loctite 577

Loctite 577

Applications:Pipe sealing; Thread sealing
Breakaway torque, Steel, M10:33.0 N·m (295.0 in./lb.)
Color:Yellow
Cure type:Anaerobic cure
Key characteristics:Chemical resistant; Fluorescent; General purpose; Immediate low pressure sealing; Strength: medium strength; Surface contamination-tolerant; Temperature: high temperature; Thixotropic
Operating temperature:-55.0 °C – 150.0 °C (-65.0 °F – 300.0 °F)
Physical form:Paste
Recommended for use with:Metal; Metal: passive metal; Thread type: tapered
Viscosity, 20 RPM:25000.0 mPa·s

Overview

Loctite 577 is a medium-strength anaerobic thread sealant designed for metal pipe threads and fittings. It cures in the absence of air between metal surfaces and forms a tough, chemical-resistant polymer that seals and locks the thread interface.

Once cured, Loctite 577:

  • Helps prevent leaks of liquids and gases along the thread helix

  • Resists loosening from vibration, thermal cycling and pressure pulsation

  • Protects engaged threads from corrosion and galling over time

It replaces PTFE tape and traditional “pipe dopes” in many applications, providing cleaner assembly and more repeatable sealing performance.

Why choose Loctite 577?

1) Medium strength – sealed yet serviceable
Loctite 577 provides strong sealing while remaining removable with normal tools for maintenance or rework. It secures fittings against vibration but still allows disassembly during planned shutdowns.

2) Suitable for tapered and straight metal threads
The product is formulated for metal threads on pipework, manifolds, valve bodies and fittings – whether tapered pipe threads or straight threads designed to seal in the flank area.

3) Thixotropic, non-drip formula
Loctite 577 is thixotropic: it flows under shear during assembly but stays in place on the threads at rest. That means no running on vertical joints and minimal migration into internal passages.

4) Clean alternative to tape and paste
Unlike PTFE tape, Loctite 577 does not shred, bunch up, or extrude into valves and filters. It stays in the threads where it belongs, cutting down on contamination and rework.

5) One-part, room-temperature cure
Supplied as a single-component product, there is no mixing or ratio control. Apply directly from the bottle, assemble, and let it cure at ambient temperature.

Typical Applications

Loctite 577 is widely used for metal threaded pipe connections in:

  • Hydraulic and pneumatic systems – manifolds, cylinders, valve blocks, actuators

  • Plant utilities – compressed air, water, inert gases and general service lines

  • Pumps and compressors – suction and discharge pipework, lubrication and cooling lines

  • Process and industrial equipment – filters, heat exchangers, dryers, skids and machinery

Loctite 577 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 577

Step 1 – Surface preparation

  • Clean threads to remove loose dirt, rust, old tape or sealant.

  • Wipe away heavy oil, grease and cutting fluids.

  • A light oil film is often tolerated, but cleaner metal gives more consistent sealing and strength.

Step 2 – Apply the sealant

  • Shake the bottle briefly.

  • Apply a continuous bead of Loctite 577 around the male threads, covering the area that will be engaged.

  • Avoid flooding the first thread to reduce the chance of excess product entering the system.

Step 3 – Assemble and orient

  • Assemble the joint and tighten to the specified torque or to the correct orientation (for elbows, tees, gauges).

  • The thixotropic consistency helps the product stay in the threads during assembly.

Step 4 – Cure and pressure test

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

  • Follow recommended times before pressure testing or putting the system into full service (larger diameters and colder conditions may need longer).

Step 5 – Disassembly

  • During maintenance, fittings sealed with Loctite 577 are generally removable with normal hand tools.

  • If the joint has been in service for a long time or at elevated temperature, extra leverage may be required, but the cured product typically helps prevent severe thread seizure.

Safety & Handling

Typical safety aspects for anaerobic sealants like Loctite 577:

  • May cause skin and eye irritation on contact

  • Repeated or prolonged contact can cause skin sensitisation in some individuals

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

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

Good practice

  • Use in a well-ventilated area.

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

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

  • Do not pour uncured sealant into drains or natural waterways.

  • 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 577 in your region.

FAQs

Q1: What is Loctite 577 used for?
Loctite 577 is used to lock and seal metal pipe threads and fittings, preventing leaks of liquids and gases and resisting vibration in industrial and plant systems.

Q2: How is Loctite 577 different from PTFE tape?
PTFE tape can shred, bunch up or extrude into valves and filters, and its performance depends heavily on installer technique. Loctite 577 cures into a solid polymer seal inside the threads, giving more consistent sealing and reducing the risk of stray tape fragments.

Q3: Is Loctite 577 removable?
Yes. Loctite 577 is a medium-strength sealant. Fittings can normally be disassembled using standard hand tools, making it suitable for systems that will be serviced in the future.

Q4: Can I use Loctite 577 on stainless steel and brass fittings?
Yes. Loctite 577 is suitable for steel, stainless steel, brass and many other metals commonly used in pipework and fittings. Always confirm compatibility for special alloys.

Q5: Is Loctite 577 suitable for plastic pipes or plastic fittings?
No. Anaerobic products like Loctite 577 are formulated for metal threads and can cause stress cracking in some plastics. Use a sealant designed specifically for plastic piping when needed.

Q6: Can Loctite 577 handle high pressure?
When properly cured on correctly machined metal threads, Loctite 577 is designed for high-pressure sealing in many fluid and gas systems. Always validate performance in your own application and follow the pressure limits published in the Technical Data Sheet.

Q7: Do I still need thread tape if I use Loctite 577?
No. Loctite 577 is intended to replace PTFE tape or pipe dope in most metal-threaded joints. Using tape and sealant together is usually unnecessary and can interfere with correct sealing.

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