The box type structure, cavity cannot antirust paint corrosion, in order to prevent moisture intrusion corrosion beam cavity, sealing the inner cavity of the maingirder must keep.
箱型结构的主梁，内腔无法涂漆防锈蚀，为了防止水汽侵入腐蚀主梁内腔，必须保住主梁内腔的密封性。
2
The results show that the crane is unnecessary to replace for its low total stress level and large strength margin of the maingirder (main stressed part).
计算结果指出：门机结构总体应力水平较低，其严重受力件主梁具有较大的强度富裕度，不必更换。
3
To install the crane span before installation, camber, level of metal structure of maingirder bending, trolley rail height difference, gauge deviation, diagonal bridge survey.