Loctite 2620

Overview

Loctite 2620 is a high-temperature, high-strength anaerobic threadlocker designed to lock and seal metal fasteners operating in very hot environments. It cures in the absence of air between close-fitting metal surfaces, forming a tough, cross-linked plastic in the thread gap.

Once cured, Loctite 2620:

• Prevents loosening from shock, impact and intense vibration

• Maintains threadlocking performance at temperatures far above standard red grades

• Seals the helix against fluid and gas leakage, even under thermal cycling

• Helps protect engaged threads from oxidation, fretting and corrosion

It’s the product you choose when your fasteners live near exhaust manifolds, turbines, burners or industrial heaters and still must stay locked for the life of the equipment.

Why choose Loctite 2620?

1) High strength for non-service fasteners
Loctite 2620 is a permanent-grade threadlocker. It delivers very high breakaway and prevailing torque on steel fasteners, making it ideal for joints where loosening is not acceptable and disassembly, if it happens at all, is done only during major overhauls.

2) Extra high-temperature capability
Compared with conventional high-strength red products, Loctite 2620 is engineered to retain meaningful strength at much higher temperatures, making it suitable for hot-end components and equipment that run near exhaust or flame paths.

3) Combined locking and sealing
By fully filling the space between male and female threads, Loctite 2620 locks the fastener and seals the thread path. It helps prevent leaks and slows corrosion, reducing the risk of seized or damaged fasteners during future service work.

4) Designed for demanding industrial environments
Loctite 2620 supports applications where fasteners see high load, temperature, vibration and thermal cycling simultaneously—conditions that would quickly defeat standard mechanical locking devices on their own.

5) Simple one-part application
Supplied as a single-component liquid in bottles or through metered systems, Loctite 2620 needs no mixing. Apply, assemble, and allow to cure at room temperature—no special curing equipment required.

Typical Applications

High-temperature automotive & powertrain

• Exhaust manifold bolts and studs

• Turbocharger brackets and hot-end fasteners

• High-temperature engine housings and shielding hardware

Industrial furnaces, burners & process heat

• Bolts and studs on ovens, furnaces, kilns and burners

• High-temperature flanges and housings in heaters and dryers

• Fasteners on thermal processing lines and incineration equipment

General permanent threadlocking at extreme temperature

• Joints where fasteners must never back off under heat and vibration

• Applications where standard high-strength red threadlockers are not enough

Loctite 2620 is intended for metal-to-metal threaded joints and is not recommended for plastics or for pure oxygen / strong oxidizer service.

How to Use Loctite 2620

Step 1 – Surface preparation

• Remove loose rust, dirt, scale and old threadlocker from the threads.

• Wipe off heavy oil, grease and anti-seize; a light “as-received” film may be tolerated, but for high-temperature duty, cleaner metal gives more reliable strength.

• For extremely demanding joints, solvent-clean and dry the fasteners before application.

Step 2 – Apply the threadlocker

• Shake the bottle briefly.

• Apply a continuous bead of Loctite 2620 to the male threads, fully covering the engagement length.

• For blind holes, place a small amount into the female threads so adhesive is driven throughout the joint during assembly.

Step 3 – Assemble and tighten

• Assemble the fastener and torque it to the specified value.

• Avoid loosening and re-tightening once curing has started, as this can disturb the adhesive film.

Step 4 – Cure and bring up to temperature

• Allow the joint to sit undisturbed until it reaches handling strength.

• For best performance, allow up to 24 hours at room temperature before exposing the assembly to full mechanical load or maximum operating temperature.

Step 5 – Disassembly (if ever required)

• Loctite 2620 is a high-strength, high-temperature permanent grade.

• Disassembly of larger fasteners normally requires:

  • Localized heating of the fastener area (only if compatible with your base materials and design) to significantly soften the adhesive, and

  • High torque with appropriate tools to loosen the fastener while the joint is still hot.

Safety & Handling

As with other high-strength, high-temperature anaerobic threadlockers, typical safety considerations for Loctite 2620 include:

• May cause eye and skin irritation on contact

• Repeated or prolonged exposure can cause skin sensitization in susceptible individuals

• Vapours or mists may cause mild respiratory irritation in poorly ventilated spaces

• Uncured product may be harmful to aquatic life if released uncontrolled

Basic precautions:

• Use only in well-ventilated areas.

• Avoid contact with skin and eyes; wear safety glasses and suitable protective gloves.

• Wash hands thoroughly after handling and before eating or drinking.

• Prevent uncured adhesive from entering drains or natural waterways.

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

Always consult and follow the latest Safety Data Sheet (SDS) for Loctite 2620 in your region.

FAQs

Q1: When should I choose Loctite 2620 instead of Loctite 272 or 266?
Choose Loctite 2620 when your fasteners operate in especially high temperature zones—for example near exhaust manifolds, burners or furnace doors—where even high-temp threadlockers like 272 or 266 may be at their limit. For lower temperature but still hot industrial service, 272 or 266 often suffice.

Q2: Is Loctite 2620 removable at all?
Loctite 2620 is a permanent high-strength grade. Small fasteners may be removed with strong tools, but the normal expectation is heat-assisted disassembly: you heat the fastener area to soften the adhesive, then apply high torque while still hot. If you need easy, routine removal, choose a medium-strength product instead.

Q3: What fastener sizes are best for Loctite 2620?
Loctite 2620 is typically used on medium and larger metal fasteners commonly found in engines, exhaust systems and process heaters. For very small screws, a low- or medium-strength grade is usually preferred; for very large studs, a high-viscosity heavy-duty high-temp grade may be specified.

Q4: Can Loctite 2620 be used on stainless steel or high-temperature alloys?
Yes. Loctite 2620 is designed for common high-temperature metals, including stainless steels and heat-resistant alloys used in exhaust and furnace construction. Cure speed can be slower on passive metals, so allow adequate time before loading, or consult Henkel for activator recommendations if very fast strength build-up is required.

Q5: Is Loctite 2620 oil- or fuel-tolerant?
For best results—especially at elevated temperature—threads should be clean and free of heavy contamination. Loctite 2620 may cope with slight residual films, but thick layers of oil, fuel or anti-seize will reduce strength and reliability. Clean critical fasteners to bare metal whenever possible.

Q6: Can I use Loctite 2620 on plastic threads or mixed metal/plastic joints?
No. Loctite 2620, like other anaerobic threadlockers, is formulated for metal-to-metal threads and may cause stress cracking in some plastics. It also does not cure properly on non-metallic threads. For plastic or mixed joints, use a product specifically designed for plastics.

Q7: Does Loctite 2620 also seal against high-temperature gas leaks?
Loctite 2620 locks and seals the thread path, helping reduce gas and fluid leakage through the helix. It significantly improves leak resistance of threaded joints, but it is not a replacement for properly designed flange gaskets or metal-to-metal seating surfaces in high-pressure or safety-critical systems.