Often said galvanized pipe, galvanized pipe use now gas, heating of the type of iron pipe is also galvanized pipe, galvanized pipe as a pipe, after a few years, the use of a large number of rust in the pipe, the effluent of the yellow water pollution not only sanitary ware, but also mixed with the smooth inner wall of the bacteria, corrosion caused heavy heavy metal content in the water, serious Harm the health of the human body. In 60s and 70s, the developed countries began to develop new types of pipes and banned galvanized pipes one after another. The four ministries and commissions, such as the Ministry of construction of China, also make sure that the galvanized pipes have been banned from the two 000 years. At present, galvanized pipes have been rarely used in the cold water pipes of the newly built communities, and some hot water pipes in some communities use galvanized pipes.
Inspection of black parts, material, skimming, rinsing, pickling, cleaning, cleaning, dipping and helping plating, hot air drying, hot dip galvanizing, cooling, passivation and rinsing, unloading, unloading, inspection, dressing, packing and transportation, transportation and transportation
Can only provide a general process, more details belong to the manufacturer's secret.
Technical requirements for galvanized pipes
1, brand and chemical composition
The grades and chemical composition of the steel for galvanized steel pipe shall conform to the grade and chemical composition of the steel used for GB 3092.
2, manufacturing method
The manufacturing method of the Clarinet (furnace welding or electric welding) is chosen by the manufacturer. Galvanizing by hot dip galvanizing.
3, thread and pipe joint
3.1 the galvanized steel pipe with thread delivery shall be made after galvanizing. The thread shall be in accordance with the provisions of YB 822.
3.2 the steel pipe fittings shall conform to the requirements of YB 238, and the malleable iron pipe joints shall conform to the requirements of YB 230.
4. Mechanical properties of steel pipes before galvanizing should meet the requirements of GB 3092.
5. Uniformity of galvanized coating. Galvanized steel pipe should be tested for uniformity of zinc coating. The steel tube specimens are impregnated continuously in copper sulphate solution for 5 times and shall not be reddish (copper plated).
6. The cold bending test of the galvanized steel pipe whose nominal diameter is less than 50mm should be subjected to cold bending test. The bending angle is 90 degrees, and the bending radius is 8 times of the outer diameter. Without filling in the test, the specimen weld
It should be placed on the outside or upper part of the bending direction. After test, there should be no cracks and zinc coating peeling off.
7. Hydraulic pressure test should be carried out in the black pipe or eddy current test instead of water pressure test. The size of the test pressure or eddy current flaw detection shall conform to the requirements of GB 3092.
Mechanical properties of steel is an important index to ensure the ultimate performance of steel, which depends on the chemical composition of steel and heat treatment system. In the standard of steel pipe, the tensile properties (tensile strength, yield strength or yield point, elongation), hardness and toughness index, and high and low temperature properties required by the user are stipulated in the standard of steel pipe.
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