Loctite 5910: Silicone Flange Gasket (FIPG) in Detail
Loctite SI 5910 is a black, low-strength RTV silicone gasket material for flexible flange connections. As a FIPG product (Formed-In-Place Gasket), the seal is applied directly to the flange and replaces preformed flat gaskets. The 5910 is particularly suitable for applications requiring flexible sealing at temperatures up to 200 °C, with short-term peaks up to 260 °C.
Technical Data
| Property | Value |
|---|---|
| Product type | RTV silicone gasket material (oxime cross-linking) |
| Application | FIPG: Formed-In-Place-Gasket |
| Color | Black |
| Consistency | Thixotropic paste (non-slumping) |
| Density | 1.34 g/cm³ at 20 °C |
| Shore hardness (cured) | 30 Shore A |
| Tensile Strength | ≥1.7 N/mm² (ISO 37) |
| Tensile strength at 100% elongation | 0.6 to 1.0 N/mm² |
| Elongation at break | ≥400% (ISO 37) |
| Shear strength | 0.9 to 1.4 N/mm² (130 to 200 psi) |
| Gap bridging | Up to 1 mm |
| Temperature range | -55 °C to +200 °C (continuous operation) |
| Short-term | Up to +260 °C |
| Tack-free time | ≤40 minutes (at 25 °C, 50 % r.h.) |
| Full cure | 24 hours at 23 °C / 50 % relative humidity. |
| Cure depth after 24 h | ~3 mm |
Crosslinking mechanism
Loctite 5910 is an oxime-curing (neutral-curing) RTV-1 silicone. Curing begins at the surface through contact with atmospheric moisture and progresses from the outside inward.
Why oxime crosslinking?
- Odorless: Unlike acetate silicones (vinegar smell), oxime silicone does not release acetic acid
- Corrosion-free: No aggressive cleavage products, safe on copper, brass, and other sensitive metals
- Sensor compatible: No acetic acid that could attack electronic components or sensors
Curing profile:
- Tack-free time: ≤40 minutes (at 25 °C, 50 % r.h.)
- Handling strength: ~4 hours
- Functional sealing: ~24 hours
- Full curing: 24 to 72 hours (depending on gap depth and humidity)
Applications
Automotive: Engine gaskets
Loctite 5910 was primarily developed for flexible flange gaskets in the automotive sector:
- Oil pan: FIPG seal between engine block and oil pan (flexible flange movement due to vibrations)
- Timing Chain Cover: Seal at the timing cover with temperature fluctuations
- Valve Cover: Flexible sealing for aluminum- or plastic-based valve covers
- Transmission housing: Flexible flange seal for automatic and manual transmissions
- Crankcase Halves: Sealing of the engine housing parting line
Not suitable for: Water pumps and water-carrying applications. The 5910 is optimized for permanent oil contact , not for coolants or water. For water pumps, we recommend Loctite 5699 or 5920.
Industrial applications
- Housing sealing for compressors and pumps
- Flange seal for piping systems (non-aggressive media)
- Sealing of inspection covers and maintenance openings
- Flexible seals in the food industry (where approved)
Suitable Substrates
| Substrate | Adhesion | Note |
|---|---|---|
| Steel, Stainless Steel | Very good | Clean and degrease the surface |
| Aluminum | Very good | No primer required |
| Cast iron | Good | Roughen the surface on porous areas |
| Copper, brass | Good | Oxime crosslinking: corrosion-free |
| Plastic (PA, PBT) | Good | Check material compatibility |
| Glass | Good | - |
Processing: Step by Step
1. Surface Preparation
- Completely remove old sealant residue (mechanically or with Loctite SF 7200 Gasket Remover)
- Clean and degrease flange surfaces with isopropanol or Loctite SF 7063
- Surfaces must be dry and dust-free
2. Application
- Apply the sealant evenly as a bead (2 to 3 mm diameter) onto one flange half
- Route the bead around all bolt holes (not through the holes)
- For large flange surfaces, apply in a flat spiral pattern
- Gap dimension: ideally 0.1 to 0.5 mm, maximum 1 mm
3. Assembly
- Assemble flange halves promptly after application (tack-free time ≤40 min, ideally within 10 min)
- Tighten screws by hand, do not fully load
- Remove excess sealant
4. Curing and commissioning
- After 4 hours: tighten bolts to specified torque
- After 24 hours: functional test possible
- Only subject to operating fluids after 24 hours
Loctite 5910 vs. other Loctite flange sealants
| Property | 5910 | 5699 | 5920 | 5970 |
|---|---|---|---|---|
| Color | Black | Grey | Copper | Black |
| Strength | Low | Low | Medium | High |
| Temperature range | -55 to +200 °C | -55 to +200 °C | -55 to +350 °C | -50 to +200 °C |
| Tensile Strength | 1.2 N/mm² | 1.7 N/mm² | 1.4 N/mm² | 1.5 N/mm² |
| Flexibility | High (≥400 %) | Medium | Medium | Low |
| Gap bridging | Up to 1 mm | Up to 1 mm | Up to 0.5 mm | Up to 0.25 mm |
| Curing type | Oxime | Oxime | Oxime | Acetate |
| Main application | Flexible flanges, oil | Universal, low odor | High temp. up to 350 °C | High vibration/torque |
Which type when?
- Loctite 5910: Flexible flanges with oil contact (oil pan, valve cover, gearbox housing). Not for water-carrying applications.
- Loctite 5699: Universal flange sealant, low odor, highest tensile strength (1.7 N/mm²)
- Loctite 5920: High temperature up to +350 °C: Exhaust manifolds, turbocharger housings, exhaust side
- Loctite 5970: High vibration and torque load, rigid flanges
Frequently Asked Questions (FAQ)
Can Loctite 5910 completely replace a flat gasket?
Yes, for flexible flange connections with a maximum gap of 1 mm. The 5910 is specifically designed as a FIPG product to replace preformed gaskets. For rigid flange connections under high mechanical stress, we recommend Loctite 5970.
How do I remove old Loctite 5910?
Mechanically with a plastic scraper or gasket remover (Loctite SF 7200). The cured silicone can usually be peeled off as a continuous band. Remove residues with isopropanol.
How quickly can I start the engine after sealing?
At the earliest after 24 hours at room temperature. The silicone requires this time to cure sufficiently and become pressure-tight. Premature loading can damage the seal.
Is Loctite 5910 oil-resistant?
Yes. The 5910 is resistant to engine oil, transmission oil, coolant (glycol), and fuels. It is specifically formulated for automotive applications.
What is the difference between Loctite 5910 and Loctite 518?
Loctite 518 is an anaerobic flange sealant (cures without air between metal surfaces). Loctite 5910 is a silicone (cures through air humidity). The 518 offers higher strength on rigid flange connections, the 5910 higher flexibility and temperature resistance.
Further information
- Permabond Adhesives: Range, Technical Data & Loctite Comparison
- Bonding metal without welding: 5 high-performance adhesives compared
- Loctite 638: High-Strength Shaft-Hub Connection
- Selecting and correctly applying threadlockers
- Industrial adhesives compared: epoxy, cyanoacrylate, anaerobic, UV, MMA. Which adhesive for which application?
- RTV-1 Silicones & Sealants in the Shop
- Request Technical Consultation
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