Professional manufacturer of ductile pipe and well cover

Consulting phone:+86 1863560866
Standard of execution

Production standard for ductile iron pipes:

ISO2531/GB/T13295/EN545/EN598/AWWA C151/KSD4311 Our company's implementation: ISO2531/GB/T13295/EN545/EN598 water pressure testing standards are: DN80-300 5.0Mpa, pressure 15s DN350-600 4.0 Mpa, pressure 15s DN700-800 3.2 Mpa, pressure 15s Our company's water pressure test has a holding time of 5 seconds longer than the national standard time.
Tooling Process

Complete professional equipment to ensure quality 1.Blast furnace and blast furnace molten iron Our company adopts blast furnace-electric furnace double-link short-flow continuous casting technology. Our existing blast furnace capacity is 318 cubic meters, and blast furnace smelting can improve smelting efficiency and reduce cost. 2.Electric furnace temperature regulation and tempering & spheroidizing treatment After the molten iron smelting is completed, the raw materials (scrap, molten iron, recycled materials, etc.) are added to the induction furnace, and the composition is adjusted to meet the process requirements. Then, when the temperature is appropriate, a spheroidizing agent is added for spheroidization. In the spheroidizing process, a 15-20 mm spheroidizing agent (rare earth magnesium alloy FeSiMg8Re3-B, generally added in an amount of 1.0 to 1.6%) is placed in a spheroidizing bag, and a covering agent is added according to different temperatures of the molten iron. When spheroidizing treatment, 2/3 or 3/4 of the total amount of molten iron should be added first, so that the spheroidizing agent and the molten iron can be fully reacted. After the molten iron tumbling phenomenon stops, the remaining molten iron is injected, and a certain amount is rushed at the same time. Inoculant (75SiFe, added in an amount of 0.4 to 0.6%) promotes spheroidization of graphite. The suitable spheroidization temperature in the spheroidization process is about 1400 °C, and the excessively high spheroidizing agent loses too much. Too low is not conducive to oxide slag and gas floating.

3.Centrifugal casting

The socket core is mounted on the centrifuge, and the spheroidized molten iron is poured into the quantitative package. According to the process requirements, the amount of the inoculant and the tube mold powder is set, the rotation speed of the centrifuge, the walking speed and the turning speed of the quantitative package are set. The molten iron is cast in a rotating tube mold with the inversion of the quantitative package and the walking of the centrifuge, and solidifies into a tube. In the centrifugal casting process, the smoothness and roundness of the socket core directly determine the quality of the socket; the tube powder is added to improve the smoothness of the tube body and reduce the formation of pores; the rotation speed of the centrifuge and the fan-shaped package The turning speed determines the wall thickness and weight of the cast pipe; when the molten iron solidification molding centrifuge stops rotating, the socket and the pipe body are poured with a water injection gun. When the pipe body temperature reaches 600 ° C, the pipe is removed from the pipe clamp. The tube mold is pulled out and sent to the heat treatment department. Before entering the heat treatment, metallographic detection is performed to check whether the spheroidization rate is up to standard. Spectrometer (The spectrum analyzer currently used by our company is imported from Germany and can detect C (carbon), Si (silicon), S (sulfur), P (phosphorus), Mn (manganese), Mg (magnesium) in molten iron. Twenty chemical elements such as trace element Ti (titanium).

4. Heat treatment

The tube that has passed through the centrifuge will have a large amount of cementite and pearlite in the gold image structure, and the tube will be annealed through an annealing furnace to transform the structure into a ferrite-based ductile iron pipe. The annealing furnace is 65 meters long, which makes the annealing process more gentle. The annealing process is divided into five temperature zones: heating, heat preservation, quenching, slow cooling and post-cooling. The high temperature process is to eliminate cementite, and the low temperature process is to eliminate pearlite. After the annealing treatment, the temperature at which the tube is discharged is not higher than 650 ° C, and the entire annealing time is generally completed within 42 to 56 minutes. After annealing, the ring is cut, and the tensile strength (≥420MPA), elongation (≥10%) and Brinell hardness (≤230HBW) of the cast tube are tested. The test requirements are in accordance with GB/T228.1-2010, GB/ T231.1-2009 to implement.

