Galvanized Steel Pipe
In order to improve the corrosion resistance of the steel pipe, in general people will coated the steel pipe with zinc. Galvanized steel pipe is mainly used for transporting gas and heating.
If use galvanized steel pipe as water pipes for drinkable water, after many years of application, it turns out there are many rust inside the steel pipe which will influence the quality of the
drinking water.
Galvanized Steel Pipe Weight Formula: ( Outside Diameter - Wall Thickness) x Wall Thickness x 0.02466 * 1.0599 = Weight per Meter (kg / m)
There are two types of galvanized steel pipe in the market which is divided by the production processes.
Hot-dipped zinc coating is the molten metal to react with the iron matrix alloy layer. So the substrate and the zinc coating combined well. The first production step is pickling the steel pipe.
In order to remove the surface of the iron oxide, cleaning bath by mixing an aqueous solution of ammonium chloride or zinc chloride aqueous solution for the after pickling steel pipe is
needed. And then the steel pipe is allowed to put in the hot dip tank. The using advantage for hot dipped galvanized steel pipe is the coating has strong adhesion and long using life.
Applying hot-dipped galvanizing process, the zinc coating will be combined with the surface of the steel pipe evenly.
Production Process:
Material Inspection (Steel Pipe) --- Hanging --- De-greasing --- Rinsing --- Pickling --- Washing --- Dipping Fluxing --- Hot Air Drying --- Inside and Outside Hot-dipped Galvanizing Blow
--- Cooling --- Passivation and Rising --- Unloading --- Inspection and Trimming --- Type Identification --- Packaging and Storing and Transportation.
Cold Galvanized Steel Pipe:
Cold Galvanizing process is also named as electro-galvanizing process which is using cold plates as raw material. Cold Galvanized Steel Pipe has very few zinc coating which is only around
10 ~ 50 g/m2. Compared with hot-dipped galvanized steel pipe, the corrosion resistance of cold galvanized steel pipe is not as good as hot-dipped galvanized steel pipe.
In order to ensure the quality of the galvanized steel pipe, most of the galvanized steel pipe manufacturers will not apply the electro galvanizing producing process. Only those small and
outdated manufacturers still use electro-galvanizing producing process to offer relatively cheaper galvanized steel pipe. Since the zinc layer for cold galvanized steel pipe is electroplated layer,
it is the individual layered zinc coating on the steel pipe, so the coating layer will be peel off easily. Overall, the producing cost for cold galvanized steel pipe is lower than hot-dipped
galvanized steel pipe, and the manufacturer can offer the purchaser a very competitive market price. However, the surface of the coating is uneven which influence the corrosion resistance
of the galvanized steel pipe.
Production Process:
Uncoiling (Galvanized Steel Strips/Plates) --- Leveling --- Welding --- Scraping the Scar --- Passivation and Rinsing --- Zinc adding --- Setting/Forming --- Type Identification --- Cutting
--- Packing --- Drying --- Weighed
