Operation and Management of Valves in Urban Water Supply Network

Background
 
The pipeline management office of Nanjing Water Group Co., Ltd. is mainly responsible for the maintenance of more than 5,000 kilometers of water supply pipelines and more than 90,000 water supply facilities, including more than 80,000 water supply valves. Due to the reasons of maintenance, new construction of pipelines, adjustment of water supply area, etc., it is common to stop and restore water in local water supply pipelines, and the regular operation of water supply valves is the key to the successful completion of this work. Therefore, it is very important to ensure the regular operation of the water supply valves in the pipe network. The operation and management of water supply valves are related to the production and life of thousands of people, and we should attach great importance to them.
 
Operation management of water supply valves
 
The water supply valve is an important component of the water supply network, and it plays a key role in the daily water supply pipeline stopping and resuming work. Therefore, we should pay attention to the operation and management of valves in the water supply network. To ensure that the water supply valve can keep a good running state, first of all, it is necessary to ensure the normal use of the valve from the material and select qualified products; Secondly, in the process of construction and installation, strictly follow the construction specifications to ensure the normal operation of the newly-built valves; The most important thing is to establish and improve the routine inspection and maintenance system of valves after they are accepted and put into operation.
 
Basic requirements of water supply valves operation management
 
1. Accuracy of basic data of water supply valves In daily operation and management, basic data of valves are required to be complete and accurate, including instruction manual of valves, electronic completion drawing of the water supply network, three-line drawing of valve position, inspection and maintenance records of valves, etc. The place name, address, landform and river line coordinates of the third line of the gate card position drawing are required to be accurate.
 
2. Safety and operability of valve wells
Masonry of the valve well room shall conform to the specifications and keep the well room clean and tidy. Cement mortar shall be used for jointing the inner and outer shaft walls. When the plaster is required, plaster shall be compacted by layers. The valve manhole cover shall use the uniform specification pipe lock box specified by the company, and all pipe lock boxes shall be in a state of convenient opening and closing (no illegal buildings or other covers on it).
 
3. Integrity of water supply valve function
The water supply valves shall be opened and closed normally by the operators, and other valves shall be kept open except for special valves such as water discharge valves and valves that control the boundaries of the water supply area.
 
Establish valve data database, strengthen inspection and maintenance
 
After the early construction of the water supply valve is qualified, the later operation management is very important. In order to continuously improve the operation and management of valves, we have established a database of basic information on valves, combined with the inspection and maintenance records of valve operators, updated the data in real-time, and strengthened the operation and management of valves by using computer information technology.
 
1. Establish the basic data database of valves.
First, file the basic data of qualified valves, and establish the database of basic data of valves. In the basic data database of each valve, the attribute information of the valve will be recorded in detail, including the type, specification and model of the valve, manufacturer, installation date, construction unit, opening and closing times, operation records, inspection and maintenance records, etc.
 
2. Establish valve operation records and patrol maintenance system, and update the basic data database.
After establishing the basic data database of water supply valves, it is necessary to constantly update and maintain the valve data. Through the valve operation records and regular inspection and maintenance records, the problems existing in the running valves can be found in advance, and timely measures can be taken to deal with them, so as to achieve the goal of constantly updating and maintaining the basic data database of valves. With the development of urban construction, the valve will be buried in the well, and the soil in the well will be piled up, which will cause the valve to be inoperable. Therefore, it is necessary to maintain the good operability of the valve through routine inspection and maintenance. The standard requirements for routine valve inspection are as follows:
① Check the place name, address, landform and river line coordinates of the valve on the three-line diagram (the coordinate line should choose a permanently fixed object), and check the valve attribute data (caliber, style, etc.).
② Check whether the pipe brake box is higher (lower) than the road surface, and check whether the pipe brake box is in good condition.
③ Check whether the valves and nearby pipelines are enclosed and whether the valves are leaking.
 Check whether the valve well chamber is standard and whether the well should be dredged. The criterion of whether the well needs to be cleaned is: the upper cover of the valve or the second clamp bar in the well room must be clearly visible to the naked eye.
⑤ Check whether the valve can be opened and closed normally and the state of the valve opening and closing, and keep it as it is. The routine inspection and maintenance of valves should find problems, register problems and deal with problems in time.
 
