管道附加载荷在容器上产生应力的正确评定——压力容器应力分析设计中的六个重要问题(三)

REASONABLE ASSESSMENT ON THE STRESS ON PRESSURE VESSELS CAUSED BY PIPELINE ADDITIONAL LOAD——SIX IMPORTANT ISSUES ABOUT STRESS ANALYSIS DESIGN FOR PRESSURE VESSELS(Ⅲ)

从跟随效应出发,阐述了容器管口对管道附加载荷作用下的应力不以一次应力控制,则跟随效应必然发生。跟随效应发生后,必须对整个管道和容器系统进行安定分析。然而现今按管道专业提供的载荷(力的形式)对容器管口进行安定分析是无效的。当管道专业向容器专业提供的管道附加载荷是以力的形式给出时,容器专业在进行容器应力分析时,应力必须以一次应力加以控制。只有将整个管道和与之相连的容器连为一整体,施加管道热载荷后一并进行安定性分析,其时容器中的应力方能以二次应力加以控制。

Starting from following effect,this paper clarifies that following effect will be bound to happen if stress by pipeline additional load caused by piping applying on pressure vessels isn't evaluated as primary stress.Shakedown analysis on the whole piping and vessel system must be carried out after following effect happens.But it's invalid that shakedown analyses about nozzles on pressure vessels are in accordance with loads provided by piping discipline as a form of force at present.Stress must be evaluated as primary stress when loads caused by piping provided by piping discipline are given as the form of force and stress analysis about pressure vessel is carried out by vessel discipline.Only when piping and vessel fit together as a whole,on which thermal loads are applied and then shakedown analysis is carried out,can stress in pressure vessels be evaluated as secondary stress.