基于热点应力法和结构应力法的保温支撑圈焊接接头疲劳评估及对比

Fatigue Analysis and Comparison of Welded Joints of Insulation Support Ring Based on Hot Spot Stress Method and Structural Stress Method

针对疲劳容器中保温支撑圈与壳体的焊接接头,分别采用欧盟压力容器标准EN 13445-3中基于外推的热点应力法和美国压力容器标准ASMEⅧ-2中的结构应力法对其进行疲劳评估。结果显示,采用热点应力法计算的疲劳寿命大于结构应力法计算的疲劳寿命,但两者均远远小于设备壳体母材金属的疲劳寿命。当设备预期压力循环次数较多时,为满足保温支撑圈焊接接头的疲劳寿命而将壳体薄膜应力降至非常低的水平,会导致壳体材料的较大浪费,因此,在循环次数较高的疲劳设备中应尽量采用非焊接保温支撑方式,或是采用其他受力较好的焊接保温支撑圈结构。

For welded joints of thermal insulation support ring and shell in fatigue vessels,the hot spot stress method based on extrapolation in European pressure vessel standard EN 13445-3 and structural stress method in American pressure vessel standard ASME Ⅷ-2 were used for fatigue assessment.The results show that the fatigue life calculated by the hot spot stress method is greater than that calculated by the structural stress method,but both are far less than the fatigue life of the base metal of the equipment shell.When the equipment is expected to have a large number of pressure cycles,in order to meet the fatigue life of the welded joint of the insulation support ring,the shell film stress is reduced to a very low level,which will lead to a large waste of the shell material.Therefore,in the fatigue equipment with a high number of cycles,non-welding insulation support mode should be used as far as possible,or other welding insulation support structures with better forces should be used.