3. Use computer information technology to improve the operation and management level.
With the increasing number of water supply valves, the traditional management mode can no longer meet the requirements of modern water supply enterprises. At present, the development of computer information technology provides favorable conditions for the modern operation and management of water supply valves, and the water supply network information system is also applied in daily work. In our daily work, we break the traditional form of single-use of basic information of valves when the water supply is stopped, introduce a mobile APP program, and use the topology diagram of the water supply network and information system of the water supply network in CAD to assist management. The basic information of valves, topology diagram of the water supply network and information system of the water supply network form a trinity and apply it to the operation and management of water supply valves, and use computer information technology to continuously improve our management and service level.
 
Main problems and suggestions of water supply valve in the operation
 
1. Main types of water supply valves operated by the company
At present, the water supply valves operated by the company mainly include gate valves and butterfly valves. Butterfly valves are mainly used in large-diameter valves (diameter over 500mm) in operation. There are two types of butterfly valves, one is horizontal and the other is vertical. There are two types of butterfly valve seals, one is a soft seal and the other is a hard seal. Gate valves are mainly used in small-bore valves (diameter 500mm and below) in operation. There are two main types of gate valves, one is vertical and the other is horizontal. The vertical gate valve is mainly used for the water supply pipeline with a diameter below 500mm (including 500mm); Horizontal gate valves are mainly used in water supply pipelines with a diameter of 500mm or more, and there are two sealing types of gate valves, one is soft sealing and the other is hard sealing.
 
2. Main problems and suggestions for butterfly valves
After the old soft sealing butterfly valve runs for a long time, the rubber sealing ring is prone to aging, cracking, loosening and separation, which leads to the unsealing of the rubber sealing ring. After the valve is operated and closed in place, the water cannot be stopped. In case of this kind of problem, it is suggested to remove the valve and replace the rubber sealing ring or replace it with a new butterfly valve with a hard seal after the water supply pipeline is stopped. In the operation of the butterfly valve, it is easy to happen that the positioning bolt is not in place, the pointer is displayed in place, and the butterfly valve plate is not closed in place. Therefore, when the valve is closed, it is observed that the pointer is in the closed position, and it is thought that it is closed in place, but there is no water stop. In case of this kind of problem, it is suggested to loosen the positioning bolt, close the valve in place, and then adjust and reposition the positioning bolt and pointer. The strength of the worm gearbox and transmission device of some butterfly valves can't meet the requirements of use. When closing the butterfly valve, the butterfly valve plate has not been closed in place, and there is obvious water noise, but it is already laborious to close it again. If the force is applied continuously, the worm sleeve of the transverse transmission of the worm gearbox will crack, and the transverse transmission shaft will not drive the longitudinal transmission device, thus the butterfly valve cannot be normally closed. In case of this kind of problem, it is suggested to reinforce the box with an iron splint, and at the same time, it is suggested that the manufacturer should conduct a strict factory test on the valve to strengthen the strength of the transverse worm gearbox.
 
3. Main problems and suggestions for gate valves
In daily work, gate valves have good practicability and high reliability, but there are also some shortcomings. Old-fashioned gate valves, whose screw rods are mostly made of iron, have been in contact with water for a long time, and are seriously corroded and rotted, especially at the lower end of the screw rod. When the valve is closed to the end, the screw rod at the end of the screw rod decays, resulting in the so-called "wandering around" phenomenon, which leads to the valve not being closed and not being opened enough. In case of this problem, it is recommended to use a soft sealing gate valve with stainless steel or copper wire rod. Sundries are easily stuck in the slot of the old gate valve, which prevents the gate from closing and cannot be closed in place. In case of this kind of problem, it is suggested to open and close the gate repeatedly to let the water flow wash away the sundries in the gate slot; It's best to replace it with a soft-sealed gate valve without a gate slot when there is an opportunity.
 
