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Projects: Projects for Investigator
Reference Number	NIA_NGGT0180
Title	NTS Materials Testing to Enable Hydrogen Injection in High Pressure Pipelines
Status	Completed
Energy Categories	Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas) 10%; Hydrogen and Fuel Cells(Hydrogen, Other infrastructure and systems R&D) 90%;
Research Types	Applied Research and Development 100%
Science and Technology Fields	ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 100%
UKERC Cross Cutting Characterisation	Not Cross-cutting 100%
Principal Investigator	Project Contact No email address given National Grid Gas Transmission
Award Type	Network Innovation Allowance
Funding Source	Ofgem
Start Date	01 December 2021
End Date	30 April 2023
Duration	ENA months
Total Grant Value	£1,026,641
Industrial Sectors	Energy
Region	London
Programme	Network Innovation Allowance
Investigators	Principal Investigator	Project Contact , National Grid Gas Transmission (100.000%)
Web Site	https://smarter.energynetworks.org/projects/NIA_NGGT0180
Objectives	ACTIVITY 1 – Material TestingThe proposed material test program will incorporate the following: Fracture toughness testing of Grade X52 and X65 materials in a high-pressure hydrogen environment Fatigue crack growth rate testing of Grade X52 and X65 materials in a high-pressure hydrogen environment In each case, tests will be carried out on parent pipe, seam weld and girth weld, to generate material property data similar to that generated for Grade X60 pipe, in work carried out earlier this year.  Tests will be carried out in 100% hydrogen at a pressure of 1400 psia (96.5 bara). Previous work has shown that tests at this pressure in both 20% hydrogen and 100% hydrogen exhibit a significant loss of toughness, and acceleration in fatigue crack growth rate, in comparison to behaviour in air. Material property data for the 100% hydrogen case will be bounding and provide a good basis for corresponding pipeline design calculations.  Test procedures will be based on those described in ASME VIII Section 3 Article KD-10. This includes: Fracture toughness testing. Article KD-10 stipulates that these tests should be carried out under conditions of either constant load or constant displacement, and that the value of KIH is then derived from the selected value of load (or displacement) applied to the specimens (assuming that no significant crack growth is observed. Tests carried out earlier this year, were instead carried out under slow strain rate rising load conditions, which allows a more efficient determination of fracture toughness from just a single test specimen per condition, and provides a means of establishing a conservative lower bound estimate for the fracture toughness of material in hydrogen environment. KD-10 also requires triplicate tests to be carried out, which has a large effect on the scale of test programme needed to qualify materials. In this work, a pragmatic approach is proposed to generate lower bound fracture toughness data, by carrying out screening tests on all materials and welds using just single specimens. Additional tests will then be carried out to provide triplicate results for the two lowest toughness materials. The test matrix will therefore consist of the following: o K-rate sensitivity tests to determine fracture toughness at 3 different rates, for the two parent materials (total 6 tests). The results of these tests will be used to select the K-rate for subsequent tests. o Material screening tests to determine fracture toughness of all 10 combinations of material and weld position, using single specimens (total 10 tests). Material and weld position combinations are as follows: § X52 parent material § X65 parent material § X52 seam weld, weld centre § X65 seam weld, weld centre § X52 seam weld, heat affected zone § X65 seam weld, heat affected zone § X52 girth weld, weld centre § X65 girth weld, weld centre § X52 girth weld, heat affected zone § X65 girth weld, heat affected zone o Additional tests to provide triplicate data on the worst two materials or weld positions (additional 4 tests) o A costed option to provide full triplicate testing on all material combinations is also provided (additional 16 tests) Fatigue crack growth rate testing. Again, a pragmatic approach is proposed, to generate data for a wide range of materials and weld positions, with additional tests then carried out on the worst cases. The proposed test matrix is as follows: o Frequency scanning tests to generate fatigue rack growth rate data for the two parent materials at different cyclic loading frequencies (2 tests). Previous tests have shown that the fatigue crack growthrate is relatively insensitive to this parameter over the range 0.1-0.001 Hz. The results will be used to confirm cyclic loading frequency for the following tests. o Material screening tests to determine Paris law fatigue crack growth data for all 10 combinations of material and weld position, using single specimens (total 10 tests). Material and weld position combinations are the same as above. o Additional tests to provide triplicate data on the worst two materials or weld positions (additional 