What are the common leakage parts of high pressure valves?
Valve common leakage parts are mainly in the flange and stem sealing discs and other parts with seals, these parts of the leakage is often due to damage to the seals or fastening bolts caused by loosening.
1.Valve body flange leakage
Valves, especially large diameter high-pressure valves are generally more than 2 parts assembled through the parts of the flange, these parts flange is generally not a standard flange, not only round and oval. These flanges in the valve factory has been fully tightened by the production plant and test pressure, due to the connection of the valve flange fastening is tightened up without the influence of external stress, so in the long-term production and use of leakage is not easy to produce or there will be a slight leakage through the bolts can be prevented from expanding the leakage again, so it generally does not affect the smooth operation of production.
2. Valve connection flange leakage
Valve connection flange leakage is the leakage of the flange between the valve and the connected pipeline, flange connection is the most commonly used connection between the valve and the pipeline, more convenient than the welded and clamped connection, replacement of the valve is also more simple. Connection flange is generally a standard flange, when the valve is put into use with the pipeline connection, due to the valve connection flange and pipeline flange in the tightening of the bolt when there is a part of the pipeline stress, restricting the pipeline flange and the valve connection flange sealing, so even if the bolts are sufficiently tightened will inevitably produce leakage, especially the pipeline flange between the replacement of the valve connection, the flange leakage between the flanges is more common.
3. Valve stem seal packing leakage
Valve packing is a sealing material used in the valve, by the softer thread woven into, and then filled with graphite or other fillers, through the cross-sectional area is a square strip, used for valve stem parts of the seal, the valve sealing packing styles and types of many, in the valve manufacturer to assemble the valve in the valve assembly process packing is generally shaped flexible graphite, as long as from the upper end of the valve stem one by one into the set, and then carefully set into the stuffing box, and then carefully set into the packing box, and then carefully set into the packing box, and then carefully set into the packing box, and then carefully set into the packing box, and then carefully set into the packing box. Then carefully set into the stuffing box, symmetrically tighten the gland stud can be. Packing leakage exists in the valve after a long period of switching, mainly due to the medium transported within the valve on the packing corrosion and stem in the movement of the packing wear and tear, packing the slight leakage can generally be dealt with by tightening the packing gland bolts, but there are due to the tightening of the gland to the end or packing corrosion caused by the serious splintering of the material, which requires other ways of dealing with.
- Valve leakage with pressure treatment
Valve leakage to replace the valve or replace the leakage part of the seal is of course the most direct way, but these methods must be disassembled or the valve will be conveyed in the process of the media can be emptied, so there are great limitations, especially in the petrochemical production process if a valve leakage due to stopping to deal with the impracticality of this will cause a very negative impact on the production of the company will also cause great economic losses. This will cause a very negative impact on production and will also cause huge economic losses to the company, so after the valve leakage pressure plugging has become a more effective way to deal with the leakage faults of a more effective way to minimise the losses caused by the production of the processing methods.
Leakage plugging with pressure refers to the pipeline and the valve conveying medium is not emptied, the production process does not stop, in the case of conveying the medium continues to leak parts of the material under the circumstances of the sealing of the treatment method. Now pressure leakage plugging technology is widely used in electric power, chemical industry enterprises, become an important means of achieving long cycle, no leakage operation, but also to avoid parking material discharge, not only to the enterprise to bring considerable economic benefits, but also has great environmental significance.
There are many ways to plug leaks with pressure, according to different processing methods such as support method, top pressure method, clamp method, gland method, packing method, upper cover method and expansion method. According to the site conditions and processing capacity, can also be a reasonable combination of the above two or more plugging methods, but in the valve leakage with pressure treatment is commonly used in the following two treatment methods.
① Leak plugging method with fixture is mainly used for the leakage of valve flange, the leakage of connecting flange of valve and pipeline is simpler to deal with with fixture, because these connecting flanges are round and belong to the standard parts, so the manufacture and installation of fixture is relatively simple, and the leakage of body flange of the valve is not a regular round flange and it does not belong to the standard parts, so it is more complicated to make the fixture.
In the pressure plugging technology, fixture design and manufacture of good and bad has a very important role, the fixture is not used to directly plug the leak, but to play an auxiliary role, the fixture tightly clamped in the leakage of the flange on the outside of the fixture, the fixture's curvature and the flange arc coincides with, and then through the special injection tool, the special pressure plugging sealant injected into the fixture and the flange in the flange parts and fixture between the formation of dense Then the special pressure sealant is injected into the fixture and the flange by the special injection tool, forming a dense filling between the flange part and the fixture and forming a new seal, thus playing the role of sealing the leakage point.
② Valve body perforation injection method Valve body perforation injection method is mainly applicable to the valve packing due to severe wear or corrosion caused by the leakage treatment.
Before the valve body glue injection, first in the valve wall of the stuffing box to open the glue injection hole operation, due to the glue injection hole to withstand greater pressure and also in the hole tapping threads, so it is best to open a hole in the outer wall of the stuffing box to measure the thickness, while checking the site whether there are other defects; to determine a good hole location with a hand drill and 10mm or so of the drill hole, the hole should not be a one-time drilling through to leave a 1 ~ 2mm wall thickness, in order to prevent the medium conveyed within the valve spray injury to the follow-up work unnecessary. In order to prevent the medium conveyed within the valve to prevent injuries caused by spraying, causing unnecessary trouble to the follow-up work, the injection hole open and tapping threads and then install the injection of special plug valve spool, can also be welded to the plug valve spool injection holes, as shown in the figure below. After that, then use a long drill bit to inject the remaining 1 ~ 2mm wall thickness of the hole drilled through, then the medium transported within the valve will be tapped along the drilling direction outward spray, at this time the plug valve spool is placed in the position of the off position, you can stop the medium within the valve along the plug valve spool sprayed out at the same time connected to the injection of the gun, to the leakage of the stuffing box continuous injection of glue until the leakage of the stuffing box no longer leaks outward that is, to stop injecting glue, and at the same time tighten the plug valve. At the same time, tighten the plug valve spool to complete the stuffing box with pressure plugging.