Weicon WEICONLOCK AN 302-25 Anaerobic Thread Sealant

Weicon WEICONLOCK AN 302-25 is an anaerobic thread sealant designed to provide leak-tightness in metal threaded connections and help reduce loosening caused by vibration. Thanks to its brown, high-viscosity formulation, it is especially suitable for controlled application on coarse threads. It cures in the oxygen-free zone where metal surfaces are in contact, forming a thin sealing film inside the joint. As it is positioned in the low-strength range, it is preferred for applications where easier disassembly during service and maintenance is desired.

Thread and flange sealing with WEICONLOCK AN 302-25

AN 302-25 is a single-component, anaerobically curing industrial adhesive/sealant compound that aims to fill gaps in threaded joints and block micro-leakage paths. While it helps against loosening under vibration on coarse threads, it is better suited for maintenance scenarios where full “locking” of the connection is not desired. Its high viscosity helps it stay on the thread crests without running, contributing to reduced product waste. The manufacturer is WEICON GmbH & Co. KG, and the product is of German origin.

Technical performance and strength values of AN 302-25

The product is specified for use on threaded connections up to M80 / R3” and has a maximum gap-filling capacity of 0.3 mm. With a viscosity range of 6,000–30,000 mPa·s at +25 °C, it offers an application behavior that is more resistant to dripping, especially on large-diameter/coarse threads. In line with the aim of removability, the breakaway torque is defined as 5–8 Nm and the prevailing torque as 2–4 Nm. The shear strength is specified as 3–5 N/mm² according to DIN 54452; these values support the bonding/sealing function while providing serviceable retention rather than excessive locking.

Curing behavior and temperature resistance

Because the anaerobic system cures in the oxygen-free zone between metal surfaces, surface preparation and assembly speed directly affect performance. Reaching handling strength within 15–30 minutes helps keep waiting times manageable in routine maintenance work. Full strength is typically achieved within 3–6 hours; therefore, adequate curing time should be planned before applying pressure or putting the joint into service. The temperature resistance is stated as -60 °C to +150 °C, providing a suitable thermal window for many industrial fluid lines and machine-environment conditions.

Typical pressure resistance in pressurized applications and installation tips

The manufacturer shares compressive strength (pressure) values for certain sizes in free-cutting steel test fittings; for example, 1500 bar for M3x6–M5x8 joints, 1000 bar for M6x10, 800 bar for M8x12, and 400 bar for M10x16. In practice, surfaces should first be cleaned, the product should be applied evenly around the thread, and the connection should be tightened quickly to the desired position. For flange sealing, apply a continuous bead to one surface and assemble the parts without delay. The product should not be poured back into the bottle after contacting metal; in high-volume applications, using a dosing tip and, when necessary, an activator can help stabilize anaerobic industrial adhesive performance.

Sector-based applications and compatible surfaces

AN 302-25 can be used in hydraulic and pneumatic lines with metal pipes and fittings, pump/compressor connections, and maintenance operations for gearboxes and machine equipment. It is a practical solution for facility maintenance teams needing sealing in threaded connections that carry water, compressed air, and many industrial fluids. It is compatible with coarse-threaded metal joints in automotive supply, machinery manufacturing, process industries, agricultural machinery, and general MRO (maintenance, repair, and operations). Ease of disassembly during service, controlled application thanks to high viscosity, and the vibration-supporting effect of anaerobic curing are among the key advantages of this industrial adhesive/sealant solution.