5. Spray zinc To enhance the corrosion resistance of the cast tube, zinc is sprayed onto the surface of the tube using an arc technique. The method for detecting the thickness of zinc spray is as follows: a standard sample is attached to the bulb to be sprayed with a metered strip, and the weight per unit area is calculated by measuring the difference in weight before and after spraying the sample. And proportional to the standard area of zinc weight, and then adjust the zinc spray parameters according to the difference value to ensure zinc spray standards.

6. Rounding and polished

In order to ensure the surface quality of the pipe and the installation size of the socket, the socket and the inner wall of the pipe are polished and cleaned to ensure the installation of the pipe and the requirements of the next process. In the whole process of gardening and grinding, it is necessary to test the socket, the socket and the roundness. If the tube is found to have a small inner diameter of the socket or a large outer diameter of the socket, it needs to be repaired; if it is found that the tube has an ellipse and the deformation exceeds the specified condition, the campus machine must be used for the whole garden correction; manual cleaning of the socket and the socket Edge and burr, sanding the socket and socket with a grinder and cleaning it up; in the production process, we will carry out the whole garden and sanding one by one, and chamfer the end of the socket.

7. Water pressure test

During the hydrostatic test, the pipe bearing and the two ends of the socket and the fixed plate of the hydraulic press are sealed by a sealing ring. After the water filling-exhaust-pressurization-pressure keeping process, the dwell time is about 15 seconds, the maximum allowable The test pressure is 5.5 MPA-6 MPA (55 kg - 60 kg). Our factory adopts electronic pressure gauge, which can better guarantee the packing pressure time and stable pressure bearing capacity of the pipe during the test. Other plants use ordinary pressure gauges, which can not guarantee the pressure holding time and stability of the pressure bearing capacity of the pipe. 8. Lining cement and health In order to avoid pipe fouling and increase the water resistance, reduce the service life of the pipe, the pipe is lined with cement according to ISO2531 and ISO4179 standards. After that, it is sent to the health to make the tube lining have a certain strength before being sent to the coating process. Cement lining materials include cement, sand and water. The cement mortar lining is a dense, uniform lining covering the inner surface of the straight pipe. The pipe to be coated is transported to the fabric station, and the socket and the socket are manually sealed, and the cement mortar is injected through the cloth bar to make it evenly distributed in the inner cavity of the cast pipe. The well-fed tubes are sent to the centrifugal dewatering station by a step conveyor, and the moisture in the cement mortar is separated under the rotation of the high-speed centrifuge. After the cement inner liner of the pipe is coated, the pipe is removed from the centrifugal dewatering station and the plugs on both ends of the pipe are manually removed. When the cement-coated pipe is steamed, its curing temperature is generally controlled at 40-50 °C, the relative humidity is controlled at 70%, and the curing time is controlled for 8-12 hours (the longest time is spent in the whole process) of). If the health temperature and relative humidity are not well controlled, the lining may be foamed or cracked.

9. Re-grind the cast pipe that has been cured for health, remove the floating ash, and pass the zinc coating on the socket and spray the asphalt paint on the pipe body. Spraying asphalt paint is subject to three steps of preheating (70-80 ° C) - painting - drying (50-60 ° C), but many manufacturers will save the cost of drying, the steps of drying with a drying oven, Let the pipe body dry naturally, which will cause the dry pipe body to be dirty and affect the appearance quality. Reliable equipment with professional management, Kun Teng cast pipe is definitely a reliable manufacturer in China

Pipe production process
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ADD: Kun Peng Fortune Center, Jin Chen, Shanxi Cell: 18635600991 Fax: 0356-2057132 Email:

Product Category

Ductile iron pipe
Ductile iron fitting
Flexible interface Ductile iron drain
Drain fitting