Influence of Textures of Pipeline Steels after Operation on Their Brittle Fracture Resistance

Zvirko, Olha; Kret, N. V.; Tsyrulnyk, Oleksandr; Vengrynyuk, T. P.

doi:10.1007/s11003-018-0198-8

Cited by 26 publications

(11 citation statements)

References 3 publications

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“…Two main methodical peculiarities should be distinguished in the preparation of the specimens; (i) all specimens are cut transversally to the rolling direction/pipe axis, (ii) working part thickness for the flat specimens is 2 mm. The former one concerns with an essentially higher sensitivity of steel characteristics to operational degradation and hydrogen embrittlement determined on transversal specimens [23,24]. This choice is explained by the fact that operational damaging of rolled steel pipes mainly consists of microdelaminations along components of the ferrite-pearlite structure and nonmetallic inclusions elongated in the rolling direction [23,26,28] leading to such orientation of defects.…”

Section: Methodsmentioning

confidence: 99%

“…The former one concerns with an essentially higher sensitivity of steel characteristics to operational degradation and hydrogen embrittlement determined on transversal specimens [23,24]. This choice is explained by the fact that operational damaging of rolled steel pipes mainly consists of microdelaminations along components of the ferrite-pearlite structure and nonmetallic inclusions elongated in the rolling direction [23,26,28] leading to such orientation of defects. The orientation of these defects coincides with the fracture plane of transversal specimens (in contrast to longitudinal ones) facilitating the fracture processes, thus, transversal specimens are preferable for testing.…”

Section: Methodsmentioning

confidence: 99%

“…Hydrogen transportation by pipelines is assumed to intensify the metal hydrogenation for two reasons: (i) due to hydrogen dissociative adsorption [18] and (ii) an increase in the amount of electrochemically formed hydrogen [19] absorbed by the pipe wall. On the other hand, gas pipeline networks usually have been operating for a long time, which leads to the essential deterioration of initial (as-received) physico-mechanical properties of steels, mostly affecting their brittle fracture resistance [20][21][22][23][24][25][26]. In the case of hydrogen transportation, a decrease in the resistance to hydrogen embrittlement is especially important since it can cause hardly predictable pipeline failures [19,20,27].…”

Section: Introductionmentioning

confidence: 99%

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Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

Nykyforchyn

Zvirko

Hredil

et al. 2021

Frattura Ed Integrità Strutturale

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A methodology of experimental research on hydrogen embrittlement of pipe carbon steels due to the transportation of hydrogen or its mixture with natural gas by a long-term operated gas distribution network is presented. The importance of comparative assessments of the steel in the as-received and operated states basing on the properties that characterize plasticity, resistance to brittle fracture and hydrogen assisted cracking is accentuated. Two main methodological peculiarities are pointed out, (i) testing specimens should be cut out in the transverse direction relative to the pipe axis; (ii) strength and plasticity characteristics should be determined using flat tensile specimens with the smallest possible thickness of the working part. The determination of hydrogen concentration in metal, metallographic and fractographic analyses have been supplemented the study. The effectiveness of the proposed methodology has been illustrated by the example of the steel research after its 52-year operation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

Nykyforchyn

Zvirko

Hredil

et al. 2021

Frattura Ed Integrità Strutturale

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“…Pipes for transit pipelines are usually formed by rolling; therefore, a texture produced in steels after rolling in industrial processing conditions should be taken into account under the assessment of their operational degradation. In practice, this texture manifests itself by anisotropy in the mechanical properties of steel, as illustrated in Table 2 [28] for impact toughness measurements. The results showed essential differences in KCV values depending not only on the steel state (as-received vs. operated) but also on specimen orientation relative to the pipe axis.…”

Section: Deterioration Of Mechanical Propertiesmentioning

confidence: 99%

Assessment of Operational Degradation of Pipeline Steels

et al. 2021

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This paper summarizes a series of the authors’ research in the field of assessing the operational degradation of oil and gas transit pipeline steels. Both mechanical and electrochemical properties of steels are deteriorated after operation, as is their resistance to environmentally-assisted cracking. The characteristics of resistance to brittle fracture and stress corrosion cracking decrease most intensively, which is associated with a development of in-bulk dissipated microdamages of the material. The most sensitive indicators of changes in the material’s state caused by degradation are impact toughness and fracture toughness by the J-integral method. The degradation degree of pipeline steels can also be evaluated nondestructively based on in-service changes in their polarization resistance and potential of the fracture surface. Attention is drawn to hydrogenation of a pipe wall from inside as a result of the electrochemical interaction of pipe metal with condensed moisture, which facilitates operational degradation of steel due to the combined action of operating stresses and hydrogen. The development of microdamages along steel texture was evidenced metallographically as a trend to the selective etching of boundaries between adjacent bands of ferrite and pearlite and fractographically by revealing brittle fracture elements on the fracture surfaces, namely delamination and cleavage, indicating the sites of cohesion weakening between ferrite and pearlite bands. The state of the X52 steel in its initial state and after use for 30 years was assessed based on the numerical simulation method.

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“…From the results of numerous literature data [19,20,21,22] and following the results of our previous investigations of gas pipeline steels from Ukraine [15,23,24,25], one of the main reasons for the degradation of gas main pipes is related to their strain aging. It gives rise to enhanced strength and decreased ductility, see stage I in Figure 1a.…”

Section: Degradation Processes In Gas Main Steelsmentioning

confidence: 99%

Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology

et al. 2019

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Regularities of steel structure degradation of the “Novopskov-Aksay-Mozdok” gas main pipelines (Nevinnomysskaya CS) as well as the “Gorky-Center” pipelines (Gavrilovskaya CS) were studied. The revealed peculiarities of their degradation after long-term operation are suggested to be treated as a particular case of the damage accumulation classification (scheme) proposed by prof. H.M. Nykyforchyn. It is shown that the fracture surface consists of sections of ductile separation and localized zones of micro-spalling. The presence of the latter testifies to the hydrogen-induced embrittlement effect. However, the steels under investigation possess sufficiently high levels of the mechanical properties required for their further safe exploitation, both in terms of durability and cracking resistance.

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Influence of Textures of Pipeline Steels after Operation on Their Brittle Fracture Resistance

Cited by 26 publications

References 3 publications

Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

Assessment of Operational Degradation of Pipeline Steels

Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology

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