Thread Sealants

Gap Filling & Lubricating

Tapes, Liquid, and Compounds

Thread Sealants

Thread sealants are applied to the threads of pipe fittings and connectors to fill the microscopic gaps between mating threads, preventing the leakage of liquids and gases under pressure. Unlike threadlockers, which are formulated to prevent a fastener from loosening under vibration, thread sealants are formulated primarily to create a leak-tight seal, with fastener retention as a secondary effect rather than the goal.

Most thread sealants use anaerobic chemistry, curing in the absence of oxygen when confined between metal threads, though PTFE-based paste and tape formulations are also common for lower-pressure or more easily serviced connections. Selection depends on the thread material, expected pressure and medium (liquid, gas, or fuel), service temperature, and whether the joint needs to be disassembled for maintenance.

13 products

  • PERMABOND® MH052 Anaerobic Thread Sealant

    PERMABOND® MH052 Anaerobic Thread Sealant

    • BAM and DVGW approved anaerobic thread sealant for oxygen, natural gas, and LPG systems
    • Leak-tight sealing performance up to the burst pressure rating of the pipe
    • Particle-free anaerobic formulation resists shrinkage, cracking, and shredding unlike pipe dope and PTFE tape
  • Loctite 580 Pipe Sealant

    Loctite 580 Pipe Sealant

    • One-Component Sealing System
    • Low Pressure Sealing for Inactive Metals
    • Room-Temperature Sealing Cure
  • LOCTITE 190017

    LOCTITE 190017

    • Anaerobic Adhesive Technology
    • Above 100 deg C Flash Point
    • Clear Liquid Formulation
  • LOCTITE 545

    LOCTITE 545

    • One-Component Sealing System
    • Thread Sealing and Locking
    • Assembly Lubricity Sealant Formulation
  • LOCTITE 554

    LOCTITE 554

    • High Solvent Resistance
    • Thread Sealing Up to 50mm
    • One-Component Sealing System
  • LOCTITE 566

    LOCTITE 566

    • Low-Strength Thread Sealing
    • Vibration-Resistant Thread Sealing
    • One-Component Sealing System
  • LOCTITE 567

    LOCTITE 567

    • High-Lubricity Thread Assembly
    • Anaerobic Thread Sealing
    • High-Temperature Service Sealant Formulation
  • LOCTITE 569

    LOCTITE 569

    • Low-Viscosity Sealing Application
    • Vibration-Resistant Thread Sealing
    • Broad Fluid Resistance
  • LOCTITE 592

    LOCTITE 592

    • High-Lubricity Thread Assembly
    • Immediate Low-Pressure Seal
    • Elevated Temperature Fluid Resistance
  • PERMABOND LH050

    PERMABOND LH050

    • Up to 1000 psi Instant Air Seal
    • PTFE Non-Shredding Pipe-Dope Alternative
    • UL Gas/Fuel/Sprinkler Classification
  • PERMABOND LM012

    PERMABOND LM012

    • Unfilled PFAS-Free Anaerobic Threadsealant
    • Sensitive High-Pressure Hydraulic-System Sealing
    • MIL-S-22473/ASTM D5363 Compliance Scope
  • LOCTITE 542

    LOCTITE 542

    • Low-Viscosity Fine-Thread Sealing
    • Anaerobic One-Part Application
    • Medium-Strength Serviceable Retention
  • LOCTITE 571

    LOCTITE 571

    • Medium-Viscosity Tapered-Thread Sealing
    • Anaerobic One-Part Retention
    • Fluid-Exposure Strength Retention

