Introduction to Seal Strips for Plate-Fin Heat Exchangers

1. Function and Processing of Seal Strips

In each layer of the flow passage of a plate-fin heat exchanger, seal strips are installed on both sides. These seal strips come in various structural forms. Based on their cross-sectional shape, common types include Type A, Type B, Type C, and Type D seal strips, which are manufactured from aluminum profiles. Typically, upon procurement from specialized suppliers, they are cut to the required design length using a sawing machine or a dedicated seal strip cutting machine, followed by deburring, straightening, and cleaning before use.

2. Requirements for Seal Strips

(1) The seal strip material shall be 3003-H112 aluminum alloy, meeting the chemical composition requirements specified in GB/T 3190 "Wrought Aluminum and Aluminum Alloys – Chemical Composition" for 3A21 aluminum alloy. Chemical analysis shall be conducted in accordance with GB/T 6897 "Methods for Chemical Analysis of Aluminum and Aluminum Alloys."

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(2) The surface of the profile shall be smooth and flat, free from cracks, wrinkles, corrosion spots, and nitrate stains. Slight oxidation discoloration and dark spots are permissible.

(3) The end faces of the seal strip shall be cut flat, with an angular deviation from the perpendicular not exceeding 3°. Burrs at the cut ends shall be removed.

(4) The upper and lower surfaces shall not have pits, indentations, bubbles, or scratches that exceed the specified negative tolerance.

(5) The upper and lower surfaces must remain straight. The degree of bending over a length of 1 meter shall not exceed 0.5 mm, and sharp kinks are not permitted.

(6) The degree of twist over a length of 1 meter shall not exceed 0.1 mm.