Overview
Loctite 565 is a medium-strength, anaerobic thread sealant formulated as a white, paste-like compound for sealing coarse metal pipe threads. It cures in the absence of air between metal surfaces to form a tough polymer that fills the gaps between the flanks of the threads.
Once cured, Loctite 565:
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Helps prevent leaks of liquids and gases along the thread helix
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Resists loosening from vibration and thermal cycling
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Protects engaged threads from corrosion, galling and seizure
It is a practical alternative to PTFE tape and traditional pipe dopes, providing cleaner assembly and more consistent sealing performance.
Why choose Loctite 565?
1) Designed for coarse pipe threads
The high viscosity, paste-like consistency of Loctite 565 makes it ideal for coarse metal threads commonly used on pipework and fittings. It packs into the spaces between thread flanks and stays where you put it.
2) Medium strength, serviceable joints
Loctite 565 gives a secure, pressure-resistant seal while allowing fittings to be disassembled with normal hand tools during maintenance or system modification.
3) Non-running, non-dripping formula
Because it is thixotropic and paste-like, Loctite 565 won’t run or drip on vertical or overhead joints. This reduces mess and keeps the sealant in the thread where it belongs, not inside the line.
4) Locks and seals in one step
By filling the clearances in the thread, the product both locks the fitting against vibration-induced loosening and seals the path against leakage, often allowing you to eliminate separate locking devices and pipe dopes.
5) One-part, easy application
Supplied as a single-component product, there is no mixing or special equipment. Apply from the tube or bottle, assemble the joint, and let it cure at ambient temperature.
Typical Applications
Loctite 565 is suitable for metal coarse-thread pipe connections in:
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Hydraulic and pneumatic systems
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Manifolds, valve blocks, cylinders and actuators
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Plant utilities and general service
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Water, air, inert gas and many non-aggressive industrial fluids
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Pumps, compressors and process equipment
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Suction and discharge lines, lubrication and cooling circuits
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Maintenance & repair work
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Replacement valves, gauges, plugs and fittings during MRO shutdowns
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Loctite 565 is intended for metal threads only and is not recommended for plastic pipe threads or for pure oxygen / strong oxidizer service.
How to Use Loctite 565
Step 1 – Surface preparation
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Ensure threads are correctly cut and in good mechanical condition.
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Remove old tape, dried sealant, dirt and corrosion from the threads.
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Wipe away heavy oil, grease and cutting fluid; a light residue may remain, but cleaner surfaces give more predictable results.
Step 2 – Apply the sealant
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Squeeze a small amount of Loctite 565 from the tube or bottle.
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Apply a continuous bead around the male threads, covering the area that will be engaged.
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Avoid overloading the first thread to reduce the chance of excess product entering the system.
Step 3 – Assemble and orient
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Assemble the joint and tighten to the specified torque.
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Orient elbows, tees and gauges to their final position.
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The paste consistency gives smooth tightening and helps avoid thread galling.
Step 4 – Cure and pressure test
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Allow the joint to sit until it reaches handling strength.
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For many standard applications, you can perform a low-pressure test after a short time; for full design pressure and safety-critical joints, follow the cure times recommended in the data sheet and your plant procedures.
Step 5 – Disassembly
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During maintenance, fittings sealed with Loctite 565 are generally removable with normal hand tools.
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After long service or elevated temperature exposure, extra leverage may be needed, but the product typically helps prevent severe thread seizure compared to dry assembly.
Safety & Handling
As with other anaerobic sealants, Loctite 565 should be handled with standard industrial precautions:
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May cause skin and eye irritation on contact
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Prolonged or repeated contact can lead to skin sensitisation in some individuals
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Vapours or mists may cause mild respiratory irritation in poorly ventilated areas
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Uncured product may be harmful to aquatic life if released uncontrolled
Good practice
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Use in a well-ventilated area.
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Avoid contact with skin and eyes; wear safety glasses and suitable protective gloves.
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Wash hands thoroughly after handling and before eating or drinking.
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Do not pour uncured product into drains or natural waterways.
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Store in the original, tightly closed container, in a cool, dry place away from heat and direct sunlight.
Always follow the latest Safety Data Sheet (SDS) for Loctite 565 in your region.
FAQs
Q1: What is Loctite 565 mainly used for?
Loctite 565 is used to seal and lock coarse metal pipe threads, preventing leaks of liquids and gases while resisting vibration and thermal cycling in industrial and plant systems.
Q2: How is Loctite 565 different from Loctite 577 or PTFE tape?
Loctite 565 is a white, paste-style sealant optimized for coarse metal threads, whereas Loctite 577 is a medium-viscosity liquid. Compared with PTFE tape, 565 doesn’t shred or extrude, and it provides a more uniform, permanent seal in the thread flanks.
Q3: Is Loctite 565 removable?
Yes. Loctite 565 is medium strength, so joints can typically be disassembled using standard pipe tools. It offers solid sealing and resistance to vibration but is not classed as a permanent, high-strength lock.
Q4: Can Loctite 565 be used on stainless steel and brass fittings?
Yes. Loctite 565 is suitable for steel, stainless steel, brass and other common metal fittings used in pipework. Always check for compatibility with any special alloys or surface treatments.
Q5: Can I use Loctite 565 on plastic pipe threads or plastic fittings?
No. Anaerobic products like Loctite 565 are designed for metal threads and may cause stress cracking in some plastics. For plastic piping or mixed metal/plastic joints, use a sealant specifically approved for plastics.
Q6: Does Loctite 565 withstand high pressure?
When properly applied and fully cured on correctly machined metal threads, Loctite 565 is designed for high-pressure sealing in many industrial systems. Always validate performance in your own application and follow the limits in the Technical Data Sheet.
Q7: Do I still need PTFE tape if I use Loctite 565?
No. Loctite 565 is intended to replace PTFE tape and traditional pipe dope in most metal-thread applications. Using both together is unnecessary and can interfere with correct sealing.
