Maintenance and repair of heating system pipe network?

What is the specific content of maintenance and overhaul of heating system pipe network? Zhong Da Consulting will answer your questions below.

The management and maintenance of heating operation is a long-term, meaningful and sustainable work, which is the premise of inheriting and developing heating work better. It is the key to the sustainable development of each heating enterprise and the key to reducing costs and increasing efficiency in the heating industry. Therefore, it is necessary for us to study and discuss together today. Further improve our management and maintenance level and lay the foundation for the smooth implementation of heating work.

1. Maintenance of heating system pipe network

The maintenance management of heating system includes the maintenance management before operation, during operation and after shutdown, as well as the anti-scaling and anti-corrosion of the system. For outdoor heating pipe network, there are many ways of operation adjustment, such as quality adjustment, quantity adjustment and intermittent adjustment. Quality adjustment is realized by adjusting the supply and return water temperature of the system by increasing or decreasing the number of boilers put into operation or adjusting the combustion temperature of the furnace under the condition that the circulating flow of the pipe network is unchanged. Through the valves on the inlet and pipe network of each user, or the opening of the distribution valve at the water separator and water collector of the boiler room, and the operation of circulating pumps with different flows, the quantity can be adjusted (without changing the heating water temperature). By observing the thermometer on the water separator and the thermometer on the return pipe of the water collector, it can be judged whether the supply and return water temperature of each user meets the requirements; Intermittent adjustment is adjusted by changing the heating time and heating times every day.

It should be pointed out that it is unfavorable to adjust the users of hot water heating by reducing the circulating water volume and increasing the temperature difference between supply and return water. For example, in a double-pipe system, increasing the temperature difference between supply and return water will inevitably increase the gravity circulation pressure difference of the system, which is more likely to cause vertical imbalance, while using a smaller temperature difference and increasing the circulating water volume will help to weaken the vertical imbalance; For the vertical single pipe system, the heat transfer coefficient k of the upper and lower radiators decreases with the decrease of vertical water temperature. When the outdoor air temperature increases and the water supply temperature decreases, the k values of the upper and lower radiators also decrease, and the decrease rate of the upper radiator is greater than that of the lower radiator, so it is more likely to appear the phenomenon of upper cooling and lower heating. On the other hand, if the method of increasing the circulating water volume of the system and reducing the temperature difference between supply and return water is adopted for adjustment, the influence of the upper and lower K values will be relatively weakened.

1. 1 Maintenance and management before operation

Before the annual operation period of heating system comes, all heating pipes and cooling equipment must be overhauled, and internal dirt and surface dirt must be cleaned. And test the water of the system, check and repair the leakage point to ensure that the system can be put into normal operation.

1.2 Maintenance and management during operation

The maintenance and management of heating system should formulate patrol inspection system according to the specific conditions of each unit, and make operation records, so as to master the operation of the system, prevent leakage and freezing, and solve problems in time when found.

1.3 Maintenance management after shutdown

Maintenance after shutdown has two meanings: one is to prepare for maintenance; The second is to lay a good foundation for heating in the coming year. Maintenance is mainly to check the system, it is best to stop the machine before starting the inspection. The main contents of the inspection are as follows: ① After the shutdown, all pipes should be carefully inspected, and the seriously corroded pipes should be replaced; Pipes that have been in operation for many years and have been replaced several times should be inspected by water pressure test. (2) After shutdown, all control components, including valves, pressure reducing valves and traps in the steam system, should be kept at the second level and removed for disassembly and cleaning. Inspect and clean the detachable parts that are really difficult to disassemble. (3) After the hot water system is shut down, all the water in the system should be discharged, cleaned with water, and finally filled with qualified water (must be filled) to prevent the air in the system from corroding the pipeline. (4) After cleaning the system, finally clean the decontamination device to keep it clean. ⑤ When cleaning accessories, be careful, soak them in kerosene, and then wipe them clean. The exterior and interior should be sealed with butter or engine oil, and the shell part should be painted to prevent corrosion. For parts that move frequently, pay attention to replacing new packing and oil seal. ⑥ Grind the control parts with defects such as looseness and failure, and replace them as required. ⑦ Check and clean the expansion water tank and the condensation water tank, wipe them clean when necessary, and do anti-corrosion treatment.

