Seams & Joints
Pittsburgh seam, snap lock, grooved seam, standing seam, drive slip, S-slip, lap seam, and cleated seam.
- Describe the Pittsburgh lock seam and its application
- Explain the purpose and assembly of drive slips and S-slips
- Identify the recommended overlap for lap seams
- Describe the function of cleated seams in sheet metal roofing
- Differentiate between longitudinal and transverse duct connections
Leçon 1
Longitudinal Seams
Pittsburgh Lock Seam
The purpose of a Pittsburgh lock seam is to create a strong, airtight longitudinal joint for rectangular ductwork. The Pittsburgh seam interlocks two edges of sheet metal without soldering or fasteners. One edge has a pocket (Pittsburgh pocket) and the other has a single lock that slides into the pocket and is hammered flat.
Snap Lock Seam
A snap lock seam (also called a snap-lock Pittsburgh) is similar to the Pittsburgh but designed to snap together without tools at the job site. Snap locks are used where field assembly speed is important.
Grooved Seam
A grooved seam (also called a locked seam or round duct lock) is used for round ductwork. The type of seam most commonly used for round ductwork is the grooved seam. Both edges are turned in the same direction and locked together using a hand groover or groover machine.
Seam Direction
Longitudinal seams run along the length of the duct section. They close the sheet into a tube shape. The Pittsburgh seam is the standard longitudinal seam for rectangular duct.
The Pittsburgh lock seam is the standard longitudinal joint for rectangular duct - pocket-and-lock design closed with a hand groover. The grooved seam is standard for round duct. Both create airtight joints without soldering.