1, stuffing box leakage This is the main run, run, drip, leak, often seen in the factory. Leakage caused by the stuffing box has the following reasons: ① filler and the working medium corrosive, temperature and pressure do not match; ② filling method is wrong, especially the whole packing into the spiral, the most prone to leakage; ③ stem processing Precision or surface finish is not enough, or oval or scored; ④ stem pitting has occurred, or due to lack of protection of the open rust; ⑤ stem bending; ⑥ filler used too long, has been aging; ⑦ operation too fierce. The method to eliminate the packing leakage is: ① the correct choice of packing; ② according to the correct filling; ③ valve processing unqualified, to repair or replacement, the minimum surface finish to achieve? 5, more important, to achieve? 8 above, And no other defects; ④ take protective measures to prevent corrosion, corrosion has to be replaced; ⑤ stem bending to be straightened or updated; ⑥ filler to use a certain time, to be replaced; ⑦ operation should pay attention to smooth, Prevent drastic temperature changes or media shocks. 2, the closure of the leak is usually leaked stuffing box called leakage, the closure is called internal leakage. Leakage closure, inside the valve, not easy to find. Closure pieces can be divided into two categories: one is the sealing surface leakage, and the other is the root seal leakage. Leakage caused by the reasons are: ① sealing surface grinding is not good; ② seal ring and the valve seat, the valve is not tight with the valve; ③ valve and valve stem connection is not strong *; ④ stem bent, so that the upper and lower closure is not aligned ; ⑤ close too fast, poor contact surface seal or has long been damaged; ⑥ improper choice of materials, can not withstand the corrosion of the medium; ⑦ the valve, gate valve for the control valve. The sealing surface can not withstand the erosion of high-speed flow medium; ⑧ some media, the valve is closed and gradually cooled, so that the sealing surface slippage, will also have erosion; ⑨ some sealing surface and valve seat, Between the use of threaded connections, prone to oxygen concentration of the battery, corrosion loose; ⑩ due to welding slag, rust, dust and other impurities embedded, or mechanical parts in the production system off the plug block valve so that the valve can not be closed. Preventive measures are: ① must be carefully pressure test leaks before use and found that the leak sealing surface or the root seal leaks, to be handled properly before use; ② To check the valve components are intact, can not use the valve stem bending or valve flap And the valve stem can not * * valve; ③ valve is closed to make steady, do not make Meng Jin, such as the seal surface is not good or there is a barrier between the open, should immediately open a little, so that debris outflow, and then carefully closed; ④ When using the valve, not only to consider the corrosion resistance of the valve body, but also to consider the corrosion resistance of the closure; ⑤ in accordance with the structural characteristics of the valve, the proper use of components that need to adjust the flow control valve should be used; ⑥ valve After the medium is cooled and the temperature difference is larger, the valve should be tightly closed after cooling. ⑦ When the valve seat, the valve disc and the sealing ring are screwed, PTFE tape can be used to fill the thread between the threads so as not to have Space; ⑧ may fall into the valve impurities, valves should be added in front of the filter. 3, stem lift failure stem lift failure due to: ① excessive operation of the thread damage; ② lack of lubrication or lubricant failure; ③ stem bending and torsion; ④ surface finish is not enough; ⑤ with the tolerances are not allowed to bite too Tight; ⑥ stem nut tilt; ⑦ improper choice of materials, such as stem and stem nut of the same material, easy to bite; ⑧ thread corrosion by the medium (refer to the dark rod valve or stem nut in the lower valve); ⑨ open Valve lack of protection, stem thread covered with dust, or by the rain and snow rust. Precautionary approach: ① careful operation, do not turn off when Meng, open Do not go to the top dead center, open the hand after the turn one or two laps, the thread close to the top, so as to avoid the media to promote upward impact on the valve stem; ② often Check the lubrication conditions, to maintain normal lubrication; ③ Do not use the long lever to open and close the valve, accustomed to using short-lever workers to strictly control the force propriety, to prevent the torsion stem (refer to handwheel and stem directly connected to the valve); ④ improve the quality of processing or repair, to meet the specifications; ⑤ material corrosion-resistant, to adapt to the working temperature and other working conditions; ⑥ stem nut do not use the same material with the stem; ⑦ plastic stem nut, to check the strength , Can not only consider the corrosion resistance is good and the friction coefficient is small, must also consider the strength of the problem, the strength is not enough, do not use; ⑧ open valve to add stem protection sleeve; ⑨ often open the valve, to regularly rotate the hand wheel, live. 4, other gaskets leaks: The main reason is not resistant to corrosion, does not adapt to the working temperature and working pressure; There are temperature changes in high temperature valves. Prevention: The use of working conditions with the gasket, the new valve to check the gasket material is suitable, if not suitable, it should be replaced. For high-temperature valve, to use again when the bolt again. Body cracking: caused by the general freezing. When the weather is cold, the valve should be insulated with heat measures, or after the shutdown should drain the valve and the connecting pipe clean (if there is a plug at the end of the valve, you can open the plugging drainage). Damage to the handwheel: Crash or long lever caused by violent operation. As long as the operator and other relevant personnel pay attention, can be avoided. Packing gland fracture: Uneven packing force, or gland (usually cast iron) is defective. Compacted packing, to be symmetrical to rotate the screw, not skewed. Manufacture should not only pay attention to large and key parts, but also pay attention to gland and other minor parts, otherwise affect the use. Stem and valve plate connection failure: The valve stem rectangular head and gate T-slot connection in the form of more, T-slot sometimes not processed, so the stem square head wear faster. Mainly from the manufacturing side to solve. But the use of units can also T-slot for additional work, it has a certain finish. Double gate valve gate can not compress the sealing surface: double gate tension is generated by the * wedge, some gate valve, wedge material is not good (low grade cast iron), worn or broken soon after use. Top wedge is a small piece of material used by small, the use of units can be made of carbon steel, replace the original cast iron pieces.

NOZZLES AND CLEANING HEADS

NOZZLES AND CLEANING HEADS

NOZZLES AND CLEANING HEADS

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