Influence of stress-strain state on the reliability characteristics of the seals of pipeline valves
The ways of providing reliability characteristics of the seals of pipeline valves at a design stage are considered. The seal strength ratios are presented as well as ensuring conditions for piston sliding along the saddle. It is shown that ignoring this factor leads to the uncertain analysis of functional limitations and, therefore, it is necessary to choose the best combinations of the initial parameters. The equations are given to determine the width for the contact area and to determine the contact pressure on it. The stress component and the component of equivalent stresses in any point of the contact area are also given. The influence is shown for the friction coefficient on the value of equivalent stresses. It is shown that when the friction coefficient changes within the limits of μ = 0…0.3, the maximum equivalent stresses increase 1.7 times. The equations are obtained to determine the linear load q<sub>l</sub>, providing specified size of leakage. It is shown that after determining q<sub>l</sub>, it is necessary to verify static durability and bulk fatigue. It is also demonstrated that when the friction coefficient changes from 0.2 to 0.3, the size of bulk fatigue decreases by times.