A mathematical model about the duration of seal test of hydrostatic test for gas pipeline was developed firstly.

The entry-exit inspection stations throughout the country should raise the awareness of the officers and soldiers, strengthen and enhance the organizations, so as to meet the requirement of more affinity service and more close administration and control.

Measures to improve the tightness of air-duct made of galvanized sheet;

ACC tightness is one of the key targets to examine the power plant unit,it directly influences the units of economic operation.

The influence of vacuum system tightness of 200 MW unit on the unit operation is discussed.

The condition equations?normal equations?precision evaluation of rigorous adjustment methods with two shafts orientation and Gyro orientation jointing application have been discussed with a case studies for the feasibility and precision promotion.

The paper introduces a method of horizontal control survey of tunnel s exterior by adopting polygon closed traverse loop, assumed independent coordinate system , rigorous adjustment , adopting approximation to estimate the lateral error of tunnel and the calculation of precise kilometer and curve turn angles,thus the throughout accuracy of the tunnel was improved.

Study On The Factors That Affect The Tight Degree of Pulverous Needle Agents;

Characteristics of the rotary valve with adjustable range,tight shutoff,more capacity,resisting cavitation etc.