[Key words] gas station, valve fault detection, maintenance, use CLC number: TE974.3 Document code: A Article ID: 1009-914X (2017) 08-0039-01
Overview In the gas flow system, the valve is widely used as a workpiece, plays an important role in bearing on and off, the valve is the fluid line control device, whose basic function is to connect or cut off the flow of the pipeline medium to change the flow of medium, Regulate the pressure and flow of the medium, protect the normal operation of the pipeline and equipment. Therefore, to strengthen the valve station gas station management, rational use and maintenance, to prevent valve failure to maintain the valve good technical state, for the gas station to complete the normal gas transmission tasks to ensure the safety of the gas transmission and eventually Improve the economic efficiency of enterprises have a very important significance.
Gas distribution station mainly includes wedge gate valve, flat gate valve , globe valve , ball valve , throttle valve , safety valve and other types of valves, so how to eliminate the station run, run, drip, leakage phenomenon, and analysis to determine its The specific reasons that arise, and finally how to properly repair and maintain them is an important task in gas station management.
1. Existing valve routine maintenance and fault detection points 1.1 The routine maintenance of the valve Manual valve is the most widely used valve, its hand wheel or handle, is designed to be an ordinary manpower, taking into account the strength of the sealing surface and the necessary closure force. Therefore, you can not use the long lever or long hand to move plate. In the opening and closing the valve, the force should be smooth, not impact, for the Ming rod valve, to remember the full open and fully closed stem position, to avoid the full open impact on the dead point, if the spool seal embedded between the larger Debris, valve position when fully closed will have to change, so that the operator is promptly aware of the valve problems. Some media, after the valve is closed cooling, valve contraction, the operator should be closed again at an appropriate time, so that the sealing surface without fissure, or medium flow through the slit at high speed, it is easy erosion of the sealing surface . Operation, if found to be too strenuous operation, should analyze the reasons. If the packing is too tight, may be appropriate to relax, and some valves, in the closed state, the closure of the thermal expansion, resulting in difficult to open; if must be open at this time, the valve cap can be loosen half a turn to a circle, eliminating stem Stress, then pull the hand wheel.
1.2 valve fault detection and troubleshooting methods 1. In the gas station equipment management, accurately determine the valve fault location, causes, and timely troubleshooting, making it in good condition, is to prevent run, run, drip, leak the most effective measures . In my area over the years of maintenance experience, summed up many kinds of judgments on whether the valve leaks and maintenance methods, are summarized as follows:
1), method of operation: the use of opening and closing the valve, feel the flexibility of the valve operation to determine whether there is a problem valve.
2), the use of flow detection: When the upstream and downstream valve is closed, if the pipeline in the metering device is still running, said the valve there is leakage within the phenomenon.
3) The use of weather conditions for inspection: For example, the snow, the pipeline covered with a lot of snow, the temperature of the gas pipeline will be greater than the outside temperature, there is no snow above the pipeline. Conversely, snow covered pipelines, within There is no gas flow.
4), the use of pressure to detect whether the valve leak law, but the pipeline must have a pressure gauge, and with pressure conditions.
5), temperature method: the use of pipeline temperature to determine whether the valve leaks gas flow in the summer the pipeline temperature will be lower than the outside temperature, there will be pipelines water droplets generated.
2. Valve failure can be divided into external leakage, internal leakage, stem jamming, parts damage and other 4 ways.
1), external leakage valve leakage can be observed, wipe, oil and other visual methods to judge. Leakage of the valve packing, valve body, valve cover, flange four parts.
2), the internal leakage due to the valve infiltration, internal channeling with invisibility, the seriousness of its harm has not yet attracted enough attention. The harm is: a direct impact on the accuracy of measurement; if the valve infiltration, internal channeling caused by leakage, will provide a burning fire explosion.
3), stem jam When the valve hand wheel rotation, the valve stem driven by the rotation of the nut and make up and down movement, which led the gate movements, opening and closing the pipeline. Stem stuck phenomenon will lead to the valve can not work properly, so that it is not open, the lax.
4) Damage to parts Damage to parts is generally hand wheel damage, valve body flange damage, body freeze and so on.
