Ductile iron pipes refer to pipes that are cast by high-speed centrifugal casting using a centrifugal ductile iron machine after adding nodulizing agent to cast molten iron above No. 18. They are referred to as ductile iron pipes, ductile iron pipes and ductile cast pipes. It is mainly used for the transportation of tap water and is an ideal material for tap water pipelines.
The essence of cast iron steel pipe is ductile iron pipe. Because ductile iron pipe has the essence of iron and the performance of steel, it is called this. The graphite in ductile iron pipes exists in spherical form, and the size of graphite is generally grade 6-7. The quality requires that the spheroidization level of cast iron pipes be controlled to level 1-3, with a spheroidization rate of ≥80%. Therefore, the mechanical properties of the material itself have been better improved, and it has the essence of iron and the properties of steel. After annealing, the metallographic structure of ductile iron pipe is ferrite plus a small amount of pearlite, and has good mechanical properties, so it is also called cast iron steel pipe.
Features: It has the nature of iron, the performance of steel, excellent anti-corrosion properties, good ductility, and easy installation. It is mainly used for water supply and gas transmission in municipal, industrial and mining enterprises.
Development History Editor Broadcast
In 1947, H. Morrogh of the United Kingdom discovered that when cerium was added to hypereutectic gray cast iron so that the content was above 0.02wt%, the graphite became spherical. In 1948, A. P. Ganganebin and others in the United States pointed out that magnesium was added to cast iron and then incubated with ferrosilicon. When the residual magnesium amount was greater than 0.04wt%, spherical graphite was obtained. Since then, large-scale industrial production of ductile iron has begun. The history of the use of cast iron pipes can be traced back to 1668, when a 21.14km water pipeline was built in the suburbs of Paris from the Seine River to Versailles. 300 years have passed. Except for the repair and replacement of some pipes and joints, the main body is still in use.
Current situation and prospects of ductile iron pipes in my country
my country's ductile iron pipe industry started in the early 1990s and developed rapidly with the strong support of the China Urban Water Supply Association. After nearly 30 years of practical use, its safety and practicality have been generally recognized by the water supply industry. In 2008, domestic Annual output has reached 2.2 million tons, 11 times that of 1990. Since my country is a country lacking water resources, with more than 600 water-deficient cities and more than 200 serious water-deficient cities, the water supply and water conservation industry is in the ascendant, and ductile iron pipes have broad development prospects. [1]
Features Editor Broadcast
Ductile iron pipe is a type of cast iron pipe. Quality requires that the spheroidization level of cast iron pipes be controlled to level 1-3 (spheroidization rate > 80%). Therefore, the mechanical properties of the material itself have been better improved, and it has the essence of iron and the properties of steel. The annealed ductile iron pipe has a metallographic structure of ferrite plus a small amount of pearlite. It has good mechanical properties, excellent anti-corrosion properties, good ductility, good sealing effect, and is easy to install. It is mainly used for water supply and gas transmission in municipal, industrial and mining enterprises. , oil transportation, etc.
There is a certain amount of spherical graphite distributed on the ferrite and pearlite matrix. According to the nominal diameter and elongation requirements, the proportion of ferrite and pearlite in the matrix structure is different. The proportion of small diameter pearlite Generally no more than 20%, and large diameters are generally controlled at around 25%.
Performance Editor Broadcast
Ductile iron pipe is a type of cast iron, an alloy of iron, carbon and silicon. Graphite in ductile iron exists in the form of spheroids. Generally, the size of graphite is grade 6-7. The quality requires that the spheroidization level of the cast pipe be controlled to grade 1-3 (spheroidization rate ≥80%). Therefore, the mechanical properties of the material itself The performance has been better improved, with the essence of iron and the performance of steel. The metallographic structure of the ductile iron pipe after annealing is ferrite plus a small amount of pearlite, and has good mechanical properties.
Ductile iron pipe is mainly called centrifugal ductile iron pipe. It has the essence of iron and the performance of steel. It has excellent anti-corrosion performance, good ductility, good sealing effect, and is easy to install. It is mainly used for water supply, gas transmission, and transportation in municipal, industrial and mining enterprises. Oil etc. It is the first choice for water supply pipes and has a high cost performance. Compared with PE pipes, ductile graphite pipes are simpler and faster to install than PE pipes in terms of installation time, and have better internal and external pressure resistance after installation; in terms of airtightness and anti-corrosion, ductile graphite pipes have better airtightness after installation, and are also The anti-corrosion performance can be improved through a variety of anti-corrosion methods; from the perspective of hydraulic performance, the specifications of ductile graphite pipes generally refer to the inner diameter, and the specifications of PE pipes generally refer to the outer diameter, because under the same specifications, ductile graphite pipes can achieve greater runoff; from In terms of comprehensive installation and maintenance costs, ductile graphite pipes have a more superior cost performance.
