Duct production

Author:Jason Peng
Cleanroom Engineering Technology Manager of Deiiang Company.

Product R&D Manager of GDC Inc. Cleanroom Equipment Manufacturing Company.

Executive Director of Guangdong Cleanroom Industry Association of China.

Engaged in R&D of related products for 15 years, with rich relevant technical experience
2024-11-28 | Visits:

VENTILATION DUCT SYSTEMS

Quality Inspection and Acceptance standards for Processing and Manufacturing

Introduction

This specification applies to the inspection and acceptance of the processing and manufacturing quality of metal ducts, non-metal ducts and composite ducts used in ventilation and air conditioning projects of construction projects.

Note: The processing and manufacturing quality of metal ducts and non-metal ducts used in ventilation and air conditioning projects of industrial and civil buildings shall comply with the provisions of this chapter, and the quality inspection and acceptance shall be carried out in accordance with the corresponding provisions.

Inspection Principles

Acceptance Criteria

The acceptance of the manufacturing quality of ducts shall be carried out according to:

Different materials
System categories
Places of use

Main considerations include material, specifications, strength, tightness and appearance quality.

Design Compliance

Acceptance must be carried out according to design drawings and specification provisions. Purchased ducts must provide:

Product qualification certificates
Strength verification
Tightness verification

Note: The basis for duct acceptance is the provisions and design requirements of this specification. When design requires higher quality standards, construction should follow these higher standards.

Duct Specifications

For acceptance of ventilation duct specifications:

Ducts shall be based on outer diameter or outer side length
Building ducts based on inner diameter or inner side length
Basic series should be used first for round ducts
Irregular oval ducts refer to rectangular ducts

Round Duct Diameters (mm)
Basic Series	Auxiliary Series	Basic Series	Auxiliary Series
100	80	250	240
90	-	280	260
120	110	320	300
140	130	360	340
...	...	...	...

The basic series should be used for general supply, exhaust and Air conditioning systems. Ducts of dust removal and pneumatic conveying systems have high flow rates where pipe diameter greatly impacts resistance loss - the auxiliary series can be used in these cases.

System Classification by Pressure

The air duct system is divided into three categories according to the working pressure of the system:

System Category	System Working Pressure (Pa)	Sealing Requirements
Low Pressure System	P ≤ 500	Sealing of joints and pipe connections
Medium Pressure System	500 < P ≤ 1500	Additional sealing measures for joints and pipe connections
High Pressure System	P > 1500	Sealing measures for all joints and pipe connections

Air ducts in ventilation and air-conditioning engineering should be divided into three levels according to the nature of the system and the working pressure. This classification is based on current ventilation technology development needs and duct manufacturing technical levels.

Material & Construction Requirements

Material Connections

Galvanized steel plates and steel plates with composite protective layers:

Must be connected by bite joints or riveting
Welding connections that affect anti-corrosion performance are prohibited

The anti-corrosion performance depends on the protective layer. Welding can damage this layer and cause exponential corrosion increase at weld points.