LOCTITE® 638 High Strength Retaining Compound

Features and Benefits

Designed for bonding cylindrical fitting parts, particularly with narrow bond gaps up to 0.25mm (0.01"). Great for a fast cure on all metals, including passive substrates like stainless steel.
For a retaining compound offering high strength on all metals, including passive substrates, try LOCTITE® 638. You can expect high temperature performance and good oil tolerance, a fixture time of just four minutes, and gap fill of 0.15 mm to 0.25 mm (0.006" to 0.01"). It even tolerates minor surface contaminants, including industrial oils. A high viscosity product, it’s ideal for shafts, gears, pulleys, and similar cylindrical parts, and can also be used for high strength threadlocking and thread sealing applications. Operating temperature is-55°C to 180°C (-65°F to 355°F). LOCTITE 638 meets the performance requirements of KIWA GASTEC QA AR 214 for admixtures up to and including 100% hydrogen gas on metal threaded fittings – certifications are available in select countries.
  • Ideal for shafts, gears, pulleys and similar cylindrical parts
  • High strength on all metals, including passive substrates (e.g. stainless steel)
  • High temperature resistance
  • Fluorescent under UV for quality control
  • Hydrogen gas approval for sealing threaded metal fittings according to KIWA GASTEC QA AR 214
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Technical Information

Agency approvals / certificates / specifications DVGW (EN 751-1): NG-5146AR0619, NSF P1 Reg. No 123010, WRAS (BS 6920): 0511518
Application method Dispense system, Manual
Applications For close fitting cylindrical parts, For slip fitted parts, Retaining
Color Green
Cure type Anaerobic cure
Fixture time 4.0 min.
Gap fill 0.15 - 0.25 mm
Key characteristics Fluorescent, Oil tolerant, Strength: high strength, Temperature resistant, Viscosity: high viscosity
Operating temperature -55.0 - 180.0 °C (-65.0 - 355.0 °F )
Physical form Liquid
Recommended for use with Metal: steel
Shear strength, Steel 31.0 N/mm² (4500.0 psi )
Viscosity 2500.0 mPa·s (cP)