Product details
| Grade | Loctite SI 5927 |
| Strength | Flexible silicone |
| Colour | Red |
| Family | Flange & gasket sealants |
| Brand | Loctite (Henkel) |
| Stock | Held in Dubai — buy one or bulk |
Pack sizes
| Pack | Format |
|---|
| 300 ml | cartridge |
Prices on request. Tell us the quantity you need.
Check stockWhat Loctite SI 5927 is for
This is a silicone, not an anaerobic — a genuinely different product from the rest of this family, and it is not interchangeable with them. It cures on moisture in the air rather than in the absence of it, stays flexible at 36 Shore A with 330% elongation, and is used to 315°C. That combination makes it the grade for joints that move or run very hot: valve and rocker covers, oil pans, water pumps, intake manifolds, and industrial furnaces, ovens, boilers and exhaust ducting.
Key features
- Silicone (RTV) — cures on atmospheric moisture, not in its absence
- Flexible: 36 Shore A, 330% elongation — absorbs shock and flange movement
- Typically used to 315°C, far beyond any anaerobic in this family
- Formulated for the low silicone-volatile requirements of automotive 315°C flange sealants
- Tack free in 1 hour, full cure in 24 hours
- Also a gasket dressing for pre-cut gaskets
- Excess wipes off with a non-polar solvent before cure
Typical applications
- Flexible flanges
- Vibration joints
Technical data
Uncured material
| Technology | Silicone |
| Chemical type | Acetoxy silicone |
| Appearance | Red homogeneous paste |
| Components | One component — no mixing |
| Cure | Room temperature vulcanising (RTV) — moisture cure |
| Consistency | Thixotropic — reduced migration after application |
| Odour | Acetic acid |
| Specific gravity at 25°C | 1.05 |
Cure and cured properties
Cured 7 days at 25°C and 50% RH. Cure times vary with temperature, humidity and gap.
| Tack free | 1 hour |
| Full cure | 24 hours |
| Shore hardness (ISO 868, Durometer A) | 36 |
| Elongation (ISO 37) | 330% |
| Tensile strength (ISO 37) | 0.7 N/mm² (100 psi) |
| Service temperature | Typically used to 315°C |
Heat ageing at 204°C
It softens and becomes more elastic — for flange sealing this is usually an advantage.
| Exposure | Shore A | Tensile N/mm² | Elongation |
|---|
| 1 week | 29 | 0.7 | 370% |
| 2 weeks | 28 | 0.7 | 450% |
| 4 weeks | 25 | 0.7 | 490% |
| 8 weeks | 22 | 0.6 | 500% |
Heat ageing at 260°C and 316°C
At 260°C softening is reversion and happens however the sealant is cured. At 315°C the polymer rearranges and oxidises, so it hardens instead — oxidation is retarded when it is used as a flange sealant.
| Exposure | Shore A | Tensile N/mm² | Elongation |
|---|
| 1 week at 260°C | 23 | 0.4 | 520% |
| 4 weeks at 260°C | 15 | 0.1 | 280% |
| 1 week at 316°C | 48 | 0.6 | 175% |
| 3 weeks at 316°C | 82 | 0.5 | 25% |
How to use it
- Flange faces must be clean and free from grease.
- Moisture cure begins the moment it is dispensed — mate the parts within a few minutes.
- Press or clamp the parts firmly together. Do not slide them together.
- Full performance develops over 24 hours.
- Excess uncured material wipes away with a non-polar solvent.
- Excess cured material comes off with a knife or a single-edge blade.
Handling and storage
- Do not use for gasketing carburettors or fuel control devices where it will be in constant contact with hydrocarbon fuels — it swells excessively and loses its mechanical properties.
- Not recommended for pure oxygen or oxygen-rich systems.
- Not a sealant for chlorine or other strong oxidising materials.
- 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.
Silicone or anaerobic — which flange sealant?
The anaerobics in this family (510, 515, 518, 573, 574) cure in the absence of air between close-fitting rigid metal faces, hold gaps to 0.25 mm, and give a hard, load-bearing joint. SI 5927 cures on atmospheric moisture, stays soft and elastic, and tolerates movement and much higher temperatures. Rigid machined flange, tight gap → anaerobic. Flange that flexes, an uneven face, or service above 200°C → SI 5927. It is not a drop-in substitute in either direction.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