The design structure of the old horizontal gate valves
The transmission device of the new butterfly valve is completely exposed (the transmission device of the new butterfly valve is sealed in the turbine box, which can avoid aging and corrosion). Because of its age, and abundant rainwater and groundwater in the south, the valve is immersed in water for a long time, causing serious corrosion and decay. As a result, when the closing is completed, the force on the transmission device is increased, the big and small umbrella gears are separated and out of gear, and the teeth of the big and small umbrella gears fall off seriously, resulting in the situation that the closing is not in place. Sometimes, the valve can be closed in place. However, after the completion of construction or emergency repair, when the valve is opened to restore the water supply, due to the unilateral pressure of the valve, the large and small gears are out of gear and cannot be opened due to excessive force in opening the valve. In case of this problem, it is suggested to increase the spacer spacing by using large and small umbrella teeth to ensure that the umbrella gear can be coupled in place so that the horizontal gate valve can be opened and closed normally. In daily work, the old horizontal gate valve should be moved regularly. During the activity, it is found that the valve switch does not move, so it should be repaired and replaced in time.
 
4. Main problems and suggestions in the operation of the water supply valve
In the process of closing the valve, we mostly use the method of counting the number of turns and listening to the sound to judge whether the valve is closed in place. However, in actual operation, it is found that many valves will still have underwater sound even if the number of turns has reached. When the water supply pipeline is cut by construction, there is not much flow in the pipeline, which does not affect the normal construction, indicating that the valve has been closed in place, but only water seepage due to structural deformation. The manufacturing materials of valves are mainly metal materials, and the expansion and contraction of metal materials are the largest among all kinds of materials. Therefore, it is basically impossible for water supply valves, especially large-diameter valves, to be watertight at all times. It is suggested that colleagues should not ask for no sound when closing the large-diameter valve, as long as it does not affect normal construction. If the valve is closed forcibly, the valve structure may be damaged. The hard seal butterfly valve has poor resistance to the sundries in the pipeline during use. Once a foreign body is stuck at the junction of the door panel and the central rotating shaft, it is difficult to wash away the foreign body by opening and closing the valve. It is suggested that colleagues should take repeated opening and closing actions to close the valve when closing the hard seal butterfly valve, instead of opening and closing the valve in place at one time, so as to avoid the phenomenon of damaging the valve sealing ring.
 
Conclusion
 
Due to the continuous development of Nanjing in recent years, our company has intensified the renovation of the pipe network. Every year, more than 400 valves with diameters below 500mm and more than 20 valves with diameters above 500mm are maintained and replaced. Through continuous maintenance and replacement of valves, it has provided a strong guarantee for the planned shutdown and rehabilitation of major pipeline projects of our company (such as the renovation of the Weiyi Expressway pipe network, the relocation and renovation of the tunnel network of Chengxi trunk road bridge, and the rapid renovation of Yangzijiang Avenue, etc.). In the routine maintenance and emergency repair of the pipeline station, the water supply valve is in good condition, which greatly shortens the maintenance time without water, reduces the company's economic losses, and further improves the company's economic benefits.
 
Establish the database of basic information on water supply valves, formulate the system of regular inspection of valves, and the valve workers regularly inspect and maintain valves in their daily work, actively discover problems in the operation of valves, and deal with them in time; Establish the operation record of water supply valve, and summarize the experience and lessons in the process of using the valve by analyzing the valve operation record data, so that valve workers can better understand the characteristics of the valve in the daily operation process, better guide the actual operation of the valve, and improve the operation and management quality of the valve.