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環(huán)球新聞資訊，9月19日報道：鍍鋅鋼管分為冷鍍鋅鋼管、熱鍍鋅鋼管，冷鍍鋅鋼管已被禁用，后者還被國家提倡暫時能使用。六七十年代，國際上發(fā)達國家開始開發(fā)新型管材，并陸續(xù)禁用鍍鋅管。中國建設(shè)部等四部委也發(fā)文明確從2000年起禁用鍍鋅管作為供水管，新建小區(qū)的冷水管已經(jīng)很少使用鍍鋅管了，有些小區(qū)的熱水管使用的是鍍鋅管。熱鍍鋅鋼管在消防、電力和高速公路上有廣泛的應(yīng)用。

Global News, September 19, reported that galvanized steel pipes are divided into cold galvanized steel pipes and hot galvanized steel pipes. Cold galvanized steel pipes have been banned and the latter have been advocated by the state to be temporarily usable. In the sixties and seventies, developed countries began to develop new pipes and banned galvanized pipes in succession. China's Ministry of Construction and other four ministries have also issued a document stating that galvanized pipes have been banned as water supply pipes since 2000. Galvanized pipes are rarely used in cold water pipes in new residential areas, and galvanized pipes are used in hot water pipes in some residential areas. Hot dip galvanized steel pipes are widely used in fire fighting, electric power and highways.

Hot dip galvanized pipe is to make molten metal react with iron matrix to produce alloy layer, thus combining the matrix and plating layer. Hot dip galvanizing is to pickle the steel pipe first. In order to remove iron oxide from the steel pipe surface, after pickling, the steel pipe is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to a hot dip plating bath. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. The matrix of hot-dip galvanized steel pipe reacts with molten plating solution physically and chemically to form a corrosion-resistant zinc-iron alloy layer with tight structure. The alloy layer is integrated with pure zinc layer and steel pipe matrix, so it has strong corrosion resistance.

2、制造方法

黑管的制造方法（爐焊或電焊）由制造廠選擇。鍍鋅采用熱浸鍍鋅法。

Cold galvanized pipe
Cold galvanized pipe is electro - galvanized, with a small amount of galvanizing, only 10 - 50g / m2, and its corrosion resistance is much different from that of hot galvanized pipe. In order to ensure the quality of regular galvanized pipe manufacturers, most of them do not use electric galvanizing ( cold plating ). Only those small enterprises with small scale and outdated equipment adopt electro - galvanizing, and of course their prices are relatively cheap. The Ministry of Construction has officially eliminated cold galvanized pipes that are backward in technology. Cold galvanized pipes are not allowed to be used as water and gas pipes. The galvanized layer of the cold galvanized steel pipe is an electroplating layer, and the zinc layer is separated from the steel pipe matrix. The zinc layer is relatively thin, and the zinc layer simply adheres to the steel pipe matrix and easily falls off. Therefore, its corrosion resistance is poor. Cold galvanized steel pipes are not allowed to be used as water supply pipes in new residential buildings.
Weight factor
Nominal wall thickness ( mm ): 2.0, 2.5, 2.8, 3.2, 3.5, 3.8, 4.0, 4.5.
Coefficient parameters ( c ): 1.064, 1.051, 1.045, 1.040, 1.036, 1.034, 1.032, 1.028.
Note: The mechanical property of steel is an important index to ensure the final performance ( mechanical property ) of steel, which depends on the chemical composition and heat treatment system of steel. In the steel pipe standard, tensile properties ( tensile strength, yield strength or yield point, elongation ) as well as hardness and toughness indexes, as well as high and low temperature properties required by users are specified according to different use requirements.
Steel grade: Q215A; Q215B； Q235A； Q235B。
The test pressure value / MPa: d 10.2 - 168.3 mm is 3 MPa; D 177.8 - 323.9 mm is 5 MPa
Current national standard
National Standard and Dimension Standard for Galvanized Pipes
GB / T 3091 - 2015 Welded Steel Pipe for Low Pressure Fluid Transportation
GB / T 13793 - 2008 Straight Seam Welded Steel Pipe
GB / T 21835 - 2008 Welded Steel Pipe Size and Weight Per Unit Length
It is often said that galvanized pipes are used for gas and heating. galvanized pipes are also galvanized pipes. after several years of use, a large amount of rust and dirt will be produced in the pipes. the yellow water not only pollutes the sanitary ware, but also is mixed with bacteria that breed on the unsmooth inner walls. corrosion causes the heavy metal content in the water to be too high, seriously endangering human health.
Production steps
A, round steel preparation;
B heating;
C hot rolling perforation;
D cutting the head;
E pickling;
F, grinding;
G lubrication;
H cold rolling;
I degreasing;
J solution heat treatment;
K straightening;
L, cutting pipe;
M, pickling;
N, finished product inspection.
Technical requirements
1, brand and chemical composition
The grade and chemical composition of steel for galvanized steel pipes shall conform to the grade and chemical composition of steel for black pipes specified in GB / T 3092.
2. Manufacturing method
The manufacturing method of black tube ( furnace welding or electric welding ) is selected by the manufacturer. Hot dip galvanizing is adopted for galvanizing.