Galvanized steel pipes are divided into cold-dip galvanized steel pipes and hot-dip galvanized steel pipes. Cold-dip galvanized steel pipes have been banned, and the latter is also recommended by the country to be temporarily used. In the 1960s and 1970s, developed countries in the world began to develop new pipes and gradually banned galvanized pipes. China's Ministry of Construction and four other ministries and commissions have also issued documents clarifying that galvanized pipes will be banned as water supply pipes starting in 2000. Galvanized pipes are rarely used in cold water pipes in newly built communities, and hot water pipes in some communities use galvanized pipes. Hot-dip galvanized steel pipes are widely used in fire protection, electric power and highways.
Applications
Hot-dip galvanized steel pipes are widely used in construction, machinery, coal mines, chemical industry, electric power, railway vehicles, automobile industry, highways, bridges, containers, sports facilities, agricultural machinery, petroleum machinery, exploration machinery, greenhouse construction and other manufacturing industries.
Galvanized steel pipe is a welded steel pipe with a hot-dip or electroplated zinc layer on the surface. Galvanizing can increase the corrosion resistance of steel pipes and extend their service life. Galvanized pipes are widely used. In addition to being used as pipeline pipes for general low-pressure fluids such as water, gas, and oil, they are also used as oil well pipes and oil pipelines in the petroleum industry, especially offshore oil fields, and as oil heaters and condensators in chemical coking equipment. Pipes for coolers, coal distillate wash oil exchangers, pipes for trestle pipe piles, and support frames for mine tunnels, etc.
Detailed introduction editor broadcast
hot dip galvanized pipe
Hot-dip galvanizing pipe reacts molten metal with an iron matrix to produce an alloy layer, thereby combining the matrix and the coating. Hot-dip galvanizing is to pickle the steel pipe first. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned in an aqueous solution of ammonium chloride or zinc chloride or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to in a hot dip plating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion, and long service life. The hot-dip galvanized steel pipe matrix undergoes complex physical and chemical reactions with the molten plating bath to form a corrosion-resistant zinc-iron alloy layer with a tight structure. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix, so it has strong corrosion resistance.
cold galvanized pipe
Cold-dip galvanized pipe is electro-galvanized. The amount of galvanizing is very small, only 10-50g/m2. Its corrosion resistance is much worse than that of hot-dip galvanized pipe. Regular galvanized pipe manufacturers, in order to ensure quality, most do not use electro-galvanizing (cold plating). Only small businesses with small scale and old equipment use electro-galvanizing, and of course their prices are relatively cheaper. The Ministry of Construction has officially announced that cold-galvanized pipes with backward technology will be phased out and cold-galvanized pipes are not allowed to be used as water and gas pipes. The zinc layer of cold-dip galvanized steel pipe is an electroplated layer, and the zinc layer is layered independently from the steel pipe matrix. The zinc layer is thin, and the zinc layer simply adheres to the steel pipe matrix and falls off easily. Therefore, its corrosion resistance is poor. In new residential buildings, it is prohibited to use cold-dip galvanized steel pipes as water supply pipes.
weight factor
use
Instructions for use
Galvanized pipes are often referred to as galvanized pipes. The iron pipes used for gas and heating are also galvanized pipes. Galvanized pipes are used as water pipes. After a few years of use, a large amount of rust will occur in the pipes. The yellow water flowing out will not only pollute the sanitary ware. , and mixed with bacteria that breed on the rough inner wall, corrosion causes excessive heavy metal content in the water, seriously endangering human health.
Production steps
The process flow is: clarinet - alkali washing - water washing - pickling - water rinsing - dipping agent - drying - hot dip galvanizing - external blowing - internal blowing - air cooling - water cooling - Passivation - Water rinsing - Inspection - Weighing - Storage.
skills requirement
1. Brand and chemical composition
The grade and chemical composition of the steel used for galvanized steel pipes should comply with the grade and chemical composition of the steel used for black pipes specified in GB/T3091.
2. Manufacturing method
The method of manufacturing the clarinet (furnace welding or electric welding) is chosen by the manufacturer. Galvanizing adopts hot dip galvanizing method.
3. Threads and pipe joints
(a) For galvanized steel pipes delivered with threads, the threads should be machined after galvanizing. Threads should comply with YB 822.
(b) Steel pipe joints shall comply with the provisions of YB 238; malleable iron pipe joints shall comply with the provisions of YB 230.
4. Mechanical properties The mechanical properties of steel pipes before galvanizing should comply with the regulations of GB 3091.
5. Uniformity of galvanized layer Galvanized steel pipes should be tested for uniformity of galvanized layer. The steel pipe sample shall not turn red (copper-plated color) when immersed in copper sulfate solution for 5 consecutive times.
