LOCTITE® 567™: The High-Performance Thread Sealant for Metal Pipes and Fittings
Overview
In industrial piping systems, leaks are more than a maintenance nuisance — they are a direct threat to efficiency, safety, and cost control. Whether in chemical plants, refineries, marine systems, or utilities, engineers rely on precision sealing compounds to ensure operational reliability. Among the industry’s most trusted solutions is LOCTITE® 567™, a high-viscosity, anaerobic thread sealant formulated specifically for metal threaded fittings.
LOCTITE 567™ combines superior sealing performance with excellent material compatibility, particularly on stainless steel, aluminum, and other passive substrates. Designed to resist vibration, pressure, and temperature extremes, it provides long-term sealing integrity even under harsh industrial conditions.
Technology and Chemistry
LOCTITE 567™ is based on methacrylate ester technology — an anaerobic acrylic system that cures in the absence of air when confined between closely fitted metal surfaces.
This one-component compound requires no mixing or heat activation. Upon assembly, it reacts with metal ions to polymerize into a thermoset plastic, forming a solid, durable seal that prevents fluid or gas leakage through the threaded interface.
Key technical characteristics include:
| Property | Specification |
|---|---|
| Technology | Acrylic (Methacrylate Ester) |
| Appearance (uncured) | Smooth, creamy, off-white paste |
| Viscosity | High (thixotropic, non-drip) |
| Cure Method | Anaerobic (secondary cure with activator if required) |
| Strength Classification | Low strength (easy disassembly) |
| Temperature Resistance | –55 °C to +250 °C |
| Components | One-part, solvent-free formulation |
This chemistry allows LOCTITE 567 to develop robust seals even on substrates that traditionally inhibit anaerobic curing — such as stainless steel and plated metals — without the need for a primer in most cases.
Application Scope
LOCTITE 567 is engineered for sealing and locking metal tapered threads and fittings, preventing loosening or leakage caused by vibration, thermal cycling, or mechanical shock.
It is widely used in:
- Petroleum refining and chemical processing plants
- Gas compression and distribution networks
- Pulp and paper industries
- Water and waste treatment systems
- Power generation and utilities
- Marine, automotive, and heavy equipment maintenance
The product’s high lubricity prevents galling on stainless steel and aluminum threads — a critical advantage in assemblies where thread seizure or cold welding can lead to expensive downtime or rework.
Performance Benefits
LOCTITE 567 is distinguished by a set of engineering advantages that simplify installation, improve reliability, and extend equipment service life.
1 Instant Low-Pressure Seal
Unlike traditional pastes or Teflon tapes, LOCTITE 567 provides an immediate low-pressure seal upon assembly, allowing systems to be pressurized during the curing process. This feature significantly reduces maintenance turnaround time.
2 Vibration and Shock Resistance
Once cured, the compound forms a polymer matrix that resists micro-movement caused by vibration or thermal expansion. It prevents both loosening and leakage, maintaining joint integrity in dynamic service environments.
3 High Lubricity and Anti-Galling
The smooth, creamy texture ensures uniform application and acts as a lubricant during tightening. On stainless steel and aluminum, this property prevents galling and thread damage — a common problem when mechanical friction generates localized heat.
4 Chemical and Thermal Stability
LOCTITE 567 withstands exposure to oils, coolants, fuels, hydraulic fluids, and various process chemicals. Its operational temperature range extends to approximately +250 °C, making it suitable for high-temperature steam or gas lines.
5 Controlled Strength for Easy Disassembly
Although it forms a permanent seal, LOCTITE 567 is classified as low strength, allowing fittings to be disassembled using standard hand tools during scheduled maintenance. This feature differentiates it from higher-strength threadlockers used for permanent joints.
Typical Properties and Pressure Performance
| Property | Typical Value | Test Method |
|---|---|---|
| Breakaway Torque (M10 steel bolts) | 12 N·m | ISO 10964 |
| Prevailing Torque (M10) | 4 N·m | ISO 10964 |
| Pressure Resistance | >10,000 psi (690 bar) | Hydraulic test |
| Cure Speed (on steel, 25 °C) | Functional strength: 1–3 h / Full cure: 24 h | ISO 10964 |
| Gap Fill Capacity | Up to 0.25 mm | |
| Service Temperature Range | –55 °C to +250 °C |
These values are typical and should not be used for specification limits. Actual performance varies with substrate, thread size, and environmental conditions.
Recommended Use and Application Procedure
To ensure consistent sealing performance, follow the procedure below:
- Surface Preparation
Clean all threads thoroughly. Remove oil, dirt, cutting fluids, or oxide layers using a suitable solvent or LOCTITE® cleaner. While the product tolerates light contamination, clean surfaces enhance cure speed and final strength. - Application
Apply a continuous bead of LOCTITE 567 to the male (external) threads, beginning one thread from the leading edge. For larger fittings, apply circumferentially around the first few threads. - Assembly
Assemble the parts immediately to avoid premature curing. Tighten to the required torque using standard tools. - Curing
- At room temperature (~25 °C), functional strength is typically achieved within 1–3 hours.
- Full cure is reached in approximately 24 hours.
- For stainless steel or other passive metals, curing may be accelerated by using LOCTITE® 7649 Activator.
