Profile: Omni Duct Systems specializes in HVAC round, rectangular and oval duct jobs. Our product line includes spiral pipe, round fittings, grease duct, aluminum flex duct and air distribution products. We provide spot-welded, seam-welded, solid welded, gore-locked and auto-locked seams. Our duct-seal is an adhesive compound that forms a durable, flexible, non-hardening membrane on air conditioning ducts.