Technical Requirement of Galvanized Steel Pipe
1, grades and chemical composition
Galvanized steel grades and chemical composition should be consistent with GB 3091 under the black tube steel grades and chemical composition.
2, the manufacturing method
The manufacturing method of the black tube (furnace welding or welding) is selected by the manufacturer. Galvanized by hot-dip galvanizing method.
3, thread and pipe joints
3.1 galvanized steel pipe with threaded delivery, the thread should be in galvanized after the car system. Threads shall comply with YB 822.
3.2 steel pipe joints should be consistent with the provisions of YB 238; malleable iron pipe fittings should be consistent with YB 230 requirements.
4, mechanical properties of galvanized steel pipe before the mechanical properties should be consistent with the provisions of GB 3091.
5, uniformity of galvanized galvanized steel pipe galvanized layer should be uniformity of the test. Steel pipe samples in copper sulfate solution for 5 consecutive impregnation shall not be red (copper color).
6, cold bending test Nominal diameter of not more than 50mm galvanized steel pipe should be cold bending test. Bending angle of 90 °, bending radius of 8 times the diameter. Test with no filler, the specimen weld should be placed in the bending direction of the outer or upper. After the test, the sample should not have cracks and zinc peeling off the same.
7, water pressure test Water pressure test should be carried out in the black, eddy current testing can also be used instead of water pressure test. Test pressure or eddy current inspection shall be in accordance with GB 3092 for the size of the reference sample.