Principles of Metallurgical Design for Strain-based Design Regulated X100 Line-pipe Steel -- A Tough Challenge to Fracture Propagation Control Strategy for Gas-pipeline Integrity
- 作者：Xiaobing (Edward) Wu
- 会议时间：2013-09-16
- 关键词：X100 ; Metallurgical design ; As-received ; Line-pipe ; Microstructural features ; Strain-based design ; Strain-aging ; Optimum balance ; Toughness ; Strain-capacity ; Fracture ; Quasi-brittle ; Degradation ; Propagation ; Far Northern Region
- 母体文献：2013油气田监测与管理联合大会论文集
- 会议名称：2013油气田监测与管理联合大会
- 会议地点：西安
- 主办单位：中国石油学会
- 语种：chi
摘要
In order to cope with stringent loading environment in the Far Northern Region, X100 line-pipe steel etallurgy is specially designed in obedience to the regulations of strain-based design (SBD).Owing to the combination of harsh service conditions (e.g., ground-movement inducing strain-demand) of gas-transmission pipeline and specific microstructural features (e.g., over-refined grain size and dual-phase constituent) of the steel, it is more prone to the susceptibility to strain aging (SA) and quasi-brittle fracture.This steel may lose its partial as-received mechanical properties over a long period of service.Its excellent plastic indications (e.g., strain-capacity, ductility, fracture propagation toughness) could be worse.Therefore, the "right" metallurgical design is of importance.In this paper, emphasis is placed on the principles of metallurgical design of the SBD-regulated X100 steel, along with the technical aspects that control its performance from steel-making through to long-term pipeline operation.(1) The Optimum Balance amongst high strength, sufficient toughness and appropriate weldability is a fundamental requirement for the application of X100 steel used in fields.(2) The high strain-capacity against the strain-demand is a cornerstone of SBD applied for the discontinuous permafrost.(3) The long-term serviceability against the SA-induced degradation in as-received mechanical properties is critical for the gas-pipeline integrity.(4) The adequate self cracking-arrestability against high-speed fracture propagation without an evidence of separation is the vital fracture control strategy for the catastrophe aviodance.A tough challenge to the pipe is that it may experience the quasi-brittle or even brittle fracture at an extremely high speed (over 200 m/s) in the event of an incident on the pipeline, or it may not share the same fracture mechanism at testing and pipeline-failure impact speeds.Due to the narrow technical windows in the manufacture of this steel, these principles also need to be kept in balance to one another.In addition, the issue on what type of pipe (spiral or UOE) has higher self arrest fracture toughness becomes more attractive.