Fasto A742 - Thread Sealants

Fasto A742 – Reliable Locking & Sealing for Hydraulic and Pneumatic Pipe Threads

Fasto A742 is a single-component, medium strength anaerobic pipe thread sealant designed to lock and seal fine to medium pitch metal pipe threads. It cures in the absence of air when confined between close-fitting metal surfaces, creating a vibration-resistant, leak-proof seal while still allowing controlled disassembly for servicing.

Fasto A742 provides an almost instant low-pressure seal and, once fully cured, can seal up to the bursting pressure of the pipe, making it ideal for hydraulic and pneumatic systems.

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Key Features

  • Medium Strength – Serviceable Joints
    Enables easier disassembly compared to high-strength sealants.
  • Anaerobic Cure Technology
    Cures only between metal threads; no surface curing.
  • Instant Low-Pressure Sealing
    Seals up to 2 bar within ~20 minutes.
  • High Final Pressure Resistance
    Seals up to the bursting pressure of the pipe (e.g., 10,000 psi when fully cured).
  • Thixotropic, Controlled Viscosity (~700 cPs)
    Prevents run-off and migration on vertical pipe joints.
  • Wide Temperature Resistance
    Continuous service from -50°C to +150°C.
  • Excellent Chemical & Solvent Resistance
    Resistant to oils, fuels, brake fluid, alcohols, acetone, and water.
  • Corrosion Protection
    Prevents fretting and corrosion on threaded pipe joints.

Benefits

  • Prevents leakage and vibration loosening in pipe systems
  • Ideal for hydraulic and pneumatic pipe threads
  • Allows maintenance-friendly disassembly
  • Improves system reliability and safety
  • Suitable for industrial and automotive fluid systems
Primary Application Sub-Applications Functional Purpose Key Performance Advantage
Hydraulic Pipe Thread Sealing Hydraulic fittings, pressure lines Seal and lock threaded joints Almost instant low-pressure seal; seals up to bursting pressure after full cure
Pneumatic System Pipe Sealing Pneumatic lines, air fittings Prevent air leakage and vibration loosening Medium strength with reliable vibration resistance
Fine to Medium Pitch Pipe Threads Pipe threads up to Ø 15 mm Secure sealing of close-fitting threads Optimized viscosity for fine & medium pitch
Serviceable Pipe Assemblies Joints requiring maintenance Enable disassembly and servicing Medium break & prevailing torque
Vibration-Exposed Pipe Joints Pumps, compressors, machinery piping Prevent loosening during operation Anaerobic locking and sealing combined
Oil & Solvent-Exposed Pipe Systems Oil, fuel, solvent handling lines Maintain seal integrity in harsh media Excellent chemical & solvent resistance
Industrial Fluid Transfer Lines Process piping, utility systems Long-term leak prevention Performs up to high operating temperatures

Surface Preparation

  • Ensure threads are clean, dry, and free from oil, grease, and contaminants.
  • Proper cleaning is essential for optimum sealing and cure performance.

Application Method

  1. Apply Fasto A742 to all engaged pipe threads.
  2. Assemble the joint and tighten to the specified torque within 10 minutes of application.
  3. Allow the joint to cure under anaerobic (air-excluded) conditions.
  4. Wipe off excess sealant from the outside of the joint.

Curing Guidelines

  • Fixture time: 2–10 minutes
  • Low-pressure seal: up to 2 bar after ~20 minutes
  • Full cure: 12 hours
  • Maximum recommended gap: 0.15 mm

Additional Notes

  • Cure speed depends on temperature, substrate, and bond gap.
  • At temperatures below 5°C or on inert metals (e.g., stainless steel, aluminum), use Fasto AP49 / AP69 Activator to accelerate cure (note: activator may reduce final strength by up to 30%).
  • Not recommended for pure oxygen or chlorine systems.
  • Not suitable for certain plastics due to potential stress cracking—testing is recommended.

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