Technical requirements for galvanized pipe

 

The grades and chemical composition of the steel used for galvanized steel pipe shall be in conformity with the grades and chemical composition of the steel used for GB/T3092.

 

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

 

(a) galvanized steel pipe with thread delivery. The thread should be made after galvanizing. The thread shall be in accordance with the provisions of YB 822.

 

(b) the steel pipe fittings shall conform to the requirements of YB 238, and the malleable cast iron pipe joints shall conform to the provisions 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. The test should not be filled with filler. The weld 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. The mechanical properties of steel are important indicators to ensure the ultimate use performance (mechanical properties) of steel.