently member of Hydrogen topic group of EPRG (European Pipeline Research Group) and of ASME B31.12 EU IWG.

Authors:

Daniele Scarsciafratte Saipem SpA
Enrico Torselletti Saipem SpA
Elvira Aloigi Saipem SpA
Angelo Santicchia Saipem SpA
Giorgio Arcangeletti Saipem SpA