LOCTITE 518 - Anaerobic Flange Sealant for Aluminum | Henkel
MPN: 518 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $17.2 | $172.00 |
| 100 | $15.8 | $1,580.00 |
| 500 | $14.4 | $7,200.00 |
| 1,000 | $13.1 | $13,100.00 |
Drop-in alternatives for 518 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
54540
β Drop-Inπ Reference alternative (not in catalog)
51817
β Drop-Inπ Reference alternative (not in catalog)
AN 305-73
β Drop-Inπ Reference alternative (not in catalog)
1216
β Drop-Inπ Reference alternative (not in catalog)
A136
β Drop-Inπ Reference alternative (not in catalog)
518 Maximum Ratings & Electrical Characteristics
| Chemical Type | Anaerobic sealant (methacrylate ester) |
| Composition | Single component, urea-free formulation |
| Cure System | Anaerobic (cures in absence of air between metal surfaces) |
| Strength Class | Medium strength |
| Flexibility | Semi-flexible cured film |
| Primer Required | No (primerless on most substrates) |
| Thixotropy | Thixotropic (reduces post-application migration) |
| Substrates | Iron, aluminum, steel (ideal for aluminum) |
| Application Type | Form-in-place gasket on rigid flanged joints |
| Contaminant Tolerance | Cures with minor surface contaminants |
| Standard Package | 300 mL cartridge |
518 300 ml cartridge Pin Configuration Guide
Complete pinout information for 518 (300 ml cartridge package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for 518.
Refer to the datasheet for full pin configuration.
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this digital IC. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
518 is suitable for 6 applications: Pump Housing Sealing, Gearbox and Transmission Covers, Automotive Engine Sealing, Valve and Compressor Flanges, Industrial Machinery Assembly, Maintenance, Repair and Overhaul (MRO).
Pump Housing Sealing
LOCTITE 518 fits pump housing sealing because it cures anaerobically between close-fitting iron, steel, and aluminum flanges and resists low pressures immediately after assembly, per the Henkel datasheet. In centrifugal and gear pumps, the form-in-place bead conforms to machined faces, eliminating cut-gasket compression-set leaks that develop after thermal cycling. The semi-flexible cured film tolerates minor flange movement from bolt loading and temperature swings, while the thixotropic consistency prevents the bead from slumping into the pumped media before assembly. Dispense a continuous bead across the flange land, assemble promptly, and torque fasteners in sequence; the joint can typically be pressure-tested shortly after closure, with full cure in about 24 hours at room temperature.
Recommended
Gearbox and Transmission Covers
Aluminum gearbox and transmission covers are a core application for LOCTITE 518, which Henkel explicitly rates as ideal for aluminum substrates. Cast aluminum housings flex under thermal expansion and bolt clamping; the semi-flexible cured film of 518 accommodates this micro-motion without cracking the seal, a documented advantage over rigid set-in-place gaskets. The anaerobic cure initiates only when air is excluded between the close-fitting faces, giving generous open time for positioning the cover, yet resists low oil pressures immediately after assembly. Clean both machined faces, apply the bead to the cover flange, and install within the skin-over window. Gap should remain small on machined faces for reliable anaerobic cure.
Recommended
Automotive Engine Sealing
In automotive engines, LOCTITE 518 replaces cut paper gaskets on valve covers, timing covers, bearing caps, and oil pump joints where OEM procedures specify form-in-place anaerobic sealing. Its resistance to engine oil and coolant, combined with immediate low-pressure sealing after assembly, makes it suitable for wet fluid passages; a documented field use is sealing bearing caps and valve covers on engines whose service manuals specify 518. The medium cured strength allows future teardown with hand tools, important for serviceable engine assemblies. Apply to one cleaned flange face only, avoid excessive bead width that could squeeze into galleries, and assemble before the product skins over for maximum bond integrity.
Recommended
Valve and Compressor Flanges
LOCTITE 518 seals valve bonnets, compressor housings, and other rigid flanged joints where the parts datasheet lists sealing close-fitting joints between rigid metal faces. Thixotropic rheology keeps the bead on vertical or overhead bonnet faces without sagging before closure, while the anaerobic cure provides immediate resistance to low pressures so pneumatic or hydraulic testing can proceed quickly. The cured film tolerates vibration-induced flange movement common in reciprocating compressors. Surface preparation with a degreaser is recommended; an activator accelerates cure on plated or passivated surfaces. Because it is medium strength, bonnet removal for valve maintenance remains a hand-tool operation rather than a heat-assisted disassembly.
