Research status of corrosion environment failure and safety assessment of pipeline welded joint

Pipeline transportation is an economical, safe, and efficient transportation method for transporting oil, natural gas, mineral slurry, and other fluids.Welding is the most critical construction process in pipeline engineering and is crucial in the safe operation and service of an entire pipeline system.Theoretically, the girth welded joint is the weakest link in a pipeline system.The unevenness of the structure and performance of the joint caused by welding frequently results in the failure of the welded joint before the failure of the base material of the pipe body, causing the pipeline to leak or even break.For steel pipes used in an acidic corrosive medium environment, the integration of the corrosive medium and mechanical load will accelerate the failure of the welded joint.This article reviews the failure modes of pipeline welded joints in acidic corrosive media, including stress corrosion cracking, hydrogen-induced cracking, and corrosion fracture, and corrosion fatigue considering the diffusion and accumulation of H;at the crack tip.It also reviews service pipelines in acidic corrosive media.The general processing technology of pipe joint engineering critical assessment(ECA) is investigated to provide a reference for the future development of technology in this field.

Engineering critical assessment on welding flaws of the X65 UOE girth weld based on CRACKWISE

Focused on the girth weld of a φ762 x 28.6 mm （X65） offshore UOE pipe, the fracture toughness properties at different weld joint positions were tested. Meanwhile,the largest size of different cracks under service condition was calculated by using CRACKWISE. The service life of the UOE pipe with postulated crack-like flaws was calculated by considering various fatigue factors, such as vibrations caused by ocean current and fluctuations of inner pressure. The assessment process and results can be used to direct the repair of weld flaws laid in pipes or to assess the reliability of in-serving pipes.

Reply to Shanmugam,G.“Review of research in internal-wave and internal-tide deposits of China:Discussion”

We are glad to know that our paper ＂Review of research in internal-wave and internal-tide deposits of China＂ （Gao et al., 2013） published in Journal of Palaeogeography has attracted close attention of international peers, and we noted that Shanmugam has provided a critical assessment of our paper. He claimed that ＂interpretations of ten ancient exam- ples in China and one in the central Appalachians （USA） as deep-water deposits of internal waves and internal tides are unsustainable＂, among many other comments and criticisms, and he concluded that ＂any interpretation of ancient strata as deposits of internal waves and internal tides is premature＂. This article is aimed at responding to his major criticisms. We believe that constructive discussions will benefit the development of the study in internal-wave and internal-tide deposits. Unfortunately, Shanmugam seems not to follow this line of scientific criticism, but is trying to reject all research results in this subject based on his illogical and inconsistent reasoning, and distortion of others＇ points of view. In this article, with facts and evidences, we will refuse the main wrong assertions of Shanmugam＇s, for example, ＂the use of bidirectional cross-bedding as evidence for deposition by baroclinic currents in outcrop studies is sedimentologically erroneous ＂ and ＂any interpretation of ancient strata as deposits of internal waves and internal tides is premature＂. We will also use typical characteristics of the ancient examples to demonstrate that they are certainly not turbidites, or contourites, or tsunami-related deposits, but internal-wave and internal-tide deposits as the most plausible to defend the rationality of our interpretation in our previous papers.