Full-sized drilling tools are used for deivation prevention,the best placedment of the upper,middli and lower stabilizers is determined, et drilling is chosen to increase drilling rate,and the check valve type floating plug located at the tube end is employed to tackle tube lowering and grouting problems.

The boiler tripped and the fluid coupling parts was damaged because of an electric feed water pump non-return valve jam in Xuzhou Power Plant in early 2005.

The lab test of the performance of check valves which are used in the central exhaust system for residential kitchen is done, the results of the test is analyzed, and how the performance will affect the whole system, on its use and on its existence, is expounded.

Lab test was completed to determine the local resistance made by check valves used in exhaust system, it was concluded that local resistance coefficient of the electromagnetic valve tested will decrease with the valve open position largeror exhaust air rate increased.

Through numerical 3D simulation research for all plastic floating check valve with CFD software FLUENT,the pressure field and velocity field of the flow inside the valve were mastered while the valve was in working.