Features and Benefits

Available in:

  • 250.0 ml bottle


  • 50.0 ml bottle


  • 10.0 ml bottle


Retaining Compound - high strength. General purpose. Fast curing.
LOCTITE® 638 is designed for the bonding of cylindrical fitting parts, particularly where bond gaps can approach