6. Cold bending test: Galvanized steel pipes with a nominal diameter not larger than 50mm should be subjected to cold bending test. The bending angle is 90°, and the bending radius is 8 times the outer diameter. There is no filler during the test, and the welding seam of the sample should be placed on the outside or upper part of the bending direction. After the test, there should be no cracks or signs of zinc layer peeling off on the sample.
7. Hydraulic pressure test The hydraulic pressure test should be carried out on the black pipe, and eddy current flaw detection can also be used instead of the hydraulic pressure test. The size of the test pressure or eddy current flaw detection comparison sample should comply with the regulations of GB 3092. The mechanical properties of steel are important indicators to ensure the final performance (mechanical properties) of steel.
Mechanical propertiesTensile strength (σb): The stress (σ) obtained by dividing the maximum force (Fb) that the sample endures when breaking during the stretching process by the original cross-sectional area of the sample (So) is called the tensile strength. Tensile strength (σb), unit is N/mm2 (MPa). It represents the maximum ability of a metal material to resist damage under tension. In the formula: Fb--the maximum force endured when the sample is broken, N (Newton); So--the original cross-sectional area of the sample, mm2.
Yield point (σs): For metal materials with yield phenomenon, the stress at which the sample can continue to elongate without increasing the force (remaining constant) during the stretching process is called the yield point. If the force decreases, the upper and lower yield points should be distinguished. The unit of yield point is N/mm2 (MPa). Upper yield point (σsu): the maximum stress before the specimen yields and the force decreases for the first time; Lower yield point (σsl): the minimum stress in the yield stage when the initial instantaneous effect is not considered. In the formula: Fs--yield force (constant) during the tensile process of the sample, N (Newton) So--original cross-sectional area of the sample, mm2.
Elongation after breaking: (σ) In the tensile test, the percentage of the increased length of the gauge length of the sample after breaking to the original gauge length is called elongation. Expressed by σ, the unit is %. In the formula: L1--the gauge length of the specimen after breaking, mm; L0--the original gauge length of the specimen, mm.
Shrinkage of area: (ψ) In the tensile test, the percentage of the maximum reduction of the cross-sectional area at the reduced diameter after the specimen is broken to the original cross-sectional area is called the shrinkage of area. Expressed by ψ, the unit is %. In the formula: S0--original cross-sectional area of the sample, mm2; S1--minimum cross-sectional area at the reduced diameter after the sample is broken, mm2.
Hardness index: The ability of a metal material to resist the indentation of the surface by hard objects is called hardness. According to different test methods and application scope, hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. There are three commonly used hardnesses for pipes: Brinell, Rockwell, and Vickers hardness.
Brinell hardness (HB): Use a steel ball or carbide ball of a certain diameter to press into the sample surface with a specified test force (F). After the specified holding time, remove the test force and measure the indentation diameter on the sample surface. (L). Brinell hardness value is the quotient obtained by dividing the test force by the surface area of the indented sphere. Expressed in HBS (steel ball), the unit is N/mm2 (MPa).
Performance impact
(1) Carbon; the higher the carbon content, the higher the hardness of the steel, but the worse its plasticity and toughness.
(2) Sulfur is a harmful impurity in steel. Steel with higher sulfur content is prone to embrittlement when pressure processing at high temperatures, which is usually called thermal embrittlement.
(3) Phosphorus tends to significantly reduce the plasticity and sturdiness of steel, especially at low temperatures. This phenomenon is termed your frosty brittleness. In high-quality steel, sulfur and phosphorus must be strictly controlled. But on the other hand, low carbon steel contains high levels of sulfur and phosphorus, which can make it easy to break during cutting, which is beneficial to improving the machinability of steel.
(4) Manganese; it can improve the strength of steel, weaken and eliminate the adverse effects of sulfur, and improve the hardenability of steel. High-alloy steel (high manganese steel) with high manganese content has good wear resistance and other physical properties.
(5) Silicon; it can increase the hardness of steel, but the plasticity and toughness decrease. Steel used for electrical engineering contains a certain amount of silicon, which can improve the soft magnetic properties.
(6) Tungsten; can improve the red hardness and thermal strength of steel, and can improve the wear resistance of steel.
(7) Chromium: It can improve the hardenability and wear resistance of steel, and can improve the corrosion resistance and oxidation resistance of steel.
(8) Zinc; in order to improve the corrosion resistance, general steel pipes (black pipes) are galvanized. Galvanized steel pipes are divided into two types: hot-dip galvanizing and electric steel zinc. Hot-dip galvanizing has a thick zinc layer and electro-galvanizing has low cost, so galvanized steel pipes are available.
