How to inspect the quality of galvanized steel pipes?

There are two types of galvanization:hot-dip galvanizing (hot-dip zinc coating) and cold galvanizing (electro-galvanizing). Hot-dip galvanizing produces a thick zinc layer with uniform coating, strong adhesion, and long service life. In contrast, electro-galvanizing has lower cost, but the surface is not very smooth, and its corrosion resistance is much poorer than that of hot-dip galvanized pipes. So, how should we inspect the quality of galvanized pipes?

1.Wall Thickness Inspection

The main tool used for wall thickness inspection is the micrometer. During inspection, use the micrometer to measure the wall thickness of each galvanized square pipe one by one. Before inspection, first verify that the micrometer's calibration certificate is within the validity period, and check that the micrometer is set to zero, rotates smoothly, and that the measuring faces are free of scratches and rust spots. It can only be used after passing these checks.

2.Outer Diameter and Ovality Inspection

The main tools used for outer diameter and ovality inspection are plug gauges and vernier calipers. During inspection, use a qualified plug gauge to measure the outer diameter of each galvanized square pipe one by one. Before inspection, first verify that the plug gauge's calibration certificate is within the validity period, and use a vernier caliper to check the plug gauge being used, ensuring that the measuring faces are free of scratches and rust spots. It can only be used after passing these checks.


3.Length Inspection

The main tool used for length inspection of galvanized square pipes is a steel tape measure. When measuring the length, align the ' 0 ' mark of the tape measure with one end of the pipe, then pull the tape taut so that the scale side of the tape is pressed against the surface of the pipe. The reading at the other end of the pipe is the length of that galvanized square pipe.


4.Straightness (Bending) Inspection of Galvanized Square Pipes

The straightness inspection of galvanized square pipes mainly checks the overall length bending and the bending per meter. The main tools used are spirit levels, feeler gauges, and fishing line (monofilament line).http://www.hnftsteels.com