Generally , three different seams are common in the industry to connect the corners of the ducts : button lock seam , pittsburgh seam and duct seam . Button snap lock and pittsburgh lock can be produced on the Comifo lock forming mahicnes . The pittsburgh seam shows much better results and can also be used for a higher pressure.

Vertical duct seam closer is what we highly recommed . Pittsburgh joint is commonly used to join the seams of metal ducts . Seam closing has traditionally been accomplished by manually hammering the margin of the seam against the duct wall ( penning ) . Disadvantages of such peening inclufe the time required and the almost intolerable noise produced . 

The latest desigh in seaming technology is  now available . At the pittsburgh joint . the individual seams are called pittsburgh seam ( pittsburgh lock ) and standing seam ( right angle lock ) . On a pittsburgh joint , the operator pushes the standing seam into the pittsburgh seam , fastens them to each other and closes the joint on a seam mahcine .