Overview
Loctite 55 is a multi-filament thread sealing cord designed specifically for pipe threads. Instead of wrapping thin PTFE tape or working with messy pastes, installers simply wind the cord directly into the threads and assemble the joint.
Once the fitting is tightened, Loctite 55:
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Forms a dense, flexible seal in the thread flanks
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Helps prevent leaks of water, gas and other compatible fluids
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Provides lubrication during assembly, giving smoother tightening
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Maintains a seal even under vibration, pressure pulses and thermal cycling
Because the cord fills the thread space rather than relying on surface coverage, it delivers consistent, repeatable sealing performance across a wide range of pipe sizes.
Why choose Loctite 55?
1) Instant sealing – no cure time
Unlike anaerobic liquid sealants that must cure, Loctite 55 seals immediately on assembly. In many applications, the system can be pressure-tested or put into service straight away, saving time on site.
2) Adjustable joints
Loctite 55 creates a forgiving, elastic seal in the threads. In most cases, the fitter can back off the joint slightly to orient elbows, tees or gauges without losing sealing integrity, which is much harder to do with tape.
3) Works on metal and plastic
The cord is suitable for metal and many plastic pipe threads (e.g. brass, steel, certain plastic fittings), allowing one product to cover a large portion of typical plumbing and plant maintenance work. Always check compatibility for your specific plastic.
4) Clean, simple, low-waste
There are no shredded tape strings, no sticky pastes, and less chance of debris entering valves or filters. The integrated dispenser protects the cord, reduces waste and fits neatly into a toolbox or pocket.
5) Consistent sealing performance
Because you apply a defined number of wraps based on pipe size, Loctite 55 helps standardize installation practice. This improves consistency between different installers and reduces rework from under- or over-wrapped tape.
Typical Applications
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Domestic and commercial plumbing
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Hot and cold water lines
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Heating and cooling systems
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Sanitary and utility pipework
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Industrial and plant utilities
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Compressed air and inert gas lines
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Cooling water, service water and general utility circuits
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Equipment hook-ups for pumps, compressors, dryers and filters
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Maintenance, repair & overhaul (MRO)
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Quick, clean sealing of replacement valves, gauges and fittings
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On-site service work where downtime must be kept to a minimum
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Loctite 55 is intended for threaded pipe connections and should not be used on pure oxygen service, strong oxidizing media, or where local regulations demand specific approved products. Always check local approvals and compatibility.
How to Use Loctite 55
Step 1 – Prepare the threads
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Make sure threads are machined correctly and undamaged.
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Remove loose dirt, rust, old tape and sealing materials.
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Wipe off heavy oil or grease; lightly oiled metal threads are usually acceptable, but cleaner is always better.
Step 2 – Anchor the cord
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Pull out a short length of Loctite 55 from the dispenser.
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Anchor the end of the cord in the first thread on the male fitting, holding it firmly with your thumb.
Step 3 – Wind the cord
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Wind the cord in the direction of tightening, keeping each wrap snug in the thread root.
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Overlap slightly as you work towards the back of the thread.
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Use the recommended number of wraps for the pipe size (small diameters need fewer wraps, large diameters more).
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Cut or break off the cord and smooth the end into the threads.
Step 4 – Assemble the joint
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Screw the male and female parts together.
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Tighten to the normal torque for that connection type.
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If necessary, back off slightly to achieve the correct orientation for elbows, tees or instrument connections – in most cases, the seal remains intact.
Step 5 – Test and put into service
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In many standard applications, Loctite 55 provides instant sealing and allows immediate pressure testing.
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For critical or high-pressure systems, follow your site procedures and any additional guidelines in the technical literature.
Step 6 – Disassembly
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When maintenance is required, unscrew the joint with normal pipe tools.
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Remove any remaining cord from the threads before reassembly.
Safety & Handling
As with any professional sealing product, basic safety precautions apply:
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Avoid direct and prolonged skin contact; may cause irritation in sensitive individuals.
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Prevent contact with eyes; rinse thoroughly with clean water if contamination occurs.
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Use in well-ventilated areas, particularly in confined spaces.
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Do not allow product residues to enter drains or natural waterways.
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Store in the original dispenser, closed when not in use, in a cool, dry place away from direct heat and sunlight.
Always follow the instructions and recommendations given in the latest Safety Data Sheet (SDS) for Loctite 55 in your region.
FAQs
Q1: What is the main difference between Loctite 55 and PTFE tape?
Loctite 55 is a sealing cord, not a flat tape. It packs more uniformly into the thread roots, doesn’t shred, and provides instant, reliable sealing with less risk of loose fragments entering the system.
Q2: Can Loctite 55 be used on both metal and plastic threads?
Yes, Loctite 55 is designed for metal and many plastic fittings. However, you should always check compatibility with the specific plastic material and follow any local approval requirements.
Q3: Does Loctite 55 need curing time before pressure testing?
In most standard water and utility gas applications, Loctite 55 gives an instant seal on assembly, so you can usually pressure-test straight away. For demanding or high-pressure systems, follow your internal procedures and the latest technical guidance.
Q4: Can I reposition a fitting after I’ve tightened it?
Yes. One of the big advantages of Loctite 55 is that you can normally back off the joint slightly to re-align elbows, tees and gauges without losing sealing performance, as long as you do not completely undo the connection.
Q5: Is Loctite 55 suitable for drinking water and gas?
Loctite 55 is widely used in potable water and gas installations where it is approved by local or regional authorities. Always check the approval list and local regulations for your country before use in regulated services.
Q6: How many wraps of Loctite 55 do I need?
The required amount depends on pipe size and thread pitch. As a rule of thumb, smaller diameters need fewer wraps, larger diameters more. Follow the usage instructions on the dispenser or your internal standard work instructions.
Q7: Can Loctite 55 be used together with other sealants or PTFE tape?
No. Loctite 55 is designed to be a standalone sealing solution. Combining it with other tapes or pastes can interfere with correct seating of the threads and make performance less predictable.
