Maintenance and Repair During Valve Operation
May 17, 2023
Maintenance during valve operation
During the running of a pipeline system, the pipeline should be kept clean, the passage unobstructed, the various parts well lubricated, and the valve accessories complete. Maintenance is the key to the normal operation state.
Keep the valves on the pipeline clean and the paint of the valves intact. Frequently blow them with compressed air to prevent dust and dirt on the surface of the valves. Check 1 or 2 times per shift. Regularly open the flushing valve and the plug at the bottom of the valve to clean the dirt at the bottom of the valve. The lubricating parts of the moving parts of the valve should be lubricated frequently. For high-temperature valves, molybdenum disulfide or graphite powder should be added once a week for one month. Engine oil and grease should not be added. For valves that are not opened frequently, the lubrication cycle can be in accordance with the internal regulations of the company. For those that should be greased, grease should be injected regularly, otherwise, it is easy to wear and leak. Keep all kinds of parts of the valve complete. The loose flange nuts caused by pressure fluctuations and temperature fluctuations should be tightened in time, and the nuts on the packing gland bolts and handwheels should also be tightened in time if they are loose. Long-term non-tightening will cause leakages of flange and affect the matching accuracy, resulting in improper opening and closing.
The static seal of the packing as the valve stem is relatively easy to wear and causes leakage due to the frequent opening and closing of the valve, which is a common problem in the pipeline system. Generally, it is solved by adding packing. When you add packing, it should be prepared in advance. If suitable packing is used, loosen the packing gland and add the packing immediately, and then tighten the gland nut. If it is a high temperature, ultra-high pressure, or highly toxic medium, corresponding protective measures should be taken.
All kinds of driving devices matching with valves should be maintained carefully, at least once a month. The appearance should be clean; the device should not be contaminated by steam, water and oil. The electrical cabinet, hydraulic pressure and pressure joints should be complete and in good condition, and the indicator lights should be correct. Keep the driving device in good working condition to meet requirements for valve opening and closing.
Repair of valves
Valve maintenance is an effective way to extend the service life of valves. It is divided into online maintenance and offline maintenance. On-line maintenance is further divided into shutdown or non-pressurized maintenance and pressurized maintenance.
Shutdown maintenance (without pressure means that there is a cut-off valve in the upstream of the pipeline to cut off the pressure) involves two kinds. One is that the sealing pair is invalid, and it cannot be closed well, such as a top entry ball valve. The other is that the valve cannot be opened or closed suddenly. It is probable that other parts such as wedges and valve stems are damaged except the sealing pair. If there are parts, the valve can be repaired in a short time. Because the valve has not been tested separately, it is necessary to carefully observe the working status of the valve when starting up. Take timely measures.
Pressurized maintenance
is a relatively dangerous job. It is necessary to formulate a maintenance plan, including notifying the original supplier and taking safety measures. If the medium is harmful or poisonous, protection work should be done well. If welding is to be done, fire prevention measures should be taken. In short, maintenance under pressure is very arduous and should be highly valued.
Off-line maintenance is also called valve removal maintenance (maintenance after valve replacement). A valve can be repaired by the company, returned to the supply unit or entrusted to other qualified valve maintenance units.
During the running of a pipeline system, the pipeline should be kept clean, the passage unobstructed, the various parts well lubricated, and the valve accessories complete. Maintenance is the key to the normal operation state.
Keep the valves on the pipeline clean and the paint of the valves intact. Frequently blow them with compressed air to prevent dust and dirt on the surface of the valves. Check 1 or 2 times per shift. Regularly open the flushing valve and the plug at the bottom of the valve to clean the dirt at the bottom of the valve. The lubricating parts of the moving parts of the valve should be lubricated frequently. For high-temperature valves, molybdenum disulfide or graphite powder should be added once a week for one month. Engine oil and grease should not be added. For valves that are not opened frequently, the lubrication cycle can be in accordance with the internal regulations of the company. For those that should be greased, grease should be injected regularly, otherwise, it is easy to wear and leak. Keep all kinds of parts of the valve complete. The loose flange nuts caused by pressure fluctuations and temperature fluctuations should be tightened in time, and the nuts on the packing gland bolts and handwheels should also be tightened in time if they are loose. Long-term non-tightening will cause leakages of flange and affect the matching accuracy, resulting in improper opening and closing.
The static seal of the packing as the valve stem is relatively easy to wear and causes leakage due to the frequent opening and closing of the valve, which is a common problem in the pipeline system. Generally, it is solved by adding packing. When you add packing, it should be prepared in advance. If suitable packing is used, loosen the packing gland and add the packing immediately, and then tighten the gland nut. If it is a high temperature, ultra-high pressure, or highly toxic medium, corresponding protective measures should be taken.
All kinds of driving devices matching with valves should be maintained carefully, at least once a month. The appearance should be clean; the device should not be contaminated by steam, water and oil. The electrical cabinet, hydraulic pressure and pressure joints should be complete and in good condition, and the indicator lights should be correct. Keep the driving device in good working condition to meet requirements for valve opening and closing.
Repair of valves
Valve maintenance is an effective way to extend the service life of valves. It is divided into online maintenance and offline maintenance. On-line maintenance is further divided into shutdown or non-pressurized maintenance and pressurized maintenance.
Shutdown maintenance (without pressure means that there is a cut-off valve in the upstream of the pipeline to cut off the pressure) involves two kinds. One is that the sealing pair is invalid, and it cannot be closed well, such as a top entry ball valve. The other is that the valve cannot be opened or closed suddenly. It is probable that other parts such as wedges and valve stems are damaged except the sealing pair. If there are parts, the valve can be repaired in a short time. Because the valve has not been tested separately, it is necessary to carefully observe the working status of the valve when starting up. Take timely measures.
Pressurized maintenance
is a relatively dangerous job. It is necessary to formulate a maintenance plan, including notifying the original supplier and taking safety measures. If the medium is harmful or poisonous, protection work should be done well. If welding is to be done, fire prevention measures should be taken. In short, maintenance under pressure is very arduous and should be highly valued.
Off-line maintenance is also called valve removal maintenance (maintenance after valve replacement). A valve can be repaired by the company, returned to the supply unit or entrusted to other qualified valve maintenance units.
