The valve sealing requirements

Valve sealing performance refers to the sealing parts of valve's ability to prevent leakage of medium, it is the most important technical performance index of the valve.There are three sealing parts of the valve : open-close part and seat the contact point between the two sealing surface;Packing cooperate with stem and packing gland;The joint of the body and bonnet.One former place called internal leakage of leakage, known as the closed lax, it will affect the valve truncation medium capacity.For block valves class, the internal leakage is not allowed.After the two called the outside leakage, the medium from leaking to the outside of the valve from the valve.Leakage would cause material loss, environmental pollution, serious when still can cause accidents.For flammable and explosive, toxic or radioactive medium, leakage is not allowed, so the valve must have a reliable sealing performance.

（source：http://www.kg-machinery.com/news/the-valve-sealing-requirements.html）