Base on the stress strain relationship and principle of co deformation,this paper from theory analyses the relative compression height of strengthened beam with steel plate,and presents the concept of boundary fracture.

Relations between ductility of the reinforced concrete shear wall and its relative depth of compressive zone of concrete section (or ratio of compressive stress to compressive strength of concrete), confinement of boundary zones, and aspect ratio were studied.

Regarding the damage and leakage of drying gas sealing of multi-stage centrifugal HP ammonia pump, The reason is analyzed as follows: failure of a mechanical seal part pushing ring shaft sleeve inside mechanical seal and fixed shaft sleeve to move outside;increased specific pressure of movable ring and fixed ring;aggravated tear and wear of seal surface, resulting in damage and leakage.

Ltd of Italy adopted for the first time the mediate rate centrifugual HP ammonia pump produced by NP Ltd.