Cold cutting saw cold bending test galvanized steel tube with nominal diameter not greater than 50mm shall be cold bending test.

The bending Angle is 90° and the bending radius is 8 times of the outer diameter. No filler shall be used during the test. The weld of the sample shall be placed on the outside or upper part of the bending direction. After the test, there should be no cracks and spalling of zinc layer on the sample. Hydrostatic test the hydrostatic test shall be carried out in the clarinet or eddy current testing may be used instead of hydrostatic test. The size of test pressure or eddy current test specimen shall conform to GB 3092. The mechanical property of steel is an important index to guarantee the final use property of steel. The zinc of cold cut saw galvanized steel tube is in airtight or ventilated bad, air moist condition, and nonmetallic material volatile matter (low molecular carboxylic acid, aldehyde, phenol, ammonia, etc.) contact, zinc is easy to be corroded, the formation of white loose corrosion products, commonly known as "frost".

 Zinc in high temperature, high humidity, sealed conditions, and bakelite, paint, wood release volatile contact, zinc has the tendency to grow fine filament single crystal, commonly known as "long hair".