2 The use of valve maintenance The purpose of the use of the valve is to extend the life of the valve and to ensure the reliability of opening and closing, valve running on the gas field station, run, drip, leakage phenomenon, the operator must first determine the cause of the leak , And then according to the actual situation of the corresponding maintenance, the following will be my area used by the valve repair technology is summarized as follows:
2.1 Valve screw rust In the gas station field due to some users of gas is continuous, and its long-term pipeline valve in the open state, due to the weather, resulting in the valve stem and packing gland at the rust , In order to make the valve switch flexible, rust rust Department rust, in order to prevent grinding screw rust caused by lead screw thinner and leakage, we require the site valve must be regularly maintained, for those who do not often move Valve, be sure to pay attention to the valve stem and packing gland full of butter, in order to achieve the purpose of anti-rust. The emergence of rust on the lead screw must use oil and derusting rust, never allow grinding valve screw.
2.2 seal valve gasket damage In the gas station, due to the valve life is longer, there are some valves are sealed with PTFE mat, and its older, there is leakage, the temporary can not find a suitable mat Replacement, there has been a seal gasket damage caused by the valve leaks, the need for its replacement cushions, squeezing the lid of the method, were not repaired, and later, from the sealant sealant sealant sealed, completely resolved The phenomenon of its leakage, from the maintenance so far, no leakage occurred, the effect is good.
2.3 Most of the leaky gas leakage valve seal through the packing, and some stations in the station as a result of failure to replace the packing, packing has led to the aging, dry, shrinking smaller, there has been leakage, At this time, it is necessary to unpack the packing gland, plus the oil will be soaking the packing for a period of time, and then hook it aside, replace the new suitable packing, pay attention to add packing, tighten the gland After the switch back and forth several times, so as to avoid too tight packing pressure, leaving the valve switch is not flexible. Sometimes there will be no aging packing, but the gland is still leaks, this time, may be appropriate to increase packing circle, squeeze the gland can be solved.
Valve packing in the uncompressed, flat on the case, there will be leakage phenomenon, most of this situation occurs in the operator less strength, the actual operation unskilled situation, therefore, when adding packing root, must To add a circle, pressure in a circle, each circle separated by 90 degrees, and the use of a screwdriver to be even formation, and then proceed to the next operation, you can solve this problem.
2.4 The valve between the valve body and the valve cover between the flange leak valve Flange seal is mainly relying on the bolt preload, through the gasket to achieve a sufficient seal than the pressure to prevent the leakage of sealed pressure fluid medium . There are many reasons for its leakage, gasket insufficient pressure, the surface roughness does not meet the requirements, gasket deformation and mechanical vibration, etc. will cause the seal gasket and the flange surface of the joint lax strict leak . In addition, deformation or elongation of the bolt, gasket aging, decreased resilience can also cause the flange surface sealing lax and strict.
2.5 valve sealing grease on the site all need to seal the valve sealing grease in accordance with the regular maintenance of equipment to add sealing grease, when sealing fat seal. Should be sealed grease gland unloading three buckle, the observation gland on the observation hole is not leaky before removing the gland, remove the seal valve core, into the seal fat sealing operation.
2.6 valve sealing surface damage or wear When the gas pipeline contains impurities, the valve sealing surface will inevitably be trapped in the transport process dirt, will be damaged in serious cases, then there will be valve leakage occurred in the valve completely closed After the air flow or pressure is still displayed, this time, the air can be used to rinse the debris, or the valve to open, specifically for the sealing surface cleaning, if conditions can be sealed surface re-grinding, if necessary, welding And processing, but grinding the sealing surface must be smooth, in order to achieve better sealing effect.
Conclusion Set in the production process, the valve plays an important role. Operating staff in the thought of enough attention, usually fine management, to take the proper maintenance methods. In order to extend its service life, is conducive to production and safe operation. In addition, the production station field equipped with emergency plugging tools and valve leak detection equipment, but also to ensure that all staff positions in the shortest possible time plugging a successful means; the same time to strengthen inspection, timely detection of failure, timely processing, Ensure station safety production.
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