Production technology of galvanized steel pipe
Black inspection → hanging → degreasing → rinse → pickling → cleaning → dipping help plating → hot air drying → hot dip galvanizing → cooling → passivation and rinsing → discharge → inspection and dressing → packaging storage and transport
Technical requirements galvanized pipe should meet
1. Shop sign and chemical composition
The shop sign and chemical composition used by galvanized steel pipe should be consistent with those of black steel pipe stipulated by GB 3092.
2. Manufacturing method
The manufacturing method of the black tube (furnace welding or welding) is selected by the manufacturer. Galvanized steel pipe adopts hot dip galvanizing method.
3. Thread and pipe joint
(1) The galvanized steel pipe with thread to delivery, the thread should be vehicle-made after galvanized. The thread should be in accordance with YB 822.
(2) The steel pipe joints should be consistent with the provisions of YB 238, malleable iron pipe joints should be consistent with the provisions of YB 230.
4. Mechanical properties
Mechanical properties of steel pipe before galvanized should be consistent with the provisions of GB 3092.
5. Galvanized layer uniformity
Galvanized steel pipe should be carried out galvanized layer uniformity test. Steel pipe samples can not be red (copper) in the copper sulfate solution for 5 times.
6. Cold bending test
The galvanized steel pipe that nominal diameter is not more than 50mm should be carried out cold bending test. The bending angle is 90 ° and the bending radius is 8 times the outer diameter. Test without the filler, the sample weld should be placed in the bending direction of the outside or the upper part. After the test, there should be no cracks and cracks on the sample.
7. Hydraulic pressure test
Hydraulic pressure test should be carried out in the black tube, eddy current can also be used instead of hydraulic test. Test pressure or eddy current testing Contrast sample size should be in accordance with GB 3092.
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