Selection suggestions
1. The selection of ductile iron pipes should be based on the specific conditions of the laying site and the interface form of straight pipes and accessories.
2. Rubber rings are usually made of NBR, SBR, EPDM and other materials.
3. Selection of coating: Choose an appropriate coating according to the internal and external conditions during use. The existing inner coatings are epoxy resin, polyurethane inner and outer coatings, PE film coatings and other new ductile iron pipe products. When selecting, you should understand their performance in detail.
advantage
In medium and low pressure pipe networks (generally used below 6MPa), ductile iron pipes have safe and reliable operation, low damage rate, convenient and fast construction and maintenance, and excellent anti-corrosion properties. The newly developed "Rock Shield" series of pipelines are suitable for trenchless construction and are widely used in pipeline construction across rivers, roads, and buildings. "Saizin" series pipelines use a special zinc-aluminum alloy external spraying process to improve the corrosion resistance of the pipeline several times and are widely used in construction in highly corrosive soils.
shortcoming
Generally not used in high-pressure pipe networks (above 6MPa). Because the pipe body is relatively heavy, machinery must be used during installation. If water leakage occurs after the pressure test, all pipes must be dug out, the pipes must be lifted to a height where the clamps can be placed, and clamps must be installed to prevent leakage.
Use bullet points to edit and broadcast
1. Trench excavation
The bottom width of the trench should be calculated according to the following formula: B=D1+2(b1+b2)
In the formula: B-The excavation width at the bottom of the pipeline trench (mm) D1-The outer edge width of the pipeline structure (mm) b1-The width of the working surface on one side of the pipeline (mm) b2-The support width on one side of the pipeline (mm)
2. Groove support
The design is based on factors such as trench soil quality, groundwater, groove section, load conditions, etc. It must be strong and reliable to prevent collapse, and the support must not hinder the lowering and stabilizing of the pipe.
3. T-joint pipes should be provided with buttresses at vertical or horizontal turns. The size of the buttress should be determined through calculation based on factors such as pipe diameter, rotation angle, and working pressure.
4. When transporting drinking water, pipelines should not pass through poison-contaminated areas. If they must pass through, protective measures should be taken.
5. All ductile iron pipelines with socket connections must be equipped with buttresses after calculation. Please refer to the National Building Standard Design Atlas 10S505 "Flexible Interface Water Supply Pipeline Buttresses".
6. The external anti-corrosion coating of ductile iron pipes should be galvanized and epoxy asphalt coatings or coatings with higher requirements according to the soil conditions of the place where the pipes are laid.
7. After the pipeline is installed and the pressure test passes, it should be flushed with low chloride ion water and disinfected with 0.03% potassium permanganate aqueous solution.
Anti-corrosion treatment editor broadcast
1. Asphalt paint coating
Asphalt paint coating is used on pipes carrying gas. Preheating the pipe before painting can improve the adhesion of the asphalt paint and speed up drying.
2. Cement mortar lining + special coating
This internal anti-corrosion measure is suitable for pipelines transporting sewage and can improve the corrosion resistance of the lining.
3. Epoxy coal pitch coating
Epoxy coal pitch coating is suitable for both gas pipelines and sewage pipelines. It is a two-component coating that has high adhesion and a very smooth surface
4. Epoxy ceramic lining
Epoxy ceramic lining is suitable for sewage pipes and gas pipes, but due to the difficulty and high cost of the manufacturing process, there are certain limitations in use. Epoxy ceramic lining has high adhesion and smoothness, and is a good anti-corrosion coating.
5. Aluminate cement coating or sulfate cement coating
These two special cement coatings are suitable for internal anti-corrosion of ductile iron pipes used in sewage pipes to improve their ability to resist the erosion of acid and alkali components in sewage.
6. Polyurethane coating
It is a new type of green special coating developed to meet the needs of environmental protection. It has good wear resistance and corrosion resistance.
Zhengde Ductile iron pipe is a type of cast iron, an alloy of iron, carbon and silicon. Graphite in ductile iron exists in the form of spheroids. Generally, the size of graphite is grade 6-7. The quality requires that the spheroidization level of the cast pipe be controlled to grade 1-3 (spheroidization rate ≥80%). Therefore, the mechanical properties of the material itself The performance has been better improved, with the essence of iron and the performance of steel. The metallographic structure of the ductile iron pipe after annealing is ferrite plus a small amount of pearlite, and has good mechanical properties.