Product selector guide

Product System Work / Skin Time Hardness Tensile Strength [MPa] Elongation [%] Operating Temperature [°C] Key Differentiator
3M 08463 2K Flexible PU Foam 40 sec – – – –20 to 82 1 hr cure; closed-cell foam
3M 540 1K Moisture Cure 60–90 min 40 Shore A 2.1 >600 –40 to 90 ~3 mm / 24 hr cure rate
3M 550FC 1K Moisture Cure 50–90 min 45 Shore A 3.1 >600 –40 to 90 Fast cure; ~4 mm / 24 hr cure rate
3M 560 1K Moisture Cure 50–60 min 55 Shore A 4.0 >300 –40 to 90 Higher-strength elastic bonding
3M RP2110 2K Urethane Repair Paste 10 min 70 Shore A – – – 1:1 mix; 6 hr tack-free / 24 hr full cure
3M TE031 1K Reactive PUR 2 min open time 50 Shore D 26.9 725 – Applied at ~121°C; ~30 sec handling strength
BOSTIK 1100 FS 1K Moisture Cure 70 min work / 90 min tack-free 40–45 Shore A 1.65 850 –40 to 82 ±25% joint movement
BOSTIK 915 1K Moisture Cure 60 min work / 4 hr skin 42 Shore A 0.92 685 –40 to 66 ±35% joint movement; ASTM C920 Class 35
BOSTIK 920 1K Moisture Cure 70 min work / ~6 hr tack-free 38 Shore A 1.24 950 –40 to 82 ±25% movement; marine above/below waterline
CONATHANE AD-6415 2K PU Adhesive / Sealant – – – – – 1:2 processing format; filtration membrane bonding
DEVCON FLEXANE 94 2K Castable Urethane 10 min 97 Shore A 19.3 500 – 5 hr demold; 73 N/mm tear strength
ELANTAS AD6407 2K PU Resin – – – – – 100:87.5 mix ratio; thixotropic high-viscosity system
ELANTAS FP-1301 2K PU Sealant 3 min 60 Shore A – 150 – 100:170 by weight; room or heat cure
LOCTITE MR5898 2K Foaming PU ~5 min – – – – Pour-in-place foam; ~2 hr functional cure
LOCTITE PC6231 2K Joint Filler 3 min gel 75–80 Shore A 8.3 82 – 90 min cure; 10–15% joint movement
LOCTITE PC7350 2K PU Repair Compound 7 min gel 87 Shore A 11 275 –29 to 82 2 hr cure; 53 N/mm tear strength
LOCTITE UK1464374 – – – – – – Technical data requires verification
LOCTITE UK2073 2K PU Adhesive System >6 min at 23°C 60–70 Shore A 3.5–4.5 300 – 2:1 with UK2173; low-surface-energy plastics
LOCTITE UK2173 2K PU Adhesive System >6 min at 23°C 60–70 Shore A 3.5–4.5 300 – 2:1 with UK2073; low-surface-energy plastics
LOCTITE UR3371 1K Moisture Cure 40 min skin 50 Shore A >2.5 >300 –30 to 80 High initial tack; non-sag elastic seal
SIKAFLEX 201 1K Moisture Cure ~4 hr 45 Shore A 1.3 550 –40 to 90 Long open time for larger sealing applications
SIKAFLEX 221 1K Moisture Cure 60 min 40 Shore A 1.8 500 –50 to 90 Multipurpose elastic adhesive / sealant
SIKAFLEX 227 1K Moisture Cure 40 min 40 Shore A 1.7 600 –50 to 90 Fast skin; automotive body seam sealing
SIKAFLEX 295UV 1K Moisture Cure 60 min 35 Shore A 2.0 500 –50 to 90 UV resistant; marine plastic glazing

Frequently asked questions

Frequently Asked Questions about Thread Sealants

What is the difference between a THREAD sealant and a threadlocker?

Both may share anaerobic chemistry, but their primary function differs. A thread sealant is formulated to fill the gaps between mating pipe or fitting threads and prevent fluid or gas leakage. A threadlocker is formulated to prevent a fastener from loosening under vibration. A product intended as a thread sealant shouldn't be assumed to match a dedicated threadlocker's locking torque, and vice versa.

How do anaerobic thread sealants cure?

Anaerobic thread sealants remain liquid while exposed to air. Once the sealant is confined between the mating threads of a fitting, oxygen is excluded and trace metal ions on the thread surface trigger the sealant to cure into a rigid, leak-resistant fill within the thread gap.

Why do thread sealants cure slowly on stainless steel or plated fittings?

