[ storage ]
Various tests are currently being conducted at the site as part of a technology qualification program developed according to DNV-recommended practices for the qualification of innovative technology . Vallourec is also undergoing the approval program for the equipment to comply with the EU Pressure Equipment Directive ( PED ) and the American Society of Mechanical Engineers ( ASME ) code in the United States .
Tests in Aulnoye-Aymeries were initiated with a mixture of hydrogen and nitrogen before progressing to pure hydrogen . Pressure was held at 280 bar for several months to ensure meticulous measuring of potential leakage and to ensure that containment tubes were safe and fully hydrogen-tight . Once tests were able to rule out leakage , various additional tests were subsequently launched and are still ongoing . They include pressure cycles , filling and emptying conditions , maintenance and re-testing conditions ( including an onsite hydrotest ), emergency shutdown scenarios , etc .
This program will run until Q3 2024 . It provides evidence of the high safety performance of the system and is instrumental in the validation of this new technology .
Adapting tubular vessels to the specificities of hydrogen
To design such safe and long-lasting storage systems , Vallourec calls upon its core areas of expertise .
A major risk is the hydrogen embrittlement of metal pipes , which can put at risk the structural integrity of equipment and infrastructure . This is a phenomenon that Vallourec ’ s teams have studied for a long time . In particular , they have explored the development of suitable products for resistance to sour corrosion driven by hydrogen sulfide ( H 2
S ), a strong promoter of hydrogen absorption in metal .
By drawing on existing knowledge of material resistance and sour corrosion resistance , the best alloys were chosen to resist hydrogen embrittlement . This experience and the corresponding product portfolio were leveraged to conduct a research program dedicated to dihydrogen ( H 2
) service , including fracture toughness ( FT ) and fatigue crack growth rate ( FCGR ) experimental tests . 7 Combined with Vallourec ’ s deep expertise of metallurgies ( chemistry , microstructure , mechanical properties ), this experience informed the selection and validation of appropriate material for use in hydrogen storage vessels . Notably , the proprietary steel grade VM110SS was chosen , designed for sour service and resistant to high corrosion .
Similarly , Delphy technology relies heavily on the ability to tightly connect pipes to each other , using unique premium mechanical connections . While conventional – and extensive – leak test programs have been conducted with helium as the leak tracer , Vallourec concluded that tests with hydrogen gas were needed to ensure hydrogen tightness .
The teams pioneered a fit-for-purpose testing program . The test program was performed in fullscale in 9 – 5 / 8 ” 47.00 ppf L80 on Vallourec ’ s latest generation of advanced premium connections . It covered pressure and temperature cycles as well as mechanical loads ( tension , compression ) to represent the conditions expected in operations . Lab tests were complemented by simulation by finite element analysis to expand the results to cover other configurations that are less critical in terms of tightness . Overall , the assessment of hydrogen sealability performance showed very positive results , which made it possible to employ this technology for the Delphy hydrogen storage system . Test results from the demonstrator confirm the excellent tightness in operation .
In terms of size , 10 ¾-inch tubes were used , with a target of higher ranges , from 14 to 16 inches ,
Hydrogen Tech World | Issue 17 | August 2024 21