GB/T6728-2002   ASTM A500 Gr. A.B.C.   JIS G3466

Different appearance of the surface:

BRIGHTEN: Brighten steel pipe is made of brighten annealed steel strip (a kind of material corresponding to CR). Similar with black tube made of cold rolled coil, brighten steel pipe keeps the original brighten color of steel.

PRE-GALVANIZED: Pre-galvanized tube is made of hot dipped galvanized steel strip directly.

HOT DIPPED GALVANIZED : Hot dipped galvanized tube owns thicker zinc coating than pre-galvanized tube. Black tubes will be dipped into zinc pool for galvanizing.

ELECTRO-GALVANIZED: The technology of electro-galvanized tube is similar to hot dipped galvanized tube, but the thickness of zinc coating is less than hot dipped galvanized tube.

The dissimilarity of workmanship among hot dipped galvanized tube, per-galvanized tube and electro-galvanized tube results in different level of erosion resistance and cost.

The performance of hot dipped galvanized tube is the best, then pre-galvanized tube, and last electro-galvanized tube.