Application of the various methods for assessment of in-service degradation of pipeline steel
Olha Zvirko, B. G. Mytsyk, H. М. Nykyforchyn, Oleksandr Tsyrulnyk, Ya. Kost
Abstract
The paper presents the research results on assessment of in-service degradation of the 0.17 C-Mn-Si steel of gas transit pipeline operated for 36 years. High degradation degree of the operated steel was manifested in a significant decrease in plasticity characteristics, impact toughness and resistance to stress corrosion cracking and hydrogen embrittlement compared to the as-delivered steel. The tests carried out using the low stress method revealed significant changes in elastic hysteresis, elasticity modulus and relative residual deformation of the steel depending on its state (as-delivered and post-operated ones), demonstrated to be highly sensitive to assess in-service degradation degree of pipeline steels.