High Strength, Permanent | Up to 1" (25 mm) Fasteners | Sold as a Case of 24 Bottles

SONLOK 3271 is a fast-curing, high-strength anaerobic thread locking compound designed for permanent locking and sealing of threaded fasteners and retention of cylindrical parts. Engineered for fasteners up to 1" (25 mm) diameter, this red threadlocker delivers maximum holding power for critical assemblies exposed to vibration, shock, heat, and harsh chemicals.
Packaging: 50ml bottles, sold by the case of 24.

Manufactured by Parson Adhesives, SONLOK 3271 cures in the absence of air when confined between metal surfaces, forming a durable, corrosion-resistant bond that eliminates loosening, leakage, and the need for double nutting or welding. It meets applicable military specifications for high-strength thread locking in demanding industrial environments.

Key Features & Benefits

• High-strength, permanent anaerobic thread locker
• Fast cure with exceptional vibration and shock resistance
• Red color for easy identification of permanent assemblies
• Locks and seals threads to prevent corrosion and leakage
• Excellent resistance to heat, water, oils, fuels, gases, and chemicals
• Designed for large fasteners and critical joints
• Meets MIL-S-46163A Type I Grade K and MIL-S-22473E Letter Grade CVV

Typical Applications

• Fasteners up to 1" (25 mm) in diameter
• Transmission and engine block studs
• Valve sets, heavy equipment, and machinery
• Vibrating machines or moving components
• Permanent assemblies where removal is not intended

Comparable To

SONLOK 3271 is commonly used as an alternative to:

• Loctite® 271 High Strength Threadlocker by Henkel Loctite

It offers comparable permanent locking strength, chemical resistance, and vibration protection for critical threaded assemblies.

Adhesive Properties

Composition: Methacrylate Ester
Color: Red
Viscosity: 500 cps @ 25°C
(Brookfield RVT, Spindle 3 @ 20 rpm)
Specific Gravity: 1.11
Maximum Thread Size / Gap Fill: M20 / 1" / 0.15 mm
Flash Point: >100°C
Solvent Content: None
Shelf Life: 2 years

Curing Properties

Handling Cure Time: ~10 minutes
Functional Cure Time: 1–3 hours
Full Cure Time: 24 hours

Torque Performance (ISO 10964):
• Breakaway Torque (M10 steel): 28 N·m (230 lb·in)
• Prevail Torque (M10 steel): 31 N·m (320 lb·in)
• Breakloose Torque (pre-torqued to 5 N·m): 40 N·m (330 lb·in)
• Max. Prevail Torque (pre-torqued to 5 N·m): 57 N·m (510 lb·in)

Compressive Shear Strength (ISO 10123):
• Steel pins & collars: >8 N/mm² (>1,000 psi)

Service Temperature Range: −55°C to 150°C

Physical Properties

• Coefficient of Thermal Expansion: 80 × 10⁻⁶ (ASTM D696)
• Thermal Conductivity: 0.10 W/(m·K) (ASTM C177)
• Specific Heat: 0.30 kJ/(kg·K)

Chemical Resistance

(% Initial Strength Retained)

Application Instructions

• Ensure threads are clean, dry, and free of contaminants
• Apply sufficient product to fully fill the threads
• Best performance achieved in thin bond gaps
• Formulated to provide controlled friction and consistent torque/tension

Packaging & Storage

• Package Size: 50ml bottles
• Selling Unit: Case of 24 bottles
• Store unopened containers in a cool, dry place
• Ideal storage temperature: 46°F–82°F (8°C–28°C)
• Do not return unused material to the original container

SONLOK 3271 delivers maximum-strength, permanent thread locking with outstanding chemical and vibration resistance, making it a proven alternative to Loctite 271 for critical, high-load assemblies—now available by the case of 24 for professional and industrial use.