Henkel LOCTITE 573 Slow Cure Flange Sealant for Rigid Metal Flanges

LOCTITE 573 Slow Cure Flange Sealant for Large Assemblies

Unlike pre-cut gaskets, this form-in-place material conforms to the actual flange geometry and fills microscopic surface irregularities between correctly prepared mating faces. It cures when confined between close-fitting metal surfaces in the absence of air, creating a medium-strength seal that helps prevent leakage while supporting later service disassembly with appropriate tools. The one-part formula requires no weighing or mixing, helping reduce preparation time, ratio errors, and unused mixed material.

LOCTITE 573 Slow Cure Flange Sealant is formulated for steel and aluminum flanges and is well suited to applications where assembly may take several hours. Henkel lists a fixture time of approximately nine to twelve hours, which supports deliberate positioning of large covers and housings. The product is designed for close-fitting flange gaps and may be used on validated gaps up to 0.25 mm, depending on the application method and process conditions.

Industrial and Automotive Flange Applications

Typical uses include gearbox casings, engine housings, pump covers, transmission assemblies, compressors, bearing housings, industrial machinery, and other machined rigid flanges. The cured material provides resistance to common automotive and industrial fluids. Henkel testing reports retained strength after exposure to motor oil, gasoline, and water-glycol mixtures under specified laboratory conditions, although every production assembly should be tested with its actual fluids, temperatures, pressures, and service cycles.

7 Benefits of LOCTITE 573 Slow Cure Flange Sealant

• Extended assembly time: Suitable for large flange jobs that require careful positioning.
• One-component processing: Eliminates resin-and-hardener mixing before application.
• Thixotropic consistency: Helps reduce dripping and migration on flange surfaces.
• Form-in-place sealing: Conforms to flange geometry and surface irregularities.
• Fluid resistance: Supports automotive and industrial equipment applications.
• UV fluorescence: Allows easier visual confirmation during process inspection.
• Medium-strength cure: Provides reliable sealing while supporting planned maintenance.

Application and Curing Guidance

Remove old gasket material and clean both flange surfaces until they are dry and free from grease, oil, dust, moisture, and loose contamination. Apply the product as a continuous bead, rolled film, or screen-printed layer to one flange. For wider gaps using a roller process, Henkel recommends applying a rolled film to both mating surfaces. Assemble the components and tighten the flange promptly to avoid unwanted shimming.

Low-pressure testing below 0.5 MPa may be performed immediately after assembly to confirm a complete seal before full cure. If curing is too slow because of low temperature, passive metal, or a larger gap, compatible LOCTITE SF 7471 or SF 7649 Activator may improve cure speed after validation. The product is not normally recommended for thermoplastics and should not be used in pure oxygen, oxygen-rich systems, chlorine, or strong oxidizing environments.

Official Resources and Related Gasketing Products

Review the official Henkel LOCTITE 573 product page and the official LOCTITE 573 technical data sheet for current specifications, application instructions, storage guidance, and safety documentation.

Explore our anaerobic flange sealants for additional rigid metal gasketing solutions. You can also browse our industrial gasket sealants for engines, gearboxes, pumps, and machinery. Store unopened containers in a dry location, ideally between 8°C and 21°C. Contact our sales team for quotations, package availability, bulk orders, technical documents, and export support.