Flange bolted connections are widely used in pipelines, hydraulic equipment, compressors and assembly of various mechanical assemblies. Common failure modes include bolt loosening under vibration, medium leakage at mating surfaces, fretting corrosion and thread seizing. Conventional solutions such as spring washers, toothed gaskets and cotter pins only prevent loosening by increasing friction, and cannot completely eliminate risks of loosening and sealing failure after long-term operation. Proper selection of anaerobic adhesives can deliver multiple functions including thread locking, sealing and corrosion protection simultaneously.
Bolt Thread Area: Thread Locking Adhesive
Flanges are continuously subjected to pressure fluctuations, vibration and alternating hot and cold conditions, which easily lead to preload attenuation and loosening of bolts.
Apply anaerobic thread locking adhesive of appropriate strength onto thread engagement zones:
- Fill thread clearances to block air ingress and isolate moisture and oil contaminants;
- Form a tough adhesive layer after curing to lock bolts against loosening;
- Prevent direct metal-to-metal contact of threads and restrain fretting corrosion and thread seizing.
Adhesive Selection Recommendations
- Disassembly required for future maintenance: Medium-strength removable thread locker;
- Long-term maintenance-free service with zero tolerance for loosening: High-strength permanent thread locking grade.
Flange Mating Surface: Flange Sealant
Tiny flatness errors exist in machined flange surfaces, and leakage tends to occur once gaskets age under prolonged compression.
Flexible anaerobic flange sealants fill micro-gaps on flange faces, serving as a replacement for or auxiliary to conventional rubber and metal gaskets. The cured adhesive features elasticity to accommodate minor flange deformation. It resists oil, water, refrigerants, acids and alkalis, and effectively prevents interfacial leakage.