Recommended
Industrial Machinery Assembly
General industrial machine building uses LOCTITE 518 across gearbox splits, bearing housings, and machined covers to standardize fluid-tight joints and eliminate cut-gasket inventory. Henkel positions 518 as the general-purpose, primerless grade for rigid iron, aluminum, and steel flanges, making it the default choice when substrate varies across a machine. Its tolerance of minor surface contaminants improves first-pass yield in real production conditions where perfect cleanliness is impractical. Immediate low-pressure sealing shortens assembly-line leak-test dwell. Standardize application with automated bead dispensing for consistent width, and train assembly staff to close joints within the open time to preserve full anaerobic cure performance.
Recommended
Maintenance, Repair and Overhaul (MRO)
For MRO shops, LOCTITE 518 replaces perished cut gaskets during resealing of pumps, gearboxes, and engine cases without waiting for gasket spares, since the form-in-place bead is cut on demand. The medium-strength cured film permits hand-tool disassembly at the next service, and residue removal is straightforward with scraping plus solvent. Because it cures even with minor surface contamination, field resealing is tolerant of imperfect workshop conditions. The 300 mL cartridge supports many small repairs per unit. For temperature-critical joints, verify service temperature against the manufacturer datasheet before substituting for high-temperature silicone grades, and allow full cure before returning equipment to pressurized service.
Recommended
Recommended Products Summary
Engineering reference data for 518 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | 54540 | 51817 | AN 305-73 | 1216 | A136 |
|---|---|---|---|---|---|---|
| Package | 300 mL cartridge | Cartridge | Cartridge | Cartridge | Cartridge | Cartridge |
| Brand | Henkel (LOCTITE) | Permatex | Permatex | Weicon | ThreeBond | Permabond |
| Sealant Type | Anaerobic, form-in-place | Anaerobic gasket maker | Anaerobic gasket maker | Anaerobic flange sealant | Anaerobic flange sealant | Anaerobic sealant |
| Strength Class | Medium | Medium | Medium | Medium | Medium | Medium |
| Max Service Temperature | [DATA_NEEDED: service temperature range] | 150 C | [DATA_NEEDED] | 150 C | 150 C | 150 C |
| Max Flange Gap | [DATA_NEEDED: maximum gap fill] | 0.25 mm | [DATA_NEEDED] | 0.25 mm | 0.25 mm | 0.25 mm |
| Primer Required | No (primerless) | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Primary Substrates | Iron, aluminum, steel | Machined metal flanges | Machined metal flanges | Machined metal flanges | Machined metal flanges | Machined metal flanges |
Key Differentiators
- Primerless cure on active metals (vs 1216)
- Aluminum-optimized semi-flexible film (vs 515)
- Immediate low-pressure sealing (vs 54540)
Design Notes
Anaerobic cure requires metal-to-metal contact at a small gap. Estimated: the cross-reference literature places the reliable anaerobic cure envelope at machined flange gaps up to 0.25 mm; gaps beyond this slow or prevent full cure. Do not use 518 on plastic, coated, or heavily rough-cast surfaces without an activator, and do not fill large chips or machining voids with sealant - those are gasket or repair-compound applications, not form-in-place anaerobic joints.
Flange preparation drives seal reliability. Degrease both mating faces with a solvent cleaner such as Loctite SF 7611 and remove old gasket residue. Apply a single continuous bead centered on the bolt-hole land, never across bolt holes themselves. Assemble parts within the open time (a few minutes at room temperature) before the bead skins over; skinning prevents the faces from wetting and completing the anaerobic cure. Torque fasteners in the specified crosswise sequence.
For service readiness, plan around two time constants: immediate handling strength and full cure. Per the Henkel datasheet, 518 resists low pressures immediately after flange assembly, so light leak testing can follow promptly. Full chemical and pressure resistance develops over roughly 24 hours at room temperature (confirm the exact value in the curing-performance table). Cold workshops and inactive substrates extend these times; use an activator such as LOCTITE 7649 to accelerate cure where required.
Compliance Information
This is a chemical sealant product, not an electronic component; RoHS/AEC-Q100 are not applicable. REACH status per Henkel SDS: unknown from provided data.
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