2. Maintenance of heating pipeline

Common problems of thermal pipelines include: pipeline rupture (overpressure burst, frost crack), pipeline corrosion, water leakage and steam leakage at the joint between pipes, and insulation structure falling off of pipelines.

2. 1 pipeline crack and corrosion repair

During the shutdown of the heating system, if the cracks along the pipeline weld are not long, welding can be carried out; If it is too long, it can be replaced with a new tube and welded; If the pipe section is not long, the whole pipe section can be replaced by threaded connection.

2.2 Repair of pipeline water leakage and steam leakage

According to the severity of water leakage or steam leakage, determine the repair method. Leakage caused by local corrosion can be repaired by repair welding. It is difficult to repair the leaking water in the plumbing pipes, or the pipes that can't stop can be repaired by sticking.

2.3 Repair of water leakage or steam leakage at pipe joints

Pipe joints are usually connected by threads, flanges, unions and filaments.

2.3. 1 thread leakage

Generally, it occurs at the pipe hoop (inner wire), tee joint, bend and other places connected with branch pipes or risers. The main reason for water leakage is that the thread quality is not high or corroded during installation, or it may be that the thread is not tightened. The repair method is to take it apart and deal with it according to different situations. Seriously corroded pipes should be replaced.

2.3.2 Treatment of water or steam leakage of loose joint (free joint)

The reason of loose joint leakage is that the gasket is broken or the pipeline is damaged by impact. When repairing, you can tighten the bushing first. If it fails, you need to replace the gasket. After cleaning the old pad with an old saw blade (or glass, knife, etc.). ), put on a new pad soaked in oil.

2.4 Repair of flange leakage

When installing the flange, the bolt is slightly tightened, and the flange pad is easily corroded by water or steam in the pipeline. Once subjected to external force, it is easy to cause leakage. The main method is to replace the flange gasket, tighten the bolt diagonally, and then check it again by one person. What needs to be emphasized here is that in case of flange leakage during the operation of the heating system, the thermal expansion and cold contraction of the pipeline should be considered during the operation and maintenance. Because most repairs are carried out when the temperature and pressure of the pipeline are low, the gap between flanges is large. Although the bolts are tightened, the gap between flanges is smaller after the pipeline temperature rises, and the bolts are in a relaxed state, so more serious leakage will occur when the pressure in the pipeline rises. The correct method is to tighten the system several times after routine maintenance, as the system resumes operation, until the system runs completely normally.

3. Eliminate hydraulic imbalance and realize energy-saving operation of heating system.

How to deal with the imbalance of system resistance is the key to energy-saving operation of heating enterprises. It is impossible for any heating system to solve the problem of hydraulic balance in operation through the design of pipe network, thermal power station and heat users, the layout of pipe network, hydraulic calculation, pipe diameter, pipe fittings and equipment selection. The key to solve this system imbalance is to carefully adjust the balance during the operation of the heating system, and it is possible to gradually approach the hydraulic balance through different adjustment means. In the actual heating project, due to the different circulation modes of each heating pipe network and indoor heating system, different radiator selection forms (parameters), different installation methods and different correction coefficients, the resistance of the system is different. Therefore, different regulation methods should be implemented according to various heating forms and heat load requirements. For the directly connected heating system, quality adjustment, quantity adjustment and phased change of flow quality adjustment are adopted. For indirect heating system, due to the large number of heat exchange stations, the secondary network flow of each heat exchange station is different, so we should not adjust it according to the water supply temperature or backwater temperature of the secondary network, but according to the average water supply temperature and backwater temperature of the secondary network.

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