What is the allowance for a Pittsburgh seam formed in a roll former?

In a roll former, the allowance for creating a Pittsburgh seam is typically 1 inch. The Pittsburgh seam consists of two pieces of sheet metal that are folded and crimped together, which provides a secure and airtight seal, crucial for sheet metal ductwork in HVAC systems.

Using an allowance of 1 inch ensures that there is enough material to properly execute the fold and crimp, allowing for a well-formed seam that can withstand the pressures and temperatures it will encounter in HVAC applications. This dimension is standard in the industry to ensure compatibility and functionality across systems and components, enhancing the durability and performance of the entire installation.

Other measurements, while they might appear in different contexts or applications, do not account for the necessary structural integrity and airtight requirements that an effective Pittsburgh seam needs.