High pressure butterfly valve leakage is a more common problem, but in some important systems and equipment, high pressure butterfly valve leakage will affect industrial production and serious some will also endanger the safety of people's lives and property. The high and middle pressure butterfly valve is connected with the main and auxiliary equipment and system of the power station, and its importance is self-evident. The following analysis of several power station high pressure butterfly valve leakage treatment methods:

First, high pressure butterfly valve packing leakage

The stem and packing will form a state of motion between each other, which will be reflected in the use of high pressure butterfly valves. The more times you press the butterfly valve, the more movement you will have. Coupled with the role of temperature, pressure, etc., will greatly increase the possibility of high and high pressure butterfly valve packing leakage, during this period of time, the pressure of the packing will gradually reduce, thus aging, elasticity no longer exists. The pressure medium will leak outwards from the contact gap between the filler and the valve stem. If this problem is not properly solved, over time, the problem of blowing away the seasoning and leaving the valve stem from the groove will be formed, making the leakage surface bigger and bigger.

2. Flange leakage

The causes of flange leakage are often more than one aspect, such as the sealing gasket compression force is not enough, the roughness of the combined surface is a certain distance from the requirements, the gasket deformation, etc., resulting in the sealing gasket and the flange are not fully in contact with each other, and the leak is generated. At the same time, the causes of the flange surface seal are also deformation or elongation of bolts, aging of gaskets, reduced resilience, cracking, etc., which can also produce leaks. In addition, human factors are also aspects of flange leakage that need special attention. In addition, the valve body will also produce the problem of leakage due to the limitation of space, here do not go into details.

Third, the method of dealing with the external leakage of the high pressure butterfly valve of the power station

Packing chamber leakage treatment with pressure plugging

There are many ways to deal with the external leakage of high and middle pressure butterfly valve in power station, among which the more safe is the injection type with pressure plugging technology, which has been more detailed conclusions. This method uses a special fixture and a hydraulic injection tool to inject the sealant into the sealing cavity formed by the fixture and the outer surface of the leak site, and the effect of remediating the leak defect is better and the time is shorter. When the pressure of the injection exceeds the pressure of the leaking medium, it will strongly stop the leak, so that the injection is transformed from a plastic body to an elastomer, at this time the sealing structure has a certain elasticity, and there is a certain specific pressure of the working seal, the secondary seal is eventually formed, which undoubtedly increases the good sealing. Today in China, the application and promotion of sealing injection is more of the following two types: (1) heat curing sealing injection. The use of this injection needs to meet certain conditions, that is, temperature, temperature reaches a certain degree of the case, the injection is an elastomer, generally solid. (2) non-heat curing seal injection. Its range of application is very wide, can be operated under various temperature conditions, high pressure injection gun can also be installed, injection and filling are better, high pressure butterfly valve switch function can also be well preserved. When the wall thickness of the stuffing box of the high and middle pressure butterfly valve is more than 8 mm, the injection hole can be set directly on the wall of the stuffing box of the high and middle pressure butterfly valve. The sealing cavity is the stuffing box of the high and middle pressure butterfly valve itself, and the sealing injection can play the same role as the stuffing. Find a suitable location in the outer wall of the high pressure butterfly valve stuffing box with a diameter of 10.5 mm or 8.7 mm drill, it should be emphasized here that this hole should not be drilled through, the distance should be between 1-3 mm, the drill bit out, with M12 or MIO tap tap, when this work is completed, and then tighten the special plug valve for injection. The valve should be in the open state, and then choose a long rod drill bit, which should be selected with a diameter of 3 mm, in order to drill through the remaining high pressure butterfly valve stuffing wall, and the leakage will be emitted with the direction of the drill bit. Drilling will have a certain risk, mainly because the temperature or pressure is too large or contain toxic substances will bring a certain amount of damage to the staff, light injury, heavy will also threaten the safety of life, so this absolutely can not be ignored, before drilling baffle is a better control method.

Flange leakage with pressure plugging treatment copper wire containment method

The scope of application of this method is that the gap between the two flanges is small, the gap amount is uniform, the leakage medium pressure is low with pressure plugging, and the special injection joint of the bolt is placed on the removed bolt, and the two are lower and should be greater than two. When installing the injection joint, do not tighten all the nuts, but loosen one. After installing the injection joint, tighten the nuts immediately and install other injection joints. It should be emphasized that the required joint nuts cannot be loosened at the same time, because it will reduce the specific seal pressure on the gasket, increase the leakage amount, and in serious cases, the leaking material will blow away the gasket. If this happens, it is difficult to remedy and the damage is incalculable.

Valve body leakage with pressure plugging treatment

1. Bonding method

If it is the pressure medium and the trachoma part with a small amount of leakage, the metal luster can be polished around the leak point first, and then the taper pin is aligned with the leak point to drive in with appropriate strength, mainly in order to reduce the leakage or temporary plugging. The adhesive curing speed is relatively fast, and this feature can be used to coat the adhesive around the pin, so as to form a new solid seal structure, which can produce a leak-stopping effect to a certain extent. If the medium pressure is high and the leakage is large, the sealing operation can be carried out, the way of the top pressure tool is used, the top pressure mechanism is fixed on the side of the high school pressure butterfly valve during the operation, the high-speed item pressure screw, so that the axial direction of the top pressure screw is opposite the leak point, the rotating item pressure screw, and the rivet at the end of the top pressure screw is tightly pressed on the leak site, which is also an effective way to stop the leak. If the top of the rivet is less than the area of the leak point, a soft metal sheet can be padded under the rivet. When the leakage stops, the metal surface around the leak point should be cleaned in time.

2. Welding method

If the leakage medium pressure of the valve body is low, the leakage amount is small, the inner diameter of the nut can be more than twice the leak point, so that the leakage medium can flow out from the nut, the nut is welded on the valve body, and then with a bolt of the same specification as the nut, a rubber pad or asbestos pad is placed at the bottom of the nut, and the top of the bolt is twisted into the nut with raw tape. It can effectively reduce the occurrence of leakage. If the leakage medium pressure of the valve body is high and the leakage amount is large, then the drainage welding method is a better method. First use a piece of iron plate, open a round hole in the middle, weld an isolation valve with a diameter equivalent to the round hole on the iron plate, open the isolation valve, align the center hole of the iron plate with the leak point and fit in the valve body, so that the leakage medium flows out through the center hole of the iron plate and the isolation valve. For the case that the fitting surface is not good, the rubber or asbestos pad can be placed on the fitting surface, and then the iron plate is welded around the valve body, and then the isolation valve is closed, so that the sealing effect can be achieved.