Localized erosion is one of the most common failure mechanisms associated with boiler tubes, driven by impaction of the tube surface by fly ash, soot blowing steam, falling slag or other abrasive substances from the boiler’s combustion chamber. The tubes may experience significant localized reduction in their wall thickness, becoming susceptible to plastic collapse and bursting. The replacement of failed tubes is one of the leading causes of unplanned and forced boiler outages in process and power plants. In this study, geometric functions to enable the accurate modelling of boiler tubes with localized erosion flaws were developed from conceptualized models and finite element analyses were conducted on the modelled flawed tubes. The effect of geometry on the stress concentration in the tubes and on the failure pressure associated with the tubes was investigated. Linear elastic stress analysis is sensitive to the flaw geometry – for a representative problem stresses vary 38% as the flaw shape is varied. However, nonlinear elastic-plastic analysis shows significantly reduced sensitivity to flaw shape. The collapse pressure of the same representative problem now varies only 2.45% as the flaw shape is varied. This finding was demonstrated for various failure thresholds sourced from the literature, based either on plastic strain or Von Mises equivalent stress, which demonstrates that the failure of the tubes is insensitive to the specific choice of shape parameterization, as long as the minimum remaining wall thickness is matched. The outcome of these investigations gives further insight into the behaviour of tubes with localized external flaws while in service.

局部腐蚀是与锅炉管相关的最常见的故障机制之一，其受飞灰，吹灰蒸汽，掉落的炉渣或来自锅炉燃烧室的其他磨料撞击管表面所驱动。管的壁厚可能会发生局部局部减小，变得容易发生塑料塌陷和破裂。更换故障管是导致过程和发电厂计划外和强制锅炉停机的主要原因之一。在这项研究中，通过概念化模型开发了几何函数，以实现具有局部腐蚀缺陷的锅炉管的精确建模，并对建模的缺陷管进行了有限元分析。研究了几何形状对管中应力集中以及与管相关的破坏压力的影响。线性弹性应力分析对缺陷的几何形状很敏感–对于代表性的问题，应力随着缺陷形状的变化而变化38％。但是，非线性弹塑性分析显示出对缺陷形状的敏感性大大降低。现在，随着缺陷形状的变化，同一代表性问题的崩溃压力仅变化了2.45％。基于塑性应变或冯·米塞斯当量应力，从文献中得出的各种破坏阈值都证明了这一发现，这表明，只要最小剩余壁厚，管子的破坏对形状参数化的特定选择不敏感。被匹配。