Loctite SI 5900 Flange Sealant 300ml
Available
Loctite SI 5900 is a one-component, black, thixotropic oxime silicone flange sealant. It cures at room temperature with moisture from the air (RTV).
Henkel lists it for gasketing, for example stamped sheet metal covers such as timing covers and oil sumps, and describes excellent resistance to automotive engine oils. In Henkel's blow-out test (0.014 MPa, 4 mm flange, 1.5 mm gap) it holds for 100 s or more.
Where this product is used
- Stamped sheet metal covers such as timing covers
- Oil sumps
- Gaskets in contact with automotive engine oils
Features
- One component, no mixing
- Black, thixotropic paste
- Oxime silicone, room temperature moisture cure (RTV)
- Tack-free in 7 to 24 minutes at 25 °C and 50 % RH
- Excellent resistance to automotive engine oils
- Blow-out resistance of 100 s or more (4 mm flange, 1.5 mm gap, 0.014 MPa)
- Cured elongation of at least 400 %, Shore A hardness 31 to 46
Key specifications
| Specification | Detail |
|---|---|
| Chemical type | Oxime silicone |
| Colour | Black paste (uncured), thixotropic |
| Cure | One component, room temperature vulcanising (RTV), moisture cure |
| Specific gravity (25 °C) | 1.30 to 1.37 |
| Extrusion rate (Semco cartridge, 0.62 MPa, 15 s, 25 °C) | 20 to 50 g/min |
| Tack-free time (25 °C, 50 % RH) | 7 to 24 minutes |
| Blow-out resistance (4 mm flange, 1.5 mm gap, 0.014 MPa) | 100 s or more |
| Hardness, Durometer A (ISO 868, 1 week at 25 °C, 50 % RH) | 31 to 46 |
| Elongation (ISO 37, 1 week at 25 °C, 50 % RH) | At least 400 % |
| Tensile strength (ISO 37, 1 week at 25 °C, 50 % RH) | At least 1.7 N/mm² |
| Lap shear on mild steel (ISO 4587, 21 days at 23 °C, 50 % RH, 0.5 mm gap) | 1 to 1.4 N/mm² |
| Approvals | NSF International registered to NSF Category P1, a sealant where there is no possibility of food contact in and around food processing areas (regional approval; contact the local Henkel Technical Service Centre) |
| Storage | 8 °C to 21 °C, unopened, dry |
| Technical data sheet | Henkel TDS October 2018 |
Selecting the right option
For other one-component silicone gasket makers in the Loctite range see Loctite SI 587 Blue High Performance RTV Silicone Gasket Maker 95g and Loctite SI 5699 Grey RTV Silicone Gasket Maker. Compare the data sheets for the flange type, fluids and temperatures in your application.
Using it
Use clean, grease-free surfaces. Mate the parts within a few minutes of dispensing, because the moisture cure starts as soon as the sealant is exposed to air.
Allow the sealant to cure (for example seven days) before heavy service loads. Excess can be wiped off with non-polar solvents.
Storage and handling
Store unopened in a dry location, ideally between 8 °C and 21 °C. Storage below 8 °C or above 28 °C can adversely affect the properties of the product.
Limits and safety
Not recommended for pure oxygen or oxygen-rich systems, or as a sealant for chlorine or other strong oxidising materials. Lap shear strength is low (0.7 to 2 N/mm² on the metals tested), so treat it as a sealant, not a structural adhesive. Read the safety data sheet before use.
Frequently asked questions
How long does Loctite SI 5900 take to skin over?
Tack-free time is 7 to 24 minutes at 25 °C and 50 % relative humidity. Mate the parts within a few minutes of dispensing.
How long before Loctite SI 5900 can take heavy loads?
Henkel suggests allowing about seven days before heavy service loads.
Does Loctite SI 5900 resist engine oil?
Yes. Henkel describes excellent resistance to automotive engine oils.
Is Loctite SI 5900 food-grade?
No. It is registered to NSF Category P1, for use where there is no possibility of food contact in and around food processing areas. Henkel notes this is a regional approval.
What gap can Loctite SI 5900 fill?
The Henkel data sheet gives no gap-fill figure. Its 0.5 mm and 1.5 mm gaps are test conditions only, so contact AIMS if you need advice on a large gap.
What temperature can Loctite SI 5900 take?
The data sheet states no operating temperature range. In Henkel's heat ageing tests, tensile strength after 1000 h at 200 °C was 1.3 N/mm² with 220 % elongation.
Related products
See also: Loctite SI 587 Blue High Performance RTV Silicone Gasket Maker 95g, Loctite SI 5699 Grey RTV Silicone Gasket Maker, Loctite 598 Black RTV Silicone Gasket Maker 95g, Loctite 587 Blue Maxx Silicone Flange Sealant 300ml, Loctite 5920 Copper Maxx Silicone 85g.
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