Loctite 277

Loctite 277

Strength: High strength, local heating is required for disassembly
Temperature range: 150°C
Maximum bolt size: M80
Packaging: 50 ml/250 ml/1000ml
Color: Red
Viscosity (cP) at 20 rpm: 7000
Thixotropy: No
Breakaway torque/average dismantling torque, M10 steel nuts and bolts (N.m, lb.in): 32/32 N.m ; 280/280 lb.in
Temperature range: -55°C to 180°C (-65°F to 360°F)
Fixture time (min): 45

Overview

Loctite 277 is a red, high-strength, high-viscosity, methacrylate-based anaerobic threadlocker designed for the permanent locking and sealing of threaded fasteners. It cures when confined between close-fitting metal surfaces in the absence of air and is especially suited to large bolts and studs greater than 25 mm (1″).

Once cured, Loctite 277 forms a tough thermoset plastic in the thread gap that:

  • Resists loosening from shock, vibration and dynamic loading

  • Seals the thread helix against fluids and gases

  • Helps protect threads from corrosion and fretting

Why choose Loctite 277?

1) Purpose-built for large bolts and studs
Loctite 277 is specifically recommended for large fasteners, typically M25 and above and up to about 1½” (36 mm). The high viscosity helps wet coarse thread flanks and stay in place on big hardware, minimizing run-off and migration.

2) Permanent-strength retention for heavy-duty service
As a high-strength grade, 277 delivers very high breakaway and prevailing torque, making it ideal anywhere loosening would be costly or dangerous—like pump housings, gearboxes, presses, heavy vehicles and structural frames.

3) Oil-tolerant and suited to real-world production
277 is a one-part anaerobic adhesive that tolerates slight contamination with industrial oils, such as cutting oils or corrosion-prevention oils on metal parts. Light films are usually acceptable, though heavy contamination should still be cleaned.

4) Threadlocking and sealing in one step
By filling the entire thread engagement, Loctite 277 locks and seals in a single operation. It helps prevent leakage and protects threads from rust and corrosion over the life of the equipment.

5) Military-grade performance and easy inspection
Loctite 277 is tested to MIL-S-46163A Type I Grade L and classified under ASTM D5363, giving confidence for demanding and legacy specifications. The red adhesive also fluoresces under UV light, making it easy to verify application during quality checks.

Typical Applications

Large, critical fasteners

  • Large bolts and studs on pumps, compressors and gearboxes

  • Studs into motor housings, engine blocks and heavy frames

  • Structural bolted joints on presses, heavy equipment and off-road machines

High-vibration environments

  • Fasteners on rotating equipment subject to continuous shock and vibration

  • Joints where mechanical locking devices alone (spring washers, lock nuts) may not be sufficient

General permanent threadlocking

  • Metal fasteners where permanent retention is required and disassembly, if ever needed, can be done with heat and heavy tools

  • Applications demanding long-term sealing, corrosion protection and high torque strength

Loctite 277 is intended for metal-to-metal threads and is not recommended for plastics or non-metallic fasteners.

How to Use Loctite 277

Step 1 – Surface preparation

  • Remove loose rust, dirt, old threadlocker and heavy grease.

  • Wipe away thick oil, cutting fluid and anti-seize compounds.

  • Light preservative oil films are usually acceptable, but cleaner metal gives higher and more consistent strength.

Step 2 – Product application

  • Shake the bottle before use.

  • Apply a continuous bead of Loctite 277 along the male threads, covering the full engagement length.

  • For blind holes, apply some product into the female threads as well so it is pushed up through the joint as the fastener is installed.

Step 3 – Assembly and tightening

  • Assemble the joint and tighten to the specified torque.

  • Avoid backing off or re-adjusting once the product starts to fixture.

Step 4 – Cure and return to service

  • Allow sufficient time for fixture (handling strength) and full cure.

  • For critical joints, plan for up to 24–72 hours at room temperature, depending on metal type and temperature, before applying full load or pressure.

Step 5 – Disassembly (if ever required)

  • Loctite 277 is high strength, so disassembly generally requires:

    • Heating the fastener area to roughly 250–300 °C (480–570 °F) where the base materials permit.

    • Loosening with appropriate tools while the joint is still hot.

Safety & Handling

According to Safety Data Sheets for Loctite 277, typical hazards include serious eye irritation and respiratory tract irritation; prolonged or repeated contact may cause skin irritation.

Basic precautions:

  • Avoid contact with skin and eyes; wear safety glasses and chemical-resistant gloves.

  • Use only in well-ventilated areas; avoid breathing vapour or mist.

  • Wash hands thoroughly after handling.

  • Do not allow uncured product to enter drains or the environment.

  • Store in a cool, dry place, away from heat, ignition sources and direct sunlight, in the original, tightly closed container.

Always read and follow the latest SDS for your country or region before use.

FAQs

Q1: When should I choose Loctite 277 instead of other red threadlockers?
Choose Loctite 277 when you are dealing with large bolts and studs and need very high strength plus extra resistance to migration on big threads. For smaller fasteners or general high-strength use, other grades like Loctite 271/263 may be preferred.

Q2: Is Loctite 277 permanent?
Yes. Loctite 277 is classified as a high-strength, permanent threadlocker. Small fasteners may still be removed with heavy tools, but for large bolts you should plan on using localized heat before disassembly.

Q3: Does Loctite 277 work on stainless steel and plated fasteners?
Yes. 277 is methacrylate-based and designed for all common metals, including stainless steel and plated surfaces. Cure is slower on passive metals, so allow longer cure time or consider a primer/activator if you need faster strength build-up.

Q4: How oil-tolerant is Loctite 277 really?
Loctite 277 can tolerate slight contamination from industrial oils, meaning it can still cure and perform on reasonably clean “as-received” parts. Heavy oil, grease or anti-seize should be removed, otherwise bond strength and cure may be compromised.

Q5: Can I use Loctite 277 for small screws and fine threads?
Technically it will cure, but 277 is optimized for large threads and high torque. On small screws or fine threads, breakaway torque can be excessively high and risk damage on removal. For smaller fasteners, a medium-strength or lower-viscosity threadlocker is usually a better choice.

Q6: Does Loctite 277 also seal against leaks?
Yes. By filling the thread gap, 277 locks and seals in one step, helping prevent leakage of liquids and gases and protecting threads from corrosion. It’s not a replacement for full flange gaskets, but it is effective at sealing through the thread helix.

Q7: Is Loctite 277 suitable for plastics or non-metallic fasteners?
No. Like other anaerobic threadlockers, Loctite 277 is designed for metal-to-metal joints. It will not cure properly on plastics and may cause stress cracking in some plastic materials. Use a plastic-safe adhesive for those applications.

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