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

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.