Round galvanized steel spiral duct with continuous helical lock seam

Cleanroom Air Distribution Systems

Spiral Galvanized Steel Duct

A round galvanized steel duct formed with a continuous spiral lock seam for rigid, aerodynamically efficient cleanroom supply and return routes.

Continuous Spiral Lock Seam
Rigid Round Geometry
Low-Friction Air Path
Gasketed Fitting System

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Product Introduction

Spiral duct is manufactured by helically forming galvanized strip into a rigid round tube with a continuous locked seam. The circular cross-section resists pressure deformation efficiently and usually requires less reinforcement than a broad rectangular panel. Factory-made elbows, branches and reducers use male insertion ends with double-lip gaskets or sealed slip joints. Exposed installations benefit from the regular spiral appearance, while concealed cleanroom services gain a compact duct with predictable support and airflow characteristics.

Key Features

The helical lock seam stiffens the duct wall along its full length without separate external bracing.

A circular bore distributes internal pressure uniformly and supports smooth airflow through long runs.

Double-lip gasketed fittings shorten assembly time and create repeatable insertion joints.

Standard round accessories simplify changes in diameter, direction and branch layout.

Customer Product Concerns

Round duct routes must balance ceiling-space use, joint leakage, hanger spacing and clean fitting transitions at every branch.

Thin round duct ovalizes during transport or hanging.Spiral seam stiffness and correctly spaced circular supports retain the designed diameter.

Field-applied sealant is inconsistent around every fitting.Factory-fitted double-lip gaskets provide uniform circumferential sealing at insertion joints.

Abrupt branch fittings create turbulence and excess pressure loss.Swept bends and gradual conical transitions preserve the round flow path.

Condensation forms on exposed cold supply duct.A continuous external vapor-sealed insulation system is added for the scheduled air temperature and humidity.

Typical Applications

Cleanroom supply-air branchesExposed technical-space ductworkReturn-air systemsLaboratory general exhaustAir-handling equipment connections

Technical Parameters

Typical manufacturing ranges for galvanized spiral duct used in HVAC air distribution are listed below.

Core Material	Hot-dip galvanized carbon-steel strip
Panel Thickness	0.45–0.90 mm spiral-formed wall
Effective Width	80–1250 mm nominal internal diameter
Maximum Length	3000–6000 mm standard straight length
Steel Facing Thickness	0.45–0.90 mm galvanized steel wall
Core Density	Approximately 7850 kg/m³ solid steel construction
Thermal Conductivity	Approximately 48–54 W/(m·K) for spiral-forming galvanized strip
Surface Finish	Bright galvanized surface with optional external powder coating
Joint Type	Gasketed male-female slip joint secured with screws or sealed rivets
Customization	Available based on the intended application and operating environment.

Available Options

Galvanized, aluminum or stainless constructionFactory-applied external insulationPowder-coated exposed finishGasketed elbows, tees and reducers

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