The Future of LTS: Evaluation of Vintage Pipeline Materials in Hydrogen Environments

Completed

Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas)
Hydrogen and Fuel Cells(Hydrogen, Hydrogen transport and distribution)

Applied Research and Development

ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Project Contact
SGN

Network Innovation Allowance

Ofgem

01 September 2020

30 September 2021

ENA months

£427,137

Energy

South East

Network Innovation Allowance

Project Contact, SGN

The following work will be carried out in 2 work packages:Work Package 1: Material testing and analysis (University of Strathclyde)The proposed test programme, using similar material to the Granton to Grangemouth pipeline, has been designed to address the gaps identified during the Phase 1 LTS study and further understand the effects of hydrogen on vintage line pipe steels. As the test specimens chosen are of the same vintage as the Granton to Grangemouth pipeline, with the exception of the wall thickness, the test results will allow SGN to make a preliminary assessment of the suitability of the pipe material in the LTS for hydrogen service. Work Package 2: Technical support for Material Testing and Analysis (PIE)Direct technical support and desktop studies will be provided, as detailed below, in collaboration with Strathclyde University for Material Testing and Analysis. The work package addresses the effect of hydrogen on line pipe steel and how that might affect the failure frequency of pipelines transporting hydrogen and hydrogen blends at pressures above 7 barg. Material testing is to be conducted by the Strathclyde University. Work Package 1: Material Testing and Analysis (University of Strathclyde)Phase 1: Material CharacteristicsPrior to the commencement of the testing programme, the pipe material of both sections on each side of the weld and the weld will be characterised in terms of the chemical composition and microstructure. These tests will ensure that the material is “as expected” and compliant with the standards at the time of manufacture of the pipeline. The information will also allow comparison of the test results with literature regarding the expected material response to hydrogen.Phase 2: Assessment of Material PropertiesThe tests proposed in this work package are intended to answer the research question - what will the effect on the tensile and fracture properties be when the material is exposed to a hydrogen environment? To answer this question, tensile tests and fracture toughness tests will be conducted for each material before and after exposure to hydrogen. This data will provide information regarding whether the exposed pipe material is acceptable in terms of ductility and/or fracture toughness. Work Package 2: Technical support for Material Testing and Analysis (PIE)Phase 1: The effect of H2 on fracture propagation control:establish bounds on the decompression behaviour of H2 and blends, through decompression calculations using REFPROP (GERG-2008), GASDECOM or similar (noting that H2 is expected to exhibit less severe decompression behaviour, as implied by Aihara et al., 2008, 2010, Botros & Kondo, 2016);determine whether or not the Charpy V-notch impact energies specified in LX/1, etc. (the contemporaneous British Gas specifications) are sufficient for H2 and blends, subject to the assumption that H2 does not affect the fracture propagation transition temperature or the upper shelf Charpy V-notch impact energy.The effect of H2 on fatigue crack growth:establish the effect of H2 on the remaining fatigue life of pipelines and associated assets due to pressure cycling, based on the literature on its effect on the rate of and the threshold for fatigue crack growth (noting that Equation (1) in ASME B31.12 is only applicable to R < 0.5, whereas the default assumption for welded joints is R ≥ 0.5), and using historical pressure cycling data, as available;establish the effect of H2 on the significance of other sources of fatigue loading in pipelines and associated assetsThe effect of H2 on flaw acceptance criteria (corrosion, mechanical, damage, welding defects, etc.): establish, based on prior work, what additional failure modes need to be considered, e.g. hydrogen cracking or HIC;establish, based on prior work, what time-dependent degradation (growth) mechanisms need to be considered, e.g. fatigue;establish, based on prior work and the mechanical testing, the effect of the changes in the toughness of the steel on the acceptance criteria for corrosion, gouges, etc. (blunt and sharp defects);define revised acceptance criteria;contribute to the updates to P/11, PV/11 and P/18 The objectives of this work are to evaluate the effects of hydrogen on vintage line pipe steels based on prior work and material testing completed on a line pipe steel similar to the Granton to Grangemouth pipeline.

The hydrogen economy can be expected to play a significant role in delivering net zero emissions in the UK by 2050. This will require the production of large volumes of hydrogen[AC1

02/11/22