WEICON WEICONLOCK® AN 305-78 Anaerobic Thread Sealant

WEICON WEICONLOCK® AN 305-78 Anaerobic Thread Sealant is a single-component product that cures anaerobically and is designed to seal metal pipe threads and flange surfaces. It hardens in the metal-to-metal contact zone where oxygen is excluded, forming a permanent sealing film along the joint line. Its high-viscosity consistency helps the material remain in place in the thread roots without flowing or spreading uncontrollably. The product is manufactured by WEICON GmbH & Co. KG, Germany.

Sealing Pipe and Threaded Connections with WEICONLOCK AN 305-78
AN 305-78 is a pipe and thread sealing solution developed to achieve reliable curing even on passive metals, and it is part of anaerobic systems that are considered in the industrial adhesive category for assembly work. With its medium-strength profile, it provides sealing in the connection while being positioned to allow disassembly with standard hand tools when maintenance is required. It is specified for use on threaded connections up to M80 / R 3″, offering practical application on large-diameter line components. The high viscosity supports continuity of the sealing line at installation points exposed to vibration, pressure fluctuations, and thermal expansion. In this way, it helps reduce leak risk while also contributing to connection security through an industrial adhesive approach.

Anaerobic Chemical Base and Performance of AN 305-78
The product functions as a methacrylate-based anaerobic adhesive/sealant compound and cures in the confined area between metal surfaces. This mechanism aims to form a more uniform film layer as an alternative to conventional sealing materials in threaded lines. On passive materials, the performance focus is on supporting curing and achieving homogeneous sealing along the connection. The medium-strength class offers a balanced use between assembly security and serviceability. Since it can also create a locking effect in the joint line in addition to sealing, it is preferred as an industrial adhesive in process and maintenance applications.

Resistance and Mechanical Values
The temperature resistance of AN 305-78 is specified as -60 °C to +150 °C, supporting use both in cold lines and around installations exposed to temperature changes. As viscosity is defined at 50,000–80,000 mPa·s, it helps provide flow control and stable filling, especially in larger thread profiles. The gap-bridging capacity is stated as a maximum of 0.5 mm, contributing to completing the sealing line by filling thread gaps within suitable tolerances. For threaded connections, the breakaway torque is specified as 11–16 Nm and the prevailing torque as 4–7 Nm; disassembly behavior in maintenance scenarios should be evaluated within this framework. The product’s fluorescent property can offer an advantage for application checks and visual inspection.

Application Method and Process Safety
For best results, it is recommended to degrease and clean the connecting parts; the cleaner the surface, the more stable the sealing quality achieved. The product is applied evenly around the thread using the dispensing tip, and it is advised not to let the dispensing tip come into direct contact with the metal. Pipe threads are tightened to the desired alignment; for flange sealing, a continuous bead is applied to one flange face and the parts are joined quickly. Product that has contacted metal should not be poured back into the bottle, as even very small metal particles can cause premature curing inside the packaging. Handling strength is stated as 25–50 minutes, and final strength is stated to develop within 4–8 hours; commissioning plans should be made accordingly.

Sector-Based Applications and Compliance Notes
The product is positioned with an approval approach for drinking water applications, together with DVGW approval and a BAM reference; it also includes a reference to “Hygiene Institute” guidelines within the scope of UBA KTW-BWGL. This provides a suitable framework for installations with sealing requirements such as drinking water lines, building services, HVAC connections, and process piping. In pump, valve, filter, and measuring equipment connections, anaerobic sealing in the industrial adhesive category can be preferred to reduce leak risk and stabilize the joint line. In shipyards, marine maintenance/repair, and industrial service operations, being listed in supply systems defined with ISSA and IMPA codes can provide logistical convenience. The main compatible use focus is metal threaded connections and flange surfaces; for different materials or critical tolerances, a trial application beforehand is the right approach. When high viscosity, medium strength, and the ability to be disassembled with standard hand tools are considered together, it offers a reliable industrial adhesive/sealing solution that maintains ease of maintenance.