Product details
| Grade | Loctite 573 |
| Strength | Low strength |
| Colour | Green |
| Family | Flange & gasket sealants |
| Brand | Loctite (Henkel) |
| Stock | Held in Dubai — buy one or bulk |
Pack sizes
Prices on request. Tell us the quantity you need.
Check stockWhat Loctite 573 is for
The slow-cure form-in-place gasket, and the one to use when assembly takes time. On a large flange — a gearbox cover, an engine casing — a fast-curing sealant can begin to set before every bolt is located. 573 cures deliberately slowly, so the joint can still be adjusted, and it is low strength at ≥1.5 N/mm² so the flange comes apart again without a fight.
Key features
- Slow cure — long open time for large or awkward flanges
- Low strength: ≥1.5 N/mm² compressive shear, easy disassembly
- Thixotropic green paste — will not migrate after application
- Gaps to 0.25 mm
- 100% of initial strength retained in motor oil at 125°C and water/glycol at 87°C
- Heat ageing data published to 150°C
Typical applications
- Flange faces
- Slow assembly
Technical data
Uncured material
| Technology | Acrylic |
| Chemical type | Dimethacrylate ester |
| Appearance | Green paste |
| Fluorescence | Positive under UV light |
| Components | One component — no mixing |
| Cure | Anaerobic; secondary cure by activator |
| Viscosity, Brookfield RVT 25°C | Spindle 6 at 20 rpm: 13,500–33,000 mPa·s |
| Viscosity at 2.5 rpm | ≥38,000 mPa·s |
| Viscosity class | Medium, thixotropic |
| Specific gravity at 25°C | 1.25 |
Strength
Cured at 22°C.
| Compressive shear strength, 24 h (ISO 10123) | ≥1.5 N/mm² (≥217 psi) |
| Lap shear strength, 72 h, grit-blasted steel | 1.3 N/mm² (190 psi) |
| Tensile strength, grit-blasted steel (ISO 6922) | 5 N/mm² (725 psi) |
| Maximum gap | 0.25 mm |
Chemical resistance
Effect of environment on strength, not a measure of sealing performance.
| Environment | °C | 100 h | 500 h | 1,000 h |
|---|
| Motor oil | 125 | 100% | 100% | 100% |
| Water / glycol 50:50 | 87 | 100% | 100% | 100% |
| Petrol | 22 | 100% | 70% | 70% |
Cured material
| Coefficient of thermal expansion (ISO 11359-2) | 80 × 10⁻⁶ K⁻¹ |
| Thermal conductivity (ISO 8302) | 0.1 W/(m·K) |
| Specific heat | 0.3 kJ/(kg·K) |
| Heat ageing data published to | 150°C |
| Cures down to | 4°C |
How to use it
- Flange faces must be clean and free from grease.
- Designed for close-fitting flanged parts with gaps up to 0.25 mm.
- Apply as a continuous bead, a rolled film, or by screen printing to one flange face.
- For gaps over 0.125 mm using a pen roller, apply a rolled film to both faces.
- Low pressure may be applied to confirm the seal immediately after assembly, before curing.
- Tighten the flanges as soon as possible after assembly to avoid shimming.
Handling and storage
- Not recommended for pure oxygen or oxygen-rich systems.
- Not a sealant for chlorine or other strong oxidising materials.
- Not normally recommended on plastics — thermoplastics can stress-crack.
- Check compatibility if aqueous washing systems are used before bonding; some washes affect the cure.
- Store unopened and dry, ideally 8°C to 21°C; outside 8–28°C the properties can be affected.
- Do not return decanted product to the original container.
Loctite 573 or 574?
Both are anaerobic form-in-place gaskets for rigid metal flanges with gaps to 0.25 mm. The difference is cure speed and strength. 573 cures slowly and stays low strength (≥1.5 N/mm²) — right for large flanges that take time to assemble and must come apart easily. 574 is faster and stronger (≥6.0 N/mm²) — right for production work or a joint that should stay put. For higher strength again, or petrol resistance, neither is ideal: see 518.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
