Types of Duct Joints and How to Choose the Right One

Types of Duct Joints

When installing ductwork for heating, ventilation, and air conditioning (HVAC) systems, various types of joints are used to connect duct sections together. The choice of duct joint depends on factors such as the type of duct material, system pressure, and air leakage requirements. Here are some common types of duct joints:

1. Snap Lock Joints

Snap lock joints are commonly used for sheet metal ductwork. They feature a male and female connection that interlock together, creating a secure and airtight seal. Snap lock joints are quick and easy to assemble, making them a popular choice for residential HVAC systems.

2. Slip Joints

Slip joints, also known as slip-fit or telescoping joints, involve inserting one end of a duct section into another to create a joint. This type of joint allows for easy adjustment and alignment during installation. Slip joints are often used in round or flexible ductwork.

3. Flanged Joints

Flanged joints consist of duct sections with raised flanges that are bolted or screwed together. Flanged joints provide a secure and durable connection, making them suitable for high-pressure HVAC systems. They are commonly used in commercial and industrial applications.

4. Butt Joints

Butt joints involve joining two duct sections by aligning their ends and securing them together. This type of joint is typically used with duct board or fiberglass ducts. Adhesives or specialized tapes may be used to provide additional sealing and reinforcement.

5. Corner Joints

Corner joints are used to connect duct sections at corners or angles. Depending on the type of duct material, corner joints can be created using various methods such as folding, bending, or welding. Properly executed corner joints ensure smooth airflow and minimize air leakage.

6. Flanged and Gasketed Joints

Flanged and gasketed joints combine the use of flanges and gaskets to create a secure and airtight connection. Flanges are bolted together, and a gasket is placed between them to provide a sealing barrier. This type of joint is often used in HVAC systems that require high sealing efficiency.

The selection of the appropriate type of duct joint depends on factors such as system pressure, duct material, installation requirements, and air leakage standards. It is important to follow industry best practices and manufacturer guidelines when installing duct joints to ensure proper sealing and optimal system performance. Consulting with a professional HVAC contractor or engineer is recommended for determining the most suitable duct joint type for your specific application.