Anaerobic cure depends on trace metal ions at the thread surface to initiate the reaction. Active metals, such as bare steel and brass, provide enough surface reactivity for a fast, reliable cure. Passive metals, including stainless steel or plated fittings, have surface oxide layers that slow the reaction and can extend cure time significantly. A compatible primer or activator can help restore normal cure speed on passive substrates.

What is the difference between anaerobic thread sealant and PTFE tape?

Anaerobic thread sealants cure into a rigid fill within the thread gap, forming a strong, gap-filling seal well suited to threaded metal pipe connections. PTFE tape and paste are non-curing, relying on compression between the mating threads to form a seal, and are easier to remove for maintenance but generally offer less resistance to vibration loosening. The right choice depends on the joint's pressure, medium, and expected service life.

Can a joint sealed with anaerobic thread sealant be disassembled?

Yes, though it depends on the strength grade used. Lower-strength anaerobic thread sealants typically release with standard hand tools. Higher-strength grades cure into a stronger fill and may require more torque or, in some cases, localized heat to break the joint free without damaging the fitting.

Can any thread sealant be used for gas or oxygen service?

No. Gas, oxygen, and potable-water service typically require a thread sealant with a specific documented approval for that exact use, medium, and pressure and temperature range. A general-purpose thread sealant should not be assumed suitable for these applications without checking the product's specific approval scope.

Learn more

Thread Sealants for Pipe & Fitting Connections

Thread sealants are applied to pipe and fitting threads to fill the microscopic gaps between mating threads, preventing liquids and gases from leaking under pressure. Most thread sealants use anaerobic chemistry, remaining liquid while exposed to air but curing into a rigid, leak-resistant fill once confined between metal threads, where the absence of oxygen and the presence of metal ions trigger polymerization.

Selection depends on the thread material, the medium being sealed, expected pressure and temperature, and whether the joint will need to be serviced. Anaerobic pastes offer strong, gap-filling seals on metal threads, while PTFE tape and paste remain common for lower-pressure or more easily serviced connections.

Thread Sealant Selector Guide

Chemistry and format determine seal strength, pressure tolerance, and serviceability

Anaerobic Thread Sealant
Gap Fill
★★★★★
Pressure Rating
★★★★☆
Vibration Resistance
★★★★★
Serviceability
★★★☆☆
Best for metal pipe threads, hydraulic and pneumatic fittings, higher-pressure joints
PTFE Tape / Paste
Gap Fill
★★★☆☆
Pressure Rating
★★★☆☆
Vibration Resistance
★★☆☆☆
Serviceability
★★★★★
Best for low-pressure connections, frequent maintenance, plastic or mixed-material threads

Key Performance Considerations

Anaerobic Cure Trigger

Stays liquid while exposed to air, but cures once confined between metal threads, excluding oxygen and reacting with surface metal ions.

Active vs Passive Metals

Cures readily on active metals like steel and brass. Passive metals such as stainless steel or plated fittings slow the cure and may need a primer or activator.

Pressure & Medium Rating

Pressure and medium approvals are specific to the tested configuration. A general-purpose sealant shouldn't be assumed rated for every pipe size or fluid.

Gas & Potable-Water Service

Gas, oxygen, and potable-water service require a specific documented approval. Check the product's exact approval scope before use in these applications.

Core Applications

Hydraulic & Pneumatic Systems

Sealing threaded fittings on fluid power lines exposed to pressure and vibration.

Plumbing & Piping

Sealing pipe thread connections in industrial and mechanical piping systems.

Automotive & Machinery

Sealing threaded fittings on fuel, coolant, and lubrication lines subject to vibration.

MRO & Field Maintenance

Resealing or reworking threaded connections on equipment already in service.

Need Help Selecting the Right Thread Sealant?

Thread sealant selection depends on thread material, medium, pressure, and whether the joint needs to be serviced. Our technical team provides product selection support, trial quantity sourcing, and application guidance across anaerobic and PTFE-based thread sealing systems.

Thread Sealant – Quick Reference

AnaerobicCures rigid, strong gap fill, higher pressure
PTFE Tape/PasteNon-curing, easy removal, lower pressure

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