Influence of long-term operation on the properties of main gas pipeline steels. A review

Underground pipelines during operation are affected by mechanical and corrosive factors. The susceptibility of cathodically protected pipe to hydrogen degradation increases, which contributes to stress-corrosion cracking. It is believed that the main factor in pipeline steels degradation is deformation aging, which increases strength and reduces plasticity. Volume microdamages also develop in long-time exploited steels. But in many cases, the base metal and welded joints of long-term operated pipelines retain satisfactory performance. Due to the high value of viscosity and plasticity of the metal in an as-received state, the metal state of long-term operated gas pipelines can be considered satisfactory

Закономірності стрес-корозійного розтріскування трубної сталі 09Г2С при катодній поляризації в модельному ґрунтовому середовищі

Peculiarities of corrosion-mechanical fracture of 09G2S pipe steel samples in the conditions of cathodic protection were investigated. It was established that depending on the level of protective potential, stress-corrosion cracking of pipe steel of a ferrite-pearlite class 09G2S can occur by different mechanisms. The range of protective potentials was determined, at which the anodic dissolution and hydrogen embrittlement occur simultaneously during the fracture of steel, namely from -0.85 V to -1.0 V. The existence of the above mechanisms is confirmed by the change in the strength and viscosity properties of the steel and the morphology of the fractures. For steels of other manufacturing technology and grades, these potential areas may differ.Досліджено особливості корозійно-механічного руйнування зразків труби 09Г2С в умовах катодного захисту. Встановлено, що в залежності від рівня захисного потенціалу, корозійно-корозійне розтріскування трубної сталі феритно-перлітового класу 09Г2С може відбуватися різними механізмами. Визначено діапазон захисних потенціалів, при якому анодне розчинення та водневе окрихчення відбуваються одночасно під час руйнування сталі, а саме від -0,85 В до -1,0 В. Наявність вищезазначених механізмів підтверджується зміною міцності та в'язкостних властивостей сталі та морфологією руйнування. Для сталей інших технологій виробництва та марок ці області потенціалів можуть відрізнятися

Characterizing physiological status in three breeds of bulls reared under ecological and climate conditions of the Altai region

Ecological and climatic factors have an impact on the health, productivity and reproduction of the cattle. The goal of this work is the study of physiological status of servicing bulls reared under ecological and climate conditions of the Altai region, by defining the differences between Red-Steppe, Simmental and Black-and-White breeds in spermatogenic, hormonal, biochemical and hematological parameters. Samples of peripheral blood and ejaculates were taken from 48 grown-up servicing bulls (average age 5.6±0.3 years) in autumn period. It was established that Red-Steppe bulls have higher concentrations of nonorganic phosphorus, leucocytes, erythrocytes, hemoglobin, hematocrit and erythrocyte sedimentation rate in comparison with animals of Simmental breed, and the hemoglobin concentration and hematocrit are also higher in comparison with Black-and-White breed. It was noted that bulls of Black-and-White breed have a higher level of cortisol in comparison with the other breeds. The lowest level of serum urea and total protein and increased serum activity of creatine kinase and γ-glutamyl transferase, as well as the heaviest body weight were observed in Simmental breed bulls. The differences between breeds in a wide spectrum of physiological measures reflect not only genetically determined peculiarities of homeostatic mechanism, but also may reflect different ability to adapt to local ecological and climate conditions of the Altai region. Spermatogenic, biochemical and hematological measures in bull sires reared in the Altai region were similar to those in bulls bred in other Russian regions and some other countries. The measures reported could serve as reference values and therefore represent ‘normal’ values of physiological status for these bull sires reared in this ecological and climatic zone, but could be utilized in further studies for comprehensive monitoring of cattle breeding stock in other ecological and climatic zones of the Siberian region of Russia