Hot Dipped Galvanized vs Pre Galvanized Steel Pipe: Which One Should You Choose?

Quick Comparison Table

FeatureHot Dipped Galvanized (HDG)Pre Galvanized (Pre-Galv)
ProcessFinished pipe dipped in molten zinc bathSteel sheet/coil zinc-coated before pipe forming
Zinc Coating45–85 μm (300–600 g/m²)10–25 μm (80–180 g/m²)
Coating StandardASTM A53 / A123 / BS EN ISO 1461ASTM A653 / JIS G3302
Corrosion Life30–50 years (outdoor)15–25 years (sheltered)
Weld Seam ProtectionFull coverage (inside & out)Weld zone exposed — needs touch-up
Surface FinishMatte, spangled patternSmooth, bright, uniform
Max Pipe SizeUp to 12" (with large bath)Typically up to 6"
Cost (Relative)100% (baseline)70–85% of HDG
Best UseOutdoor, structural, water supplyIndoor, conduit, light framing
Zinc GradeZN-0 (99.995% pure zinc)Commercial zinc (99.5%+)

Manufacturing Process Differences

How Hot Dipped Galvanized Pipe Is Made

  1. Pipe Forming: Steel strip is rolled and welded into round pipe (ERW process).
  2. Surface Preparation: Degreasing → acid pickling → water rinsing → flux application.
  3. Hot Dip: Pipe is fully immersed in molten zinc at 840–860°F (450–460°C) for 30–90 seconds.
  4. Cooling & Inspection: Water quench cooling, zinc thickness measurement, visual inspection.
  5. Threading (Optional): Threads are cut after galvanizing for NPT/BSP connections.

How Pre Galvanized Pipe Is Made

  1. Coil Galvanizing: Cold-rolled steel coil passes through continuous hot-dip zinc pot at mill.
  2. Slitting: Galvanized coil is slit to required widths.
  3. Pipe Forming: Slit strip is roll-formed and ERW welded into pipe.
  4. Cut-to-Length: Pipe is cut to standard 5.8m or 6m lengths.
  5. End Finishing: Ends may be plain, grooved, or threaded.

Critical difference: In pre-galvanized pipe, the weld seam burns off the zinc coating during welding. This leaves a raw steel zone along the weld line that must be cold-galvanized (zinc-rich paint) for protection — but never matches the metallurgical bond of hot-dip.

When to Use Each Type

Choose Hot Dipped Galvanized Pipe When:

Choose Pre Galvanized Pipe When:

Cost Comparison (July 2026 Reference)

Pipe SizeHot Dipped (USD/Ton)Pre Galvanized (USD/Ton)Savings
1/2" (DN 15)$680–$750$520–$580~22%
1" (DN 25)$650–$720$500–$560~22%
2" (DN 50)$620–$690$490–$540~20%
3" (DN 80)$610–$680$480–$530~20%
4" (DN 100)$600–$670$470–$520~21%

FOB Tianjin China prices. Hot-dip zinc coating: 300 g/m² minimum. Quantity discounts from 25 tons. All prices subject to final confirmation.

Governing Standards

StandardApplies ToKey Requirement
ASTM A53HDG pipe (general)Zinc ≥ 300 g/m², uniform coating
ASTM A123HDG (fabricated products)Min coating by steel thickness
BS EN ISO 1461HDG (international)Coating thickness by steel thickness
ASTM A653Pre-galv sheet/coilZinc coating designation G30–G235
JIS G3302Pre-galv (Japanese/Asian)SGC400–SGC570 grades
BS 1387HDG water pipe (UK)Light/Medium/Heavy grades

Need Galvanized Steel Pipe? Contact Sino East Steel

We manufacture both hot dipped and pre galvanized steel pipes in our Tianjin factory. 6 production lines, 500,000 MT annual capacity. Custom cutting, threading, grooving, and end finishing available.