1, packing leak letter
This is a running, take, dripping, leaking main areas, in factories often seen.
Produced stuffing leaking because of the following points:
① filler and work of the corrosive medium, temperature, pressure, incompatible; ② filling wrong way, especially on the whole circle into the root filling, the most easy to produce leakage; ③ stem or surface finish machining accuracy is not enough, or have an oval degrees, or a notch; ④ stem pitting has occurred, or the lack of protection due to open rust; ⑤ stem bending; ⑥ filling materials used for too long, have become obsolete; ⑦ operating too fast.
Eliminating packing leakage is: ① the correct selection of filler; ② the proper conduct of filling; ③ stem processing failed, to repair or replace, the surface finish to achieve a minimum � 5, more important, to achieve � 8 above, and no other defects; ④ to take protective measures to prevent corrosion, has corroded to be replaced; ⑤ stem bending to straightening or update; ⑥ filling materials used by a certain time, to be replaced; ⑦ operator should pay attention to steady, slow to open slowly off, to prevent drastic changes in temperature or medium impact.
2, close the piece leak
Usually called the leak leak stuffing to close the piece is called in to vent. Off pieces of leakage, the valve inside, not easy to find.
Off pieces of leakage, can be divided into two categories: one is sealing surface leakage, the other is the root of leaking seals.
Caused by leakage of reasons: ① poorly sealing surface grinding; ② seal with the valve seat, valve flaps do not meet the stringent; ③ flap valve connected with the stem is not strong *; ④ stem bending and torsion, so that the upper and lower off pieces of misalignment ; ⑤ off too fast, bad, or had contact with sealing surface damage; ⑥ choice of materials properly, unable to withstand the corrosive medium; ⑦ will be cut-off valve, gate valve for regulating the use of. Sealing surface being unable to withstand the assault of high-speed flow of medium; ⑧ certain media, a gradual cooling in the valve closed, so that there slit sealing surface, there would be erosion phenomena; ⑨ some sealing surface and the valve seat, valve flap between the use of threaded connections, easy to produce oxygen concentration cell corrosion loose; ⑩ because of welding slag, rust, dust and other impurities embedded in, or production system has mechanical parts off block valve core, so that the valve could not close Yan.
Precautionary approach are:
① pressure test prior to use must be carefully leak testing and found that the root ring sealing surface spills or leaks, properly handle and then use; ② To check beforehand whether the various components of the valve intact, can not use the stem bending and torsion or valve flap and valve connection is not * the valve rod; ③ valve is crucial to stability strong, and not to Meng Jin, if found good contact between the sealing surface obstruct or block should be immediately opened a little bit, so that debris flow, and then carefully closed tightly; ④ selection valve, not only to consider the body's resistance to corrosion, but also to consider closing parts of the resistance to corrosion; ⑤ accordance with the structural characteristics of the valve, the proper use of the components necessary to readjust the flow control valve should be used; ⑥ for After the medium cooled off valve and a larger temperature difference between the situation, to cool and then look at the valve tightly closed; ⑦ seat, the valve flap and seal with screw connection, you can use Teflon tape for threaded between the filler, so there is no gap; ⑧ likely to fall into the impurities of the valve, the valve should be added before the filter.
3, stem lift failure
Stem lift failure reasons: ① operate too fast to thread damage; ② a lack of lubrication or lubricant failure; ③ stem bending and torsion; ④ surface finish is not enough; ⑤ tolerances allowed, gets the tight; ⑥ stem nut tilt; ⑦ improper choice of materials, such as the stem and stem nut for the same material, easy to bite; ⑧ thread is medium corrosion (refer to the dark bar at the bottom of the valve or the valve stem nut); ⑨ lack of protection for open-air valve , stem thread covered with dust and sand, or being corroded by frost and rain.
Prevention methods:
① meticulous operation, closed, not to Meng Jin, Do not turn to top dead center, open-hand wheel will be enough to reverse a couple of laps, so that screw on the side close together so as to avoid the impact of media to promote stem upward; ② regular checks of lubrication conditions, to maintain normal lubrication; ③ Do not use a long lever opening and closing valves, the workers used to a short lever to strictly control the force measured, to prevent torsional bending stem (referring to the hand wheel and stem directly connected to the valve); ④ increase processing or repair quality, and meet regulatory requirements; ⑤ corrosion-resistant materials to meet the working temperature and other working conditions; ⑥ stem and stem nut not to use the same material; ⑦ plastic to make stem nut, make checking intensity can not be only considered a good corrosion resistance and friction coefficient is small, must consider the intensity of the problem, the intensity is not enough, do not use; ⑧ open the valve stem to increase the protection cover; ⑨ normally open valve handwheel should be on a regular basis in order to avoid stem rust live.
4, other
Washer leak: The main reason is impatience corrosion is not suitable for working temperature and working pressure; there is high temperature valves. Prevention Methods: The working conditions compatible with the gasket on the new valve to check the suitability of gasket material, such as unsuitable to be replaced. For the high-temperature valve, to use it again another tight bolts.
Body cracking: General frozen making. Cold weather, the valve must be accompanied by thermal insulation measures, otherwise the valve should be halted and the connecting pipe clean water in the row (if any valve at the end of wire blocking, open wire blocking drainage).
Hand wheel damage: impact due to operation or long-lever vigorously. As long as operators and other relevant officers that could have been avoided.
Packing Gland Rupture: when pressed fill uneven force, or gland (usually cast iron) was flawed. Pressed fillers, to symmetrically rotating screws, non-skew. The time of manufacture not only pay attention to large and critical parts and pay attention to the Class of gland elements, or affect the use.
Stem and the valve plate connections failed: valve using stem rectangular head and the damper in the form of T-shaped slot to connect more, T-shaped slots are not always processed, thus allowing stem rectangular head wear faster. Mainly from manufacturing to resolve. However, units can also use the T-shaped slot to fill processing, it has a certain degree of finish.
Shuangzha pressure plate of the valve gate can not close the cover: Shuangzha plate tension is * generated by the top wedge, some valve, the top wedge material poor (low-grade cast iron), using the soon wear or break. The top wedge is a small pieces of materials used much, and use their own can be carbon steel production, replaced the original cast iron pieces. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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