- Testing and Commissioning
The joint is sealed for low-pressure service immediately. For critical or high-pressure applications, allow full cure time before pressurizing the system.
Comparison: LOCTITE 567 vs LOCTITE 577
While both products belong to LOCTITE’s family of anaerobic thread sealants, their formulations and target applications differ.
| Characteristic | LOCTITE 567 | LOCTITE 577 |
|---|---|---|
| Primary Application | Tapered metal threads | Straight or coarse threads |
| Strength | Low | Medium |
| Temperature Resistance | Up to 250 °C | Up to 180 °C |
| Thread Type Compatibility | Tapered (NPT, BSPT) | Straight (BSPP, metric) |
| Viscosity | High, non-sag | Medium-high |
| Disassembly | Easy (hand tools) | Moderate |
| Recommended Metals | Stainless steel, aluminum, plated | Steel, brass, iron |
| Oil Tolerance | High | Moderate |
Summary:
Choose LOCTITE 567 when sealing metal tapered threads, particularly stainless steel fittings or high-temperature systems where controlled disassembly is important.
Use LOCTITE 577 for straight threads, coarse fittings, or where higher locking strength is required.
Stainless Steel Compatibility
One of LOCTITE 567’s most valuable attributes is its superior performance on stainless steel — a notoriously difficult material for many anaerobic sealants due to its low surface reactivity.
- Fast, reliable curing: 567’s formulation is optimized to polymerize effectively on passive substrates without extensive surface activation.
- Anti-galling action: Its lubricating film reduces friction and prevents metal transfer between threads during tightening.
- Corrosion protection: Once cured, it creates a hermetic seal that blocks moisture and oxygen ingress, minimizing corrosion risk in stainless systems.
These properties make LOCTITE 567 the preferred solution for stainless-steel pipework in food processing, marine, and petrochemical installations.
Advantages over Conventional Sealing Methods
1 Versus PTFE (Teflon) Tape
While PTFE tape has long been used in plumbing and maintenance, it poses several limitations:
| Issue | PTFE Tape | LOCTITE 567 |
|---|---|---|
| Risk of shredding / contamination | High | None |
| Vibration resistance | Poor | Excellent |
| Sealing micro-leaks | Limited | Complete |
| Ease of rework | Moderate | Excellent (controlled strength) |
| Temperature tolerance | Up to 200 °C | Up to 250 °C |
| Stainless steel galling prevention | None | Yes |
2 Versus Pipe Dope and Paste Sealants
Traditional pastes often rely on solvents that shrink as they dry, leading to potential leaks over time.
LOCTITE 567 cures into a solid thermoset polymer that neither shrinks nor creeps, providing long-term dimensional stability and consistent sealing performance.
Best Practices for Industrial Users
To maximize reliability and minimize downtime:
- Store properly: Keep sealed containers between 8 °C and 21 °C in a dry environment.
- Avoid over-application: Excess sealant may extrude internally and should be wiped away before curing.
- Plan for cure time: Allow 24 hours before subjecting joints to maximum pressure or temperature.
- Use activators when needed: For cold environments or passive substrates, LOCTITE 7649 improves cure rate.
- Follow standard torque procedures: The product’s lubricity can slightly alter torque values; confirm with equipment manufacturer guidelines.
Industrial Value Proposition
For engineering and maintenance teams, LOCTITE 567 delivers measurable operational value:
- Reduced leakage and rework — eliminates repeated maintenance caused by failed seals.
- Lower installation torque — lubricating properties minimize thread friction.
- Extended equipment life — prevents corrosion, galling, and thread wear.
- Improved safety and environmental compliance — leak-free joints reduce exposure to hazardous fluids or gases.
- Simplified inventory — one product suitable for multiple metals and thread types.
In industries where downtime equates to financial loss, these benefits translate directly into higher reliability and lower total cost of ownership.
Equivalent Products and Alternatives
While LOCTITE 567 sets the industry standard, several products exist in the same performance class. Typical equivalents include:
- Permabond A131 – anaerobic thread sealant for metal pipes
- Hylomar PL32M – jointing compound for metal threads
- 3M Scotch-Grip Pipe Sealant 1651 – medium-strength anaerobic formulation
However, LOCTITE 567 remains the benchmark for stainless-steel thread sealing due to its unique anti-galling chemistry and extensive global approvals.
Regulatory and Safety Information
LOCTITE 567 is UL Classified (MH8007, ULC MH27131) and KIWA GASTEC QA AR 214 certified for gas applications.
Safety precautions should always be observed:
- Avoid skin and eye contact.
- Use in well-ventilated areas.
- Refer to the Material Safety Data Sheet (MSDS) for complete hazard and handling details.
Conclusion
In modern industrial environments, reliability is non-negotiable.
LOCTITE® 567™ provides the assurance that every threaded metal connection — from refinery pipelines to marine engine fittings — remains sealed, stable, and serviceable.
Its combination of high lubricity, oil tolerance, thermal endurance, and compatibility with stainless steel positions it as the professional’s choice for precision thread sealing.
Whether you are designing new process systems or maintaining existing installations, LOCTITE 567 delivers a solution that meets both engineering and economic performance standards.