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Reference Number NIA_NGN_301
Title Failure Modes and Permeation Testing of PE
Status Started
Energy Categories FOSSIL FUELS: OIL, GAS and COAL(Oil and Gas, Refining, transport and storage of oil and gas) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields PHYSICAL SCIENCES AND MATHEMATICS (Metallurgy and Materials) 20%;
ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 80%;
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
Northern Gas Network (NGN) North East
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 May 2022
End Date 31 October 2023
Duration ENA months
Total Grant Value £435,226
Industrial Sectors Energy
Region North East
Programme Network Innovation Allowance
 
Investigators Principal Investigator Project Contact , Northern Gas Network (NGN) North East (99.993%)
  Other Investigator Project Contact , Wales and West Utilities (0.001%)
Project Contact , Cadent Central (0.001%)
Project Contact , Cadent Eastern (0.001%)
Project Contact , Cadent North London (0.001%)
Project Contact , Cadent North West (0.001%)
Project Contact , Cadent West Midlands (0.001%)
Project Contact , Northern Gas Network (NGN) North East (99.993%)
Project Contact , SGN - Southern England (0.001%)
  Industrial Collaborator Project Contact , Wales and West Utilities (0.000%)
Project Contact , Northern Gas Networks (0.000%)
Project Contact , Cadent Gas (0.000%)
Project Contact , SGN (0.000%)
Web Site https://smarter.energynetworks.org/projects/NIA_NGN_301
Objectives Project partners, Radius Systems, through contribution to the H100 project developed a PE testing facility for use in assuring safe conversion for PE networks. The hydrogen test facility is a unique piece of equipment designed with the specific purpose of accelerating the lifetime of polyethylene pipe and fitting systems of the type used by GDNs in their networks. It means pipe systems can be tested, in contact with hydrogen, until failures occur, the failure condition being managed to a safe state. Testing will be conducted across the follow criteria:  - Permeation testing - Slit defect leakage rate - Stress crack – plain pipe baseline effects - Stress crack – combined stresses / pre-existing damage - Stress crack – Repairs / alterations / diversions - Fracture toughness – fast fracture resistance - Leak tightness of house entry fittings Output of each testing criteria will be included in production of final reports with dissemination to relevant stakeholders, such as; IGEM, BEIS and HSE This project will review the following: Permeation is the one factor with a known negative impact on conversion to hydrogen. It has been well researched with modern materials to establish diffusion coefficients but no study has been performed on materials that are 50 years old, of the type used in the United Kingdom, to assess the influence of time dependent property changes. A safety case requirement exists to determine whether permeability through the material is affected by previous use with methane, and by time dependent stress response of the material. The wear out mode for polyethylene pipe, like fittings, will involve some form of slow crack growth mechanism and this results in brittle like cracks. To assist with a reasonable assessment of risk for actual representative defect sizes, it is proposed to age pipe in a way that induces cracking and assess the size of the resulting defect. This provides evidence to marry to third party work conducted by NGN on the effect of various defect sizes giving rise to risk from the network .In studies to date, there has been no evaluation of the effect on time to failure for polyethylene pipes in contact with hydrogen for slow crack growth. It is not known whether the reliable lifetime is shortened, or extended, versus known references (such as lifetime evaluated in contact with water which forms the baseline).  Fracture toughness continues to hold significant question marks as to whether hydrogen affects the fracture toughness of polyethylene materials, the theory indicates that for the pressure ranges used in practice it should not have an effect but previous tests have been inconclusive. This is though, a key attribute that is required to have confidence that the asset will be no more susceptible to damage, for example from a third party strike. Confidence in this attribute also informs the outcome that risk of such fractures propagating will also reduce.  Leak tightness of house entry fittings is a small item within the overall scheme of works but a key learning from the H100 project was that some creep relaxation of polymer materials supporting other plastic components and elastomeric seals is to be expected in practice. To assist in providing some evidence in relation to hot iron fittings it is proposed to conduct two forms of leak tightness testing to assist with a quantified risk assessment in this area. The project will undertake initial modelling/calculations/measurements for the items above that will provide an indication of whether the items above are suitable for hydrogen transportation instead of natural gas and make recommendations for further research/testing that may be required. The delivery of the scope above will assist in highlighting potential issues that need to be researched further and will provide input into confirming the compatibility of the existing GD networks to transport hydrogen. The repurposing the UK gas networks with hydrogen to support the challenge of the climate change act has the potential to save £46 billion with minimal gas customer disruption verses alternative decarbonisation solutions.  This proposal aims to fulfil two objectives. - It aims to address gaps in the work performed jointly with HSL in the two referenced studies (H100 and HyDeploy) which are appropriate to aged materials. - To ensure direct evidence is available for the oldest materials in the network to permit risk assessors building safety cases to provide appropriate evidence
Abstract This project is to determine the suitability of the existing PE network for 100% hydrogen conversion, addressing the knowledge gap of existing operational assets. While testing has concluded current specification PE pipework is suitable for 100% hydrogen conversion, no research has been conducted on PE subjected to prolonged exposure to natural gas under pressure, adversely effecting material properties over time, in some instances up to 50 years. This project will expand the evidence generation programme of PE assessment to include permeation testing, slit defect leakage rate, stress cracking susceptibility, fracture toughness and leak tightness of house fittings for pre-1976 specification PE.
Publications (none)
Final Report (none)
Added to Database 14/10/22