Regulating valve site maintenance

1.valve-site maintenance

Valve due to the direct contact with the process medium, and its performance directly affects the quality and environmental pollution systems, so the valve must be regular maintenance and periodic maintenance, especially the use of harsh conditions and important occasions should pay attention to maintenance work.

Check Range Valves to adjust the focus of the maintenance of the site are:

1) The body wall. For use in high differential pressure and corrosive media occasions valve, body wall, diaphragm often subjected to shock and corrosive media, should focus on checking pressure, corrosion-resistant case.
2) seat. Fixed seat is a threaded inner surface susceptible to corrosion leaving the seat move, should focus on checking this site. To work under high pressure differential valve should also check whether the seat sealing surface is erosion, cavitation.
3) spool. Erosion by the media, the corrosion of the most serious overhaul to carefully check whether the valve parts are corrosion, wear, especially in the case of high-pressure differential, the spool due to cavitation wear more serious.
4) Check the diaphragm, "O" rings and other seals are cracked damage or aging.
5) packing. It should be noted PTFE packing, sealing lubricant is aging, whether mating surface is damaged, replace if necessary.
6) Annex inspection and maintenance to ensure the normal operation of accessories and other heater valves.

2.valve failure and sleep-site treatment

Common problems regulating valve is closed die, open, large hysteresis, leakage, vibration, oscillation, etc., for their handling are as follows:

1) spool off dead: The gas valve closed solution is to increase the air pressure or loosen the spring preload (ie reduce membrane outdoor starting pressure). Open the valve on the gas solution is to increase the spring preload. While increasing pressure steam source.
2) slow action or no action putt: inspection of the diaphragm, rolling diaphragm, gasket is aging, rupture, causing leaks.
3) Great Backlash: putter bent, whether packing gland pressure tight, especially graphite packing, or whether the valve guide surface injury. The solution is to change the stem, for packing, increasing the gap between the guide, for a strong executive body.
4) full stroke valve is not enough: the stem connector nut release. The spin valve stem outward or inward stretch, so the whole trip deviation does not exceed the allowable value and then the nut and tighten.
5) Valve small opening poor stability: Live First check whether the flow is installed backwards, or valves election is too large, the solution according to the installation flow, reduce the spool size.
6) leakage volume: First check whether the sealing surface damage, seat number connecting thread is loose, the pressure valve is closed when the output power is greater than the actuator. The solution is to replace the sealing surface, and tighten the seat, replacing the high output power actuator.
7) Vibration sharply: the probability of the selected frequency and the frequency of the valve system is the same, the vibration will change drastically, this phenomenon was about 1% when the. The solution is to switch to a different structure of the valve.
8) Oscillation phenomenon: is due to the valve is small opening or closed due to the flow of the stream. The solution is to avoid the small opening, changing, open-type work.