绵阳某公司一分厂水溶液全循环法15万t尿素装置在用的尿素合成塔,工厂分别在2003、2005年2次大修中对该塔进行了开塔监检,塔底进口液氨管在与球形封头焊接的长度为150mm的管段内表面上存在浅表裂纹,深度分别为2.0mm和1.0mm,长度达到5～8mm。而CO_2和一甲液(氨基甲酸铵)进口管及焊缝却也没有发现过裂纹。通过分析认为是在生产工况条件下受温差应力的长期影响而出现造成的,本文通过应力计算核定,印证了笔者的判断是合乎实际情况的。 Mianyang, a branch of a company full-cycle aqueous solution of 150,000 t urea plant urea plant in the use of urea synthesis plant, respectively, in 2003 and 2005 overhaul of the tower in the open tower inspection, the bottom of the imported liquid ammonia in Superficial cracks were present on the inner surface of the pipe segment with a length of 150 mm welded to the spherical head, with depths of 2.0 mm and 1.0 mm, respectively, and lengths of 5 to 8 mm. The CO_2 and a liquid (ammonium carbamate) inlet pipe and weld but also found no cracks. Through the analysis that is under the conditions of production conditions caused by the long-term effects of temperature stress, this paper through the verification of stress calculations, confirms the author’s judgment is in line with the actual situation.