In order to achieve zero leakage sealing ball valve inside and outside, to save energy, protect the environment and improve work efficiency, valve must have a reliable sealing performance, ball valve sealing performance is the ball valve part of the sealing ability to prevent media leaks, it is under test conditions rated valve internal and external leaks. Contact points with the department, filler stem and the stuffing of the main parts of the opening and closing ball valve sealing member and the ball valve seat sealing surface between the body and bonnet connection which is called before a leak within the leak, also is commonly known as a bad relationship, it will affect the ability of the ball valve cut off media, for the cut-off valve, the internal leakage is not allowed, Leakage after the two called the leak, that media leaks from the valve to the valve outside , Leakage will result in material losses, environmental pollution can also cause serious accidents. The sealing performance of the valve is an important indicator of valve function and quality.
The ball valve leakage problem a serious threat to the normal operation of the device, and the operation of the ball valve and very difficult to find whether there is leakage, the survey results show that the use of a variety of petrochemical enterprises each with varying degrees of valve leakage problems exist, the reason there is a ball valve plate, seat sealing surface material does not meet the requirements, processing accuracy is not enough, gate valve plate, seat wedge angle does not match, the sealing surface varies in width, fit is poor, the shutter is not in place, and other factors related death. Such as: For flange cast steel gate valve, the sealing surface material code should refer to the hardness of sealing a relatively soft sealing surface material, other seal face materials shall be at least apparently corresponding carbide, and in fact there are only one valve sealing surface surfacing hard alloy and the other sealing surface of the bulk material is carbon steel, and put into use not long to occur due to wear and tear in the drain phenomenon. Another example of a piping system selected folder-off valve, seat material PTFE, the use conditions, the demand is not high, it is normal temperature and pressure, but found a large number of in trial run The ball valve closed lax, leakage severe that they cannot normally use, and finally had to replace a valve, removed examination found that the closed state of the ball valve plate and seat a great gap, even light. Analysis of the reasons may include the following: the structural design manufacture and assembly of precision unreasonable or ball valve seal pair fail to meet requirements; failure to require the construction and installation of the ball valve so that it put too much force; the construction process in welding slag, sand, metal shavings and other debris from entering the ball valve chamber, the sealing effect is affected. In fact, more practical, it is the most fundamental reason is that in the valve manufacture, transportation or installation process fails certain standard requirements to do so.
The explosive, toxic or radioactive medium, leakage is allowed, and therefore, the ball valve must have a reliable sealing performance.