- Valve packing chamber leakage with pressure plugging treatment
The use of injection pressure leakage plugging technology is currently a relatively safe and reliable means of technology, which uses a special fixture and hydraulic injection tool, the sealant will be injected into the fixture and the leakage part of the outer surface of the sealing cavity formed by the part of the cavity, and quickly make up for a variety of complex leakage defects. In the injection pressure is greater than the leakage medium pressure conditions, the leakage is forced to stop, injection itself in a short period of time by the plastic body into an elastomer, the formation of an elastic sealing structure and can maintain a certain sealing pressure, to achieve the purpose of re-sealing.
At present, domestic and foreign production and use of sealing agent is divided into two categories:
A class of heat-curing sealing agent, this kind of injection can only reach a certain temperature by the plastic body into an elastomer, at room temperature is solid;
Another category is non-heat curing sealing agent, it is suitable for room temperature, low temperature and high temperature occasions of dynamic sealing operation requirements, this kind of sealing agent is made into a stick solid or two-component putty material, will be loaded in the high-pressure injection gun, under a certain pressure with good injection process and filling, and does not lose the function of the valve switch.
- The following two commonly used methods:
1. for the valve stuffing box wall thickness greater than 8mm or so, in the dynamic conditions of the use of injection with pressure plugging to eliminate defects, can be directly in the valve stuffing box wall open injection holes in the way of operation, the sealing cavity is the valve's stuffing box itself, injected into the valve stuffing box within the sealing of the role of the injection and the role of the filler played the same. First of all in the appropriate position of the outer wall of the valve stuffing box with a diameter of 10.5mm or 8.7mm drill hole, the hole can not be drilled through, about to stay 1 - 3mm or so, withdraw the drill bit, tapping with M12 or M10 tap, tapping the end of the injection of special plug valves screwed on, and so that it is in the position of the open, with a diameter of 3mm of the long rod drill to the rest of the valve stuffing box wall drilling through, the leakage of media will be along the direction of the drill bit chipping away The leakage medium will be sprayed out along the direction of the drill bit chipping, in order to prevent high temperature, high pressure, toxic or corrosive medium sprayed out to prevent injuries when drilling, drilling small holes can be used before a baffle, first in the baffle on the drill bit to drill a diameter of 5mm holes so that it can be set over the long drill bit, coupled with the baffle drilling the rest of the wall thickness will not be a danger. Drill through the small hole after removing the drill, the injection of special plug valve screwed to the off position, cut off the medium connected to a high-pressure injection gun for the injection of sealing agent operation. If the pressure of the medium in the valve stuffing box is low, you can also use a long drill bit with a diameter of 3mm to drill through the hole directly and then carry out the sealing agent injection operation.
2. For valves with thin stuffing box walls, an auxiliary fixture can be used for dynamic sealing operations. The auxiliary fixture is only to make up for the lack of wall thickness of the valve stuffing box, equivalent to a special connector fixed in the outer wall of the valve stuffing box, used to connect the high-pressure injection gun. Fixture machining method is difficult to get the ideal local fit surface, under the conditions, you can properly repair the valve stuffing box wall, so that it is better fit with the auxiliary fixture. If the leakage valve packing wall shape is complex or repair conditions do not allow, can be in the bottom of the auxiliary fixture pad a piece of asbestos rubber sheet or rubber sheet, tighten the fixture bolts, so that the rubber sheet padded underneath can be well blocked fit surface gap. Auxiliary fixture should have a matching threaded patch with the injection plug valve, the next with the same wall thickness of the stuffing box operation in line with the entire sealing operation is completed, do not immediately switch the valve, and so on the sealing agent curing, before being put into normal use.
- Valve flange leakage with pressure plugging treatment
1. copper wire plugging method
It applies to the two flange gap is small, gap amount of uniformity, the leakage medium pressure is low with pressure plugging, can be removed in the bolt directly on the bolt special injection joints, generally not less than two. Installation of injection joints should be loosened a nut, install the injection joints, quickly re-tighten the nut, and then install another injection joints, not at the same time the required joints nut loosening, so as not to cause a significant decline in the sealing pressure on the gasket, leakage increased, and even leakage media will be blown away from the gasket, resulting in irreparable consequences. If the original leakage is large, available G-shaped clamp to maintain the balance of the sealing specific pressure, after the installation of the injection bolt, the tool will be the diameter or slightly smaller than the leakage of the flange gap of the copper wire embedded in the flange gap, and at the same time will be flanged out of the outer edge of the lip, so that the copper wire is fixed after the flange gap, which makes up the new sealing cavity. Then can be connected to the high-pressure injection gun for dynamic sealing operations, the injection direction should be from the opposite leakage point in turn, the end point should be in the vicinity of the leakage point.
