Effect of Hydrogen Gas on Mechanical Properties of Pipe Metal of Main Gas Pipelines

In this article, literature data on the effect of hydrogen gas and methane-hydrogen mixtures at high pressure on the metal of gas pipelines are reviewed. The properties of low-alloy ferritic steels are known to be affected due to hydrogen embrittlement: ductility and fracture toughness decrease along with the increasing rate of fatigue crack propagation (da/dN); metal deformation curve transforms with failure mode changing to quasi-spalling. The conventional mechanical tests for evaluating hydrogen embrittlement are considered. The chemical composition and microstructure of pipe steels having strength grades from X52 (K50) to X100 (K80), characteristic of investigated materials, are shown. On the basis of published data, the effect of the hydrogen content in the methane-hydrogen mixture (from 0 to 100%), the pressure of the gas medium (up to 30 MPa), and durability on the plasticity (RRA, %; δ, displacement) and fracture toughness (K_IH) of metal was assessed. General influence patterns associated with the structural type and characteristics of pipe metal on its properties when subjected to hydrogen are presented.