Ductile iron pipe is mainly called centrifugal ductile iron pipe. It has the essence of iron and the performance of steel. It has excellent anti-corrosion performance, good ductility, good sealing effect, and is easy to install. It is mainly used for water supply, gas transmission, and transportation in municipal, industrial and mining enterprises. Oil etc. It is the first choice for water supply pipes and has a high cost performance. Compared with PE pipes, ductile graphite pipes are simpler and faster to install than PE pipes in terms of installation time, and have better internal and external pressure resistance after installation; in terms of airtightness and anti-corrosion, ductile graphite pipes have better airtightness after installation, and are also The anti-corrosion performance can be improved through a variety of anti-corrosion methods; from the perspective of hydraulic performance, the specifications of ductile graphite pipes generally refer to the inner diameter, and the specifications of PE pipes generally refer to the outer diameter, because under the same specifications, ductile graphite pipes can achieve greater runoff; from In terms of comprehensive installation and maintenance costs, ductile graphite pipes have a more superior cost performance. The inner wall is sprayed with zinc, cement mortar anti-corrosion materials, etc.
Selection suggestions
1. The selection of ductile iron pipes should be based on the specific conditions of the laying site and the interface form of straight pipes and accessories.
2. Rubber rings are usually made of NBR, SBR, EPDM and other materials.
3. Selection of coating: Choose an appropriate coating according to the internal and external conditions during use. The existing inner coatings are epoxy resin, polyurethane inner and outer coatings, PE film coatings and other new ductile iron pipe products. When selecting, you should understand their performance in detail.
| DN(mm) |
DE(mm) |
T(mm) |
kg |
kg/m |
| K8 |
K9 |
K10 |
K8 |
K9 |
K10 |
| 80 |
98 |
6 |
6 |
6 |
3.4 |
12.2 |
12.2 |
12.2 |
| 100 |
118 |
6 |
6 |
6.1 |
4.3 |
14.9 |
15.1 |
15.1 |
| 125 |
144 |
6 |
6 |
6.3 |
5.7 |
18.3 |
18.3 |
19 |
| 150 |
170 |
6 |
6 |
6.3 |
7.1 |
21.8 |
22.8 |
22.8 |
| 200 |
222 |
6 |
6.3 |
6.4 |
10.3 |
28.7 |
30.6 |
30.6 |
| 250 |
274 |
6 |
6.8 |
7.5 |
14.2 |
35.6 |
40.2 |
44.3 |
| 300 |
326 |
6.4 |
7.2 |
8 |
18.9 |
45.3 |
50.8 |
56.3 |
| 350 |
378 |
6.8 |
7.7 |
8.5 |
23.7 |
55.9 |
63.2 |
69.6 |
| 400 |
429 |
7.2 |
8.1 |
9 |
29.5 |
67.3 |
75.5 |
83.7 |
| 450 |
480 |
7.6 |
8.6 |
9.5 |
38.3 |
80 |
89 |
99 |
| 500 |
532 |
8 |
9 |
10 |
42.8 |
92.8 |
104.3 |
115.6 |
| 600 |
635 |
8.8 |
9.9 |
11 |
59.3 |
122 |
137.3 |
152 |
| 700 |
738 |
9.6 |
10.8 |
12 |
79.1 |
155 |
173.9 |
193 |
| 800 |
842 |
10.4 |
11.7 |
13 |
102.6 |
192 |
215.2 |
239 |
| 900 |
945 |
11.2 |
12.6 |
14 |
129 |
232 |
260.2 |
289 |
| 1000 |
1048 |
12 |
13.5 |
15 |
161.3 |
275 |
309.3 |
343.2 |
| 1200 |
1265 |
13.6 |
15.3 |
17 |
237.7 |
374 |
420.1 |
466.1 |
| 1400 |
1462 |
16 |
17.1 |
19 |
385.3 |
487 |
547.2 |
|
| 1600 |
1668 |
18.4 |
18.9 |
21 |
526 |
614.5 |
690.3 |
|
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Shandong Zhengde Metal Manufacturing Co., Ltd. is a production and sales company integrating hot-rolled steel coils, cold-rolled steel coils, galvanized steel coils, color-coated steel coils, section steel, steel pipes, steel wires, metal mesh, stainless steel, aluminum, copper and other metal products integrated large enterprises. Five production and sales bases have been formed in Binzhou, Liaocheng, Wuxi, Tianjin, Jinan and Tai'an, with more than 100 production lines, 4 nationally recognized laboratories, 2 technical engineering centers, and 5 enterprise technology centers. Products are exported to more than 50 countries and regions such as North America, South America, Europe, Africa, Oceania, Middle East, and Southeast Asia.
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