• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文会议>International pipeline conference >GIRTH WELD ECA FROM THE PERSPECTIVE OF CODE REVISIONS IN NORTH AMERICA
【24h】

GIRTH WELD ECA FROM THE PERSPECTIVE OF CODE REVISIONS IN NORTH AMERICA

机译：从北美的代码修订角度的束缚焊接ECA

获取原文
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In North America there are two primary girth weld ECA (Engineering Critical Assessment) codes: API 1104 Appendix A and CSA Z662 Appendix K. Both codes were developed in the early- to mid-1980's and thus represent the technology of that time. Significant progress has been made since then in understanding the structural behavior of girth welds containing welding defects. This paper describes an effort funded by the PRCI (Pipeline Research Council International) to establish the technical basis for the revisions of these codes using the knowledge generated since the inception of the codes. The CSA Z662 Appendix K sets defect tolerance using separate fracture and plastic collapse criteria, while API 1104 Appendix A has only a fracture criterion. The worldwide trend in defect assessment is moving towards FAD (Failure Assessment Diagram) based approach, by which both fracture and plastic collapse can be assessed in one consistent format. An FAD-based ECA procedure specifically tailored to girth welds has been developed in a separate PRCI-funded project. This procedure incorporates refined fracture and plastic collapse solutions and the effects of weld strength mismatch. The experimental verification has shown that the procedure is accurate and can become the basis for future code revisions. As an interim step towards the eventual adoption of a fully FAD-based approach, a number of revisions may be made to the API 1104 Appendix A, including (1) adding a plastic collapse criterion; (2) lowering the minimum CTOD requirement of using Appendix A to 0.003 inch (0.076 mm) from the current minimum of 0.005 inch (0.127 mm); (3) setting the allowable defect length as a continuous function of defect depth (height for buried defects); (4) allowing the use of any valid CTOD toughness greater than a set minimum value; (5) revising the notching procedure for HAZ CTOD testing. These recommendations are interdependent. Selectively adopting any of those recommendations may result in undesirable consequences. For instance, lowering minimum CTOD requirements necessitates the revision of allowable defect height. Adding the plastic collapse criterion would almost certainly require the change of defect length allowance of the fracture criterion from the current step function to a continuous relation. It should be made absolutely clear that lowering the minimum CTOD requirements for using Appendix A does not mean inferior weld quality control. It merely allows the assessment of significance of weld defects using the fracture mechanics methodology that has been proven effective. The interim step for the CSA Z662 Appendix K is revising the plastic collapse criterion. These revisions, when implemented, should result in more consistent degree of conservatism than the current codes. In certain cases, the size of the allowable defects is less restrictive than the current codes while maintaining consistent and adequate safety margin. This should translate to cost savings in both new construction and the maintenance of existing pipelines without sacrificing the safety and integrity of the pipelines.
机译：在北美有两种主要环绕焊接ECA（工程批判性评估）代码：API 1104附录A和CSA Z662附录K.这两个代码都在早期到1980年中期，因此代表了该时间的技术。从那时起，已经在理解含有焊接缺陷的周长焊缝的结构行为的情况下取得了重大进展。本文介绍了由PRCI（管道研究理事会国际）资助的努力，以利用自代码成立以来所产生的知识来确定这些代码的修订的技术基础。 CSA Z662附录K使用单独的骨折和塑料塌陷标准设置缺陷容差，而API 1104附录A只有骨折标准。缺陷评估的全球趋势正在朝着基于FAD（失败评估图）的方法，通过该方法可以以一种一致的形式评估骨折和塑性坍塌。在一个单独的预计项目中开发了一种专门针对周长焊接量身定制的基于FAD的ECA程序。该过程包括精制骨折和塑料塌陷解决方案以及焊接强度不匹配的影响。实验验证表明，该程序准确，可以成为未来代码修订的基础。作为朝向最终采用基于FAD的方法的临时步骤，可以对API 1104附录A进行许多修订，包括（1）添加塑料塌陷标准; （2）降低使用附录A至0.003英寸（0.076 mm）的最小CTOC要求，从最小值为0.005英寸（0.127 mm）; （3）将允许的缺陷长度设定为连续缺陷深度的持续功能（埋藏缺陷的高度）; （4）允许使用任何有效的CTOD韧性大于设定的最小值; （5）修改HAZCTOD测试的缺口程序。这些建议是相互依存的。选择性地采用任何这些建议可能会导致不良后果。例如，降低最小CTOD要求需要修改允许的缺陷高度。添加塑料塌陷标准几乎肯定需要从电流阶跃函数到连续关系的裂缝标准的缺陷长度允许的变化。它应该绝对清楚，降低使用附录A的最小CTOD要求并不意味着劣质焊接质量控制。它仅允许评估焊接缺陷的重要性，使用已被证明是有效的裂缝力学方法。 CSA Z662附录K的临时步骤正在修改塑料塌陷标准。在实施时，这些修订应导致比当前代码更加一致的保守度。在某些情况下，允许缺陷的尺寸比当前代码的限制较小，同时保持一致和充分的安全余量。这应该转化为节省新的建设和现有管道的维护，而不牺牲管道的安全性和完整性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号