Ductile iron castings are a kind of pipe products commonly used in water pipe routing in modern construction industry. They are not only strong in compression resistance, but also strong and durable. However, if they are not well maintained in the process of installation and use, their service life is quite short. It can be said that the maintenance of nodular graphite pipe should always start from its type selection. Before the start of the project, we should have a naked eye inspection on the parts we need, such as pipe fittings, rubber rings, elbows and so on, to avoid the use of diseased parts. The key point of maintenance is the acceptance work time. We should pay attention to the influence of the long-term stable operation of the socket apron under the pipe (drain pipe) and so on. We should strive to have no debris in these aspects of the socket. The rubber ring has been beaten by a rubber hammer, which is not warped or twisted, and is evenly stuck in the groove.

In the production process of ductile iron castings, it is inevitable that some micro-cracks (flake graphite is actually a kind of micro-crack source, slag inclusion, pore, shrinkage and oxide, etc.) will occur, which will result in a small stress set and greatly reduce the mechanical properties of pipes. Ductile iron castings are brittle materials, which may be damaged by slight jumping during transportation. In the installation operation, cracking, smashing, etc., restoring cracks continue to occur and develop. When cast iron pipes are put into use, they only bear static force on the surface, but in fact bear complex dynamic loads. When the crack develops to a certain extent, the material will crack. Some installation methods that do not conform to the operation rules aggravate the development and destructive effect of the above defects.

Ductile iron pipe has high corrosion resistance, and the corrosion resistance of ductile iron pipe is more than 30 times that of steel. Ductile iron pipe is lined with cement or resin and coated with asphalt paint, which solves the problems of internal and external corrosion. Gray iron pipe and steel pipe can not be solved. Therefore, users do not need to take any anti-corrosion measures. It also prevents secondary pollution of water quality.

The contact is flexible and has good adaptability. The connecting pipe of ductile iron castings is a push joint or rubber gasket joint for mechanical seal, which has good sealing and ductility. No welding is necessary. The designed deflection is 3-5 degrees, and the number of parts needed can be reduced. Joints can absorb the pressure caused by foundation settlement and prevent pipeline rupture.

Stacking requirements for ductile iron castings:

1. The principle requirement of stacking is to stack according to varieties and specifications under the condition of stable and guaranteed stacking. Different kinds of materials should be stacked separately to prevent confusion and mutual corrosion.

2. It is forbidden to store articles with corrosive effect on steel near the stack.

3. The stacking bottom should be padded high, firm and flat to prevent material from damp or deformation.

4. The same material is stacked separately according to the storage order. Ductile iron pipe is easy to implement the principle of first-in-first-out.

5. Shape steel stacked in the open air, with wooden mats or strips beneath, and slightly inclined stacking surface to facilitate drainage, and pay attention to placing materials straight to prevent bending deformation.

6. Stacking height, manual operation not more than 1.2m, mechanical operation not more than 1.5m, stacking width not more than 2.5m.

7. There should be a certain channel between the stack and the stack. The checking channel of ductile iron pipe is generally 0.5m. The access channel depends on the size of the material and the transport machinery, generally 1.5-2.0m.

8. Pad the bottom high, if the warehouse is the cement floor of Chaoyang, pad 0.1 M high; if it is the cement floor, pad 0.2-0.5 m high. If it is an open-air site, the height of cement floor cushion is 0.3-0.5m, and that of sand and mud surface cushion is 0.5-0.7m.

Checking items for ductile iron castings:

1. Mould management, the mould should be well maintained and maintained, not with obvious defects, in order to avoid affecting the surface quality of pipe fittings.

2. Production capacity, there should be a large warehouse to store pipe fittings for routine use, the purchaser should pay attention to this issue in the inspection records. It is very important to have the ability to supply in time.

4. Ductile iron pipe weight control system, the process should ensure that the weight of pipe fittings within the standard tolerance range.

5. Hydraulic test. Every fittings, regardless of its diameter, should be tested by hydraulic test or equivalent effect test.

6. The use of materials should be stable and clean. Overuse of recycled raw materials by some manufacturers to reduce costs will inevitably lead to quality problems.

7. Dimension testing. The dimensions of each pipe should be checked with standard gauges to meet the required tolerances.

8. The thickness of the anticorrosive layer and the internal and external anticorrosive layer shall meet the requirements of the standards.

9. For the problem of the thickness of the fittings (usually K12), some manufacturers believe that the sufficient thickness of the fittings can compensate for the strength of the material itself, or even lack the control of raw materials. Therefore, the total quality management system should be implemented to ensure the quality of each pipe fitting.