External diameter(mm)

7.8±0.08

4.76±0.08

4±0.05

Thickness（mm）

0.6+0.03-0.02

0.6+0.03-0.02

0.5±0.03

Appearance

It shall be clean, smooth, free of scars, zinc particles, peeling, rust and corrosion spots, and the height of inner weld shall be ≤ 0.2mm (for wall thickness ≤ 0.5mm, the height of inner weld shall be ≤ 0.15mm)

Flatten Test

After flattening, the outer edge of the steel pipe shall be free of cracks, cracks or weld cracks

Flaring Test

Use ￠ 8.4 punch

Use ￠ 5.2 punch

Use ￠ 3.75 punch

The reaming shall be free of cracks, cracks or weld cracks. The pipe orifice at the reaming end shall be flush and the pipe shall be smooth and flat;

扭曲试验Twisting Test

Insert the mandrel at both ends, and the twist angle is 3 * 360 ° on the left and right respectively. After the test, the steel pipe shall be free of wrinkles, cracks or other cracks

Bending Test

The bending core with a radius of 3 times the diameter of the steel pipe shall be used, and there shall be no wrinkles, cracks or other cracks after bending; The roundness (diameter difference) of the pipe section at the bend shall not be greater than 0.8

Outer coating

4-15 μ m. Coating adhesion: it is required to be dense and firmly bonded with the substrate

Salt

 Spray Test

No red rust in 48 hours

Internal

Cleaness

≤20mg/m²

Moisture

≤20mg/m²

Single

 Impurity

≤0.2mm

Tolerance

No turbidity, stratification and cloud

ROHS Test

Cd and compounds

＜50

pb and compounds

＜500

Hg and compounds

＜500

Cr6＋compounds

＜500