4tests) o A costed option to provide full triplicate testing on all material combinations is also provided (additional 16 tests) ASME B31.12 requires triplicate tests to be carried out on the base metal, weld metal and HAZ of all materials to determine KIH in accordance with Article KD-10 of ASME VIII Section 3. The lowest value of KIH is then used in pipeline design analyses. Similarly, fatigue testing in accordance with Article KD-10 requires the testing of triplicate specimens of each material and weld position. This leads to a large matrix of tests to cover all combinations. The proposed test matrix in Task 1 seeks to reduce the total number of tests by carrying out screening tests to select the worst materials, so that triplicate tests are only carried out on these. As the pipeline design will be governed by these data, this is considered a reasonable approach, as triplicate tests will be carried out where they are most needed. However, the requirements of ASME B31.12 will not be met in full, as the requisite number of tests will not have been carried out. If a full matrix of tests is considered necessary, DNV can undertake these at additional cost, so a separate optional task is defined for this purpose. If necessary, the results of tests in Task 1 could be reviewed prior to making a decision on the need for additional tests. This task also includes additional testing of X60 material to bring the number of tests carried out up the triplicates required by ASME B31.12. It is assumed that additional material can be provided for such tests as required. ACTIVITY 2 – Data Analysis and Design The data generated above will be used to determine suitable values of KIH for use in subsequent pipeline design calculations, e.g. for determination of MAOP. A Paris fatigue crack growth law will also be derived for use in pipeline fatigue life calculations. Design calculations will be carried out for the FutureGrid pipe in accordance with ASME B31.12 and the draft supplement to IGEM-TD-1 for repurposing of NG pipelines to hydrogen service. Sensitivity analyses will also be carried out in some areas where the draft has attracted significant comment, i.e. in the definition of design factors, material performance factors, S-N curves or crack growth laws for determination of fatigue life, and the use of hydrotest as a means of ensuring freedom from defects which might reach a critical size in service. The objective of this task is therefore to use the data generated in Task 1 to carry out a set of design sensitivities to explore the impact of different design approaches. The methods defined in ASME B31.12 and IGEM-TD-1 will be used as a baseline, to establish an appropriate MAOP for the FutureGrid facility. The work will focus on materials of grade X52 and X65 as these are the materials of interest for the FutureGrid facility. Measurement Quality Statement The measurement approach used to meet Data Quality objectives will be through the use of relevant standards and their required statistical evidence to prove the results are accurate. This is described in further detail above.Data Quality StatementThe relevant data and background information will be stored for future access within the National Grid Innovation Sharepoint site.  The NTS delivers 900 TWh of natural gas energy to homes, industry and for power generation; this project aims to demonstrate that natural gas can be replaced with low-carbon hydrogen which will be a major step for enabling the UK to meet its 2050 net-zero emission target. The Health and Safety Laboratory has previously carried out an initial study on the impact of hydrogen and highlighted impacts such as leakage, venting and the effects on the mechanical properties of many materials.Several other desktop studies have been undertaken through the HyNTS programme of work which have identified the potential for hydrogen in the NTS. However, gaps in knowledge still exist which are fundamental to, and underpin, the demonstration of a safe and reliable repurposing of the National Transmission System to transport hydrogen. The HyNTS FutureGrid programme of work will address these knowledge gaps. This project relates to the testing the NTS materials to enable testing at high pressure with hydrogen. The objective of this project is to determine the capability (fracture toughness and fatigue resistance) of the national transmission systems pipeline materials in a hydrogen environment, this will enable further test work at the FutureGrid facility and the potential to inject hydrogen into the NTS at high pressure.
Abstract	This project will deliver an evaluation of X-52 and X-65 line pipe decommissioned from the NTS and to be used to construct the FutureGrid facility when injected with hydrogen, including realistic seam welds and girth welds. The tests will determine fracture toughness and fatigue crack growth rates in the material when containing 100% hydrogen which is an essential requirement for the ASME B31.12 standard to allow the planned FutureGrid test programme to be performed at NTS pressures and following that online trials of hydrogen injection into the NTS.
Publications	(none)
Final Report	(none)
Added to Database	14/10/22