Zhengde Galvanized steel pipes are divided into cold-galvanized pipes and hot-dip galvanized pipes. According to the shape, they are divided into galvanized round pipes and galvanized square rectangular pipes. Both the substrate and the coating are combined. Hot-dip galvanizing is to pickle the steel pipe first. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned by ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to hot-dip coating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
| DN |
outer diameter |
Ordinary steel pipe |
Thickened steel pipe |
| MM |
MM |
Deviation |
Thickness |
welded pipe(kg/m) |
Galvanized pipe(kg/m) |
Thickness |
welded pipe(kg/m) |
Galvanized pipe(kg/m) |
| MM |
Deviation |
MM |
Deviation |
| 6 |
10.2 |
|
2.0 |
|
0.40 |
0.4256 |
2.5 |
|
0.47 |
0.50 |
| 8 |
13.5 |
|
2.3 |
+12%
-15% |
0.62 |
0.64 |
2.75 |
+12%
-15% |
0.73 |
0.75 |
| 10 |
17 |
|
2.3 |
0.82 |
0.84 |
2.75 |
0.97 |
1.00 |
| 15 |
21.3 |
±0.5mm |
2.8 |
1.26 |
1.30 |
3.25 |
1.45 |
1.49 |
| 20 |
26.8 |
2.8 |
1.63 |
1.68 |
3.50 |
2.01 |
2.07 |
| 25 |
33.5 |
3.3 |
2.42 |
2.49 |
4.00 |
2.91 |
3.00 |
| 32 |
42.3 |
3.3 |
3.13 |
3.22 |
4.00 |
3.78 |
3.89 |
| 40 |
48 |
3.5 |
3.84 |
3.96 |
4.25 |
4.58 |
4.72 |
| 50 |
60 |
±1% |
3.5 |
4.88 |
5.03 |
4.50 |
6.16 |
6.34 |
| 65 |
75.5 |
3.8 |
6.64 |
6.84 |
4.50 |
7.88 |
8.12 |
| 80 |
88.5 |
4.0 |
8.34 |
8.59 |
4.75 |
9.81 |
10.10 |
| 100 |
114 |
4.0 |
10.85 |
11.18 |
5.00 |
13.44 |
13.84 |
| 125 |
140 |
4.5 |
15.04 |
15.49 |
5.50 |
18.24 |
18.79 |
| 150 |
165 |
4.5 |
17.81 |
18.34 |
5.50 |
21.63 |
22.28 |
Our Advantages
Galvanized round pipe
Galvanized round pipe is a common building material, mainly used in indoor and outdoor pipes, electrical wiring, ventilation pipes and mechanical structures and other fields. It has the characteristics of corrosion resistance, wear resistance, high strength, easy processing and installation, so it is widely used in various fields. In the field of construction, galvanized round pipes are mainly used for water and electricity pipes, HVAC systems and fire pipes, etc.; in terms of mechanical structures, they can be used as machine parts, auto parts and steel structures; in terms of furniture manufacturing, they can be used for manufacturing Table chairs and bed frames etc. In short, galvanized round pipes are very versatile and can meet the needs of various fields.
Galvanized Square Tube
Galvanized square pipe is a kind of steel pipe with anti-corrosion function, which is suitable for construction, structure, electrical,
Public services, automobile manufacturing and many other industries. Specific uses include:
1. Construction field: underground pipelines, outdoor and indoor building pipelines, building structures, decorative materials
wait.
2. Electrical field: power lines, communication lines, cable sheaths, generator sets, etc.
3. Machining: Simple operation and convenient operation, so it is widely used in machine tools, automobile manufacturing,
Food machinery and other fields.
4. Public services: highway tunnels, green belts, park squares, etc.
Qquality assurance
To choose a steel pipe company with product quality assurance, judge whether the company meets the relevant national production standards and quality standards by inquiring about the company's production license certificate, quality certification certificate and other details. Secondly, pay attention to the quality of the steel pipe, whether there are cracks, bubbles and other defects on the surface, and whether the product identification is complete and clear. In the process of use, it is also necessary to pay attention to regular cleaning to prevent the steel pipe from rusting and other phenomena, so as to prolong the service life of the steel pipe.
Galvanized steel pipe application
Galvanized steel pipe refers to a pipe coated with a layer of zinc on the surface of ordinary steel pipes to form a protective layer to prevent corrosion of steel pipes. Its corrosion resistance and mechanical properties are much better than clarinet and seamless steel pipes, and its appearance is more beautiful. It is widely used in construction, machinery, chemical industry, electric power and other industries. Zhengde galvanized steel pipe is a commonly used building material and is widely used in construction, industry and rural areas. For steel pipes, safety and quality are the most critical factors. The standard is to ensure the safety, quality and order of steel pipes.
Quality first: production and inspection in strict accordance with production standards;
Price advantage: discounts based on real market prices;
Transaction security: There will be no loss of customer funds;
After-sales guarantee: the customer's problem is our problem;
Long-term cooperation: quality assurance, price advantage, sincere service can last for a long time.
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Company Profile
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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