Φ1200氨冷器壳体裂纹原因分析及对策

Countermeasure and analysis of reasons for refrigerating container with ammonial flaw Φ1200

以某化肥公司Φ1200氨冷器壳体开裂泄漏的失效分析为例,通过对检验数据和结果及有关文献资料的分析研究,探究了液氨介质压力容器产生应力腐蚀裂纹的原因:①设备中存在较高的焊接残余应力;②液氨介质具备应力腐蚀环境,即含水量≤0.2%,且有空气(O2或CO2)污染(或掺入),使用温度高于零下5℃;③母材强度越高,应力腐蚀裂纹产生的倾向就越大.针对上述原因提出了防止氨冷器类临氨压力容器产生应力腐蚀裂纹的对策:①选用强度稍低,但抗裂性较好的低碳钢和低合金钢,如用20R钢制造;②焊接时应采用严格的工艺措施和较低的焊接热输入量;③焊后应及时进行整体消除应力热处理;④控制焊接接头各区硬度HB≤185;⑤在液氨中添加0.25%的水作为缓蚀剂;⑥在运行中加强检查,及时进行停车检修时的内外部检查和定期检验.

The paper mainly discussed the reasons of stress from liquid ammonia pressure vessel causing crack through examing data and experimental results and analysing relevant referential documents and materials, taking Φ1200 ammonia v essel's crack and leaking in a certain fertilization company as an example:①the re existed remaining welding, stress in the equipment; ②there existed a stress decaying surrounding, i.e., moisture≤0.2%, and temperature >-5 ℃with O2 or C O2 inside; ③the higher the intensity of raw materials, more possible it was to have stress decaying crack. According to these, the paper put forward some count ermeasures:①select low carbon steel or low metal alloy steel with lower intensi ty, like 20R steel; ②while welding, adopt strict craft measures with lower weld ing heat to input; ③after jointing, proceed the whole hot dissolving on time; ④control each welding joint with hardness HB≤185; ⑤add 0.25%water into the l iquid ammonia as decay eclipse; ⑥enhance checking in operation, repairing equip ment in time through regular interior and exterior checking.