Thread Sealants
Gap Filling & Lubricating
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.
-
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
- 2 weeks
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
★★★★★
★★★★☆
★★★★★
★★★☆☆
★★★☆☆
★★★☆☆
★★☆☆☆
★★★★★
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