Page 7 - Дисертаця Венгринюк

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Ключові слова: трубопровід, сталь, водень, деградація, водневе

окрихчення, концентрація водню, моделювання, машинне навчання,

прогнозування, в’язкість руйнування, механічні властивості,

транспортування, тиск, дефект, тріщина

ABSTRACT

Venhryniuk O. I. Development of computational and experimental methods

for assessing the degradation of steels of gas transmission pipelines for hydrogen

transportation. – Qualifying scientific work as a manuscript.

Thesis for the degree of Doctor of Philosophy in the field of knowledge
11 – Mathematics and Statistics in specialty 113 – Applied Mathematics. – Karpenko

Physico-Mechanical Institute of the National Academy of Sciences of Ukraine,

Lviv, 2026.

The development of hydrogen energy technologies has created a growing need

to repurpose the existing Ukrainian gas transmission pipeline network for hydrogen

transportation. However, the interaction of hydrogen with pipeline steels can

significantly alter their mechanical properties and operational reliability due to
hydrogen embrittlement, which inevitably leads to a reduction in ductility and fracture

toughness. In addition, most pipelines have already been in service for prolonged
periods, often exceeding their design life, making it essential to account for service-

induced degradation of the steels. Gas transmission pipelines were originally designed
for natural gas transportation; therefore, the combined effect of hydrogen exposure

and operational degradation of pipeline steels requires the development of reliable

methods for assessing and predicting the mechanical properties of the material, as well

as substantiating criteria for its limit state during pipeline repurposing for hydrogen

transportation. By penetrating into the metal, hydrogen accelerates degradation

processes and promotes the initiation and propagation of microcracks, which may

result in sudden structural failure even under relatively low loading levels. Fracture

toughness is considered one of the most sensitive parameters for assessing the

condition of in-service metals. However, its experimental determination for pipeline