卧式容器鞍座压应力的影响因素分析

Influencing Factors on Compression Stress on Horizontal Vessel Saddles

为了深入了解卧式容器中由于温度变化引起圆筒体伸缩时支座腹板与筋板组合截面上的压应力的特征,对NB/T 47042—2014标准中的应力计算公式进行分析讨论。根据力学相关理论,在鞍座截面其他尺寸确定时,将鞍座抗弯截面系数对压应力的影响转化为筋板宽度对压应力的影响。通过个案分析推导出鞍座高度、筋板宽度与截面压应力之间的定量关系式,反映了鞍座截面压应力既随着鞍座高度增加而非线性地增大,也随着筋板宽度的增加而非线性地减小。通过对不等高双鞍座中滑动鞍座压应力的分析,发现把其底板平面设计成与设备的轴线相平行时,其受力状况更加合理。最后对4种特殊结构鞍座的压应力计算方法提出意见。

A stress calculation formula given in NB/T 47042-2014 was discussed in order to analyze the compression stress on the mating face between the web plate and rib plate of saddles when the shell expands or shrinks in axial direction with the change of temperature. The pertinent mechanics theory states the influence of the bending modulus of saddles on the compression stress can be transformed to the influence of the rib width on the compression stress when the other dimensions of saddles have been set up. The derived quantitive relationship of saddle height and rib width with the compression stresses reveals the compression stress not only increases non-linearly with the increasing of saddle height but also decreases non-linearly with the increasing of rib width. The analysis on the compression stress on the moving saddle of unequal-height double-saddles finds out the loading is more reasonable when the bottom plate of saddles is parallel to the axial line of vessels. At last, the paper discusses how to calculate the compression stress on four saddles in special structures.