First, the process of galvanized pipe
The production of galvanized pipe mainly consists of base pipe manufacturing (welded/seamless) → galvanized treatment of two major stages, the specific process is as follows:
1. Base pipe manufacturing (pipe molding)
(1) welded steel pipe (Welded Pipe)
Raw materials: hot-rolled or cold-rolled steel coils (SPHC, Q195-Q235, etc.).
Process flow:Steel strip uncoiling → leveling → high-frequency welding (HFW) / submerged arc welding (SAW) → removal of internal and external welding scars → sizing → cutting → inspection
Common types: straight seam welded pipe (ERW), spiral welded pipe (SSAW).
(2) Seamless Pipe
Raw material: round billet (carbon steel, alloy steel).
Process flow:Billet heating → punching → hot rolling/cold drawing → straightening → cutting → pickling → inspection
2. Galvanizing
The main types of galvanizing are hot dip galvanizing (HDG) and electro galvanizing (EG), of which hot dip galvanizing is more common:
(1) Hot-Dip Galvanizing (HDG)
Process:Degreasing by alkali washing → washing → descaling by acid washing → washing → auxiliary plating agent → drying → zinc dipping (molten zinc at 450°C) → cooling → passivation (optional) → inspection
Plating characteristics: thick zinc layer (50-200μm), strong corrosion resistance, suitable for outdoor use.
(2) Electro-Galvanizing (EG)
Process flow:
Electrolytic degreasing → acid washing → zinc plating (zinc salt solution electrified) → passivation → drying
Plating characteristics: thin zinc layer (5-30μm), smooth surface, suitable for precision parts or subsequent coating.