浮顶罐刮蜡机构损坏的力学分析

Mechanical Analysis on the Failure of Paraffin Scraping Mechanism for Floating Roof Tank

从力学角度分析了浮顶罐刮蜡机构压簧大量断裂的原因:未按设计图安装压簧,导致其实际挠度超过设计挠度的88％,使压簧根部的最大弯矩处正应力超出了许用应力值,应力集中使压簧折角处两边产生微裂纹;罐壁焊缝及施工中遗留的凸出焊点和残留物对刮蜡板产生卡阻和冲击荷载,压簧经长时间运行后发生疲劳断裂。针对上述原因。

Discussed from the mechanics point of view are the reasons for the frequent failures of the pressure spring in the paraffin scraping mechanism for floating roof tank. The reasons are the following: (1)The pressure spring is not installed as designed, resulting in an actual bending deflection of over 88 % of the designed value,and a disallowable normal stress at the foot of spring where exists the maximum bending moment ;concequently ,the centralized stress on the pressure spring gives rise to mi-crocracks.(2)Due to the resistance and impact from the welds of shell plates and the projection welding and residues left during construction,the pressure spring may crack with fatigue after a long time period of service,specific repairing programs are given accordingly.