压力容器制造误差探究

Research on Manufacturing Error Like Pressure Vessel

大型化工容器快冷器制造过程中出现了筒体轴向严重收缩现象。通过详细分析设计图、施工工艺、焊接工艺评定和质保体系运行过程,得知奥氏体不锈钢板材的高收缩率是导致容器制造误差的根本原因。除此之外,容器壳程由多段筒节组焊而成,轴向收缩进一步累积;筒节之间组对装配时强制变形使得轴向应力远大于环向应力,促进了壳程轴向收缩;板厚12mm的筒体通过焊条电弧焊四层焊满,层间温度总是处在100～350℃范围的高位数值上,对焊缝及热影响区不充分的弹性膨胀和强有力的塑性收缩起到了推波助澜的作用,加剧了各条环焊缝的轴向收缩。

The serious axially shrinkage of the cylinder is appeared during manufacturing process of rapid cooling vessel of large chemical containers.By the detailed analysis of design drawing,manufacturing process,WPQ and the operation process of quality assurance system,it is known that the high shrinkage percentage of austenitic stainless steel plate is the fundamental cause of manufacturing error of the pressure container.In addition,the container shell is welded by a number of shell ring joints,and axial contraction is further accumulated;the axial stress is greater than the annular stress due to the forced deformation in assembly process of two cylindrical shell section,so that axial contraction of shell surface is promoted;the 12mm thick shell is welded in four layer by SMAW,which inter layer temperature is always on the high value range of 100-350℃ ,thatpromotesinadequate elastic expansion and strong plasticshrinkageinweld and heat affected zone,the axial contraction of each girth weld is intensified.