2. Steel belt blocking method
When the gap between the two flanges is slightly larger and does not exceed 8mm, the medium pressure is less than 2.5MPa, can be used to steel belt plugging method for transport sealing operations. It has high requirements on the coaxiality of the two flanges, the flange gap uniformity requirements are not high. Steel belt generally choose 1.5 - 3.0mm thickness, width 20 - 30mm can be used, production can be used to weld or riveted, the two joints need to be added below the transition gasket, according to the flange size to determine the number of installed injection joints. When installing the steel belt, the steel belt should be located on the gap between the two flanges, the connecting bolts slightly screwed a few buckles, and then add the two transition gaskets, all wrapped around the flange gap, continue to tighten the bolts, and ultimately the formation of a complete sealing cavity, which can be dynamic sealing operations.
3. Flange convex fixture plug method
When the leakage flange gap is greater than 8mm, the medium pressure is greater than 2.5MPa, from the safety and reliability considerations, should be designed and produced into the processing of accurate dimensions, the overall sealing performance is good, high-pressure resistant flange fixture, which dynamic sealing operation of the success rate is higher, is a widely used sealing technology. Before the operation should be installed in a good fixture plug valve, and make the plug valve in the open state, the operator should stand in the upwind, if the leakage pressure or flow rate is very large, can be used to compressed air to the side of the leakage medium blowing, or in the fixture connected to a long rod, so that the operator to avoid and less contact with the leakage medium. When installing, the injection hole of the fixture should be in the middle of the two flange connecting bolts, and ensure that there is an injection hole near the leakage, do not make the injection hole aligned with the bolt, so as not to increase the resistance of the injection into. After the fixture bolts are tightened, the maximum gap between the fixture and the flange contact should not exceed 0.5mm, and the injector should be injected from the furthest away from the leakage point first, and then gradually close to the leakage until the leakage stops. The method can also be used for pipeline leakage plugging under pressure.
- Valve body leakage with pressure plugging treatment
Valve body leakage treatment can be applied to the pipeline leakage treatment, there are the following two methods.
1. Bonding method
It is a method of using the special properties of adhesives to plug leaks with pressure. For pressure media and leakage of small amount of sandhole parts, you can first polish the metal luster around the leakage point, and then use the taper pin aligned with the leakage point, the appropriate strength into the leakage, so that the leakage is significantly reduced or temporarily blocked. The use of adhesive curing speed characteristics, in a timely manner around the pin coated with adhesive, the establishment of a new solid sealing structure, to achieve the purpose of stopping the leak. For the medium pressure is high, the leakage of defects, available top pressure tools for sealing operations, the operation of the top pressure mechanism is fixed on the side of the valve, high-speed top pressure screw, so that the axial top pressure screw is facing the leakage point, rotate the top pressure screw, the use of top pressure screw end of the rivets pressed tightly on the leakage site, forcing the leakage to stop.
If the top of the rivet is smaller than the area of the leak, the rivet can be padded with a piece of soft metal under the leak stops, clean up the leak around the metal surface in a timely manner, remove rust and oil, will be prepared adhesive coated in the surrounding. To be fully cured adhesive, remove the top pressure screw and rivet fixing screws, remove the top pressure mechanism, in order to ensure its pressure-resistant effect, can be treated in the leakage site with glass cloth and other reinforcement.
2. Welding method
a) In the valve body of the leakage medium pressure is low, the leakage is small, can be used for an inner diameter than the leakage of more than twice the size of the nut, so that the leakage medium from the nut outflow, the nut welded to the valve body, and then with a bolt with the same specifications as the nut, in the bottom of the nut placed on the bottom of a piece of rubber or asbestos gasket, the top of the bolt wrapped around the tape screwed into the nut, to stop the leakage of the purpose. For leakage medium pressure is high, the leakage of large valve body, available diversion welding method. First of all, with a piece of iron plate, the middle of the opening of a round hole, and a round hole with a comparable caliber of the isolation valve welded to the round hole in the iron plate, open the isolation valve, the central hole of the iron plate aligned with the leakage point of the valve body, let the leakage medium through the central hole of the iron plate and the isolation valve outflow. If the fit surface is not good, you can place rubber or asbestos pads on the fit surface, and then weld the iron plate around the valve body, and then close the isolation valve will be able to achieve the purpose of re-sealing.
b) in the valve body of the leakage medium of high temperature and high pressure, but the valve has a large external dimensions, the leakage is not large, you can also use the welding method, first of all, directly to the valve body with the leakage related to the gap are welded (not welded leakage), and then with a section of the pipe to meet the conditions (operating temperature, pressure) of the length of the tube depending on the site environment (generally take about 200mm can be), its diameter should be greater than the leakage point, to a With the pipe to adapt to the valve welded to one end of the pipe, and fully open the valve, and then the other end of the pipe to take the leak aligned with the welded, close the valve to stop the leak.
- Universal plugging method
Regardless of which part of the valve leakage if the above methods of operation are difficult, you can also use the "parcel method": the use of plates (pipe) in line with the conditions of production of a valve can be wrapped up as a whole or there is a leakage of the valve body of the box, weld it to the valve so that it can be wrapped up leaks, if there are difficulties in the welding of the box, you can be on the box If it is difficult to weld the box, you can make a hole in the box and leave it until the end and then apply the method b) method in the method of welding: the method of adding the exhaust valve can be easily sealed and welded.