两种循环计数法及最大最小计数法在石化设备疲劳校核中的应用

Two Cycle Counting Methods and Application of Max-min Cycle Counting Method in Fatigue Assessment of Petrochemical Equipment

石化装置的设备有时会出现温度与压力均随时间变化的操作工况,需要进行疲劳校核,针对这种复杂工况的循环计数,ASMEⅧ-2附录5-B中提出了雨流法和最大最小计数法两种方法。两种方法各有特点,应用范围不同。首先介绍了两种方法的理论背景,然后采用最大最小计数法,对承受温度和压力随时间非比例变化的结构进行循环计数,最后提出此类结构应力分析时需要注意的问题,为工程人员处理相关案例提供参考。

For some equipment of petrochemical plants under complicate operating conditions,there will appear the operating conditions that both temperature and pressure change with time,and fatigue checking should be performed.For the cycle counting under such complicate operating conditions,rainflow cycle counting method and max-min cycle counting method are presented in ASMEⅧ-2,Annex 5-B.The two methods have their own characteristics,and they apply in different cases.First,the theoretical background of the two methods was introduced,and then cycle counting was performed for a structure whose temperature and pressure change non-proportionally with time using the max-min cycle counting method.Finally,the points to which attention should be paid were given in analyzing this type of structures,which provides a reference for engineers to deal with relevant cases.