Standard Frames

Frames make up the metallic portion of a non-metallic expansion joint. There is a virtually endless list of frame configurations to choose from. Some of the most popular styles are shown below. PAPCO can configure frames to best match your application in either “Bolt-to-Duct” or “Weld-to-Duct” variations.

Angle Frame

Angle Frames are an economical solution to many expansion joint applications. Angle Frames can be of the “In-Line” or “Stand Off” variety. They can be made from standard structural angle or fabricated from plate. Depending on the application, they may be used with or without baffle liners.

Low Profile Angle Frame

Angle Frames are an economical choice and are fabricated from standard Structural Profiles or are custom bent and/or rolled to suit. Low-Profile Angle Frames are also favored since they can be shipped fully assembled which reduces field labor costs. They may be supplied with or without baffles.


Z-Frames are one of the most popular, robust, and easy to install frame styles. Z-Frames include dual-overlapping baffle liners which are an integral part of the frame. No additional welding is required for installation of the baffle liners. Z-Frames are ideally suited for both high temperature and heavy particulate flow medias. Z-Frames can also be easily fitted with a fully installed fly ash seal for extreme applications. The baffles on Z-Frames will not extend beyond the downstream frame. Z-Frames can be welded to the duct mounting flanges or supplied with seal welded nuts for “bolt-in” installation.


J-Frames include integral outboard flanges which allow them to slide easily in between two mounting flanges without any need to pre-compress the joint or jack open the breech. Additionally, a J-Frame may include either double overlapping or single sided baffle liners. They can be integral to the frame or field welded at the time of installation. J-Frames can also be easily fitted with a PAPCO style “Fully Installed” fly ash seal.

Channel Frames

Channel Frames are fabricated with standard C/MC Structural Channel and may include either integral (factory) installed or loose (field welded) baffle liners. Channel Frames may provide additional support and structural rigidity to the duct opening.

Fabric-Over-Metal Frames

This configuration allows you to retrofit existing, leaking metallic bellows. Frames of this style enable you to wrap a fabric belt over the top of an existing metal bellow without having to remove the old metal joint. Fabric-over-metal type frames can be combined with insulation pillows and/or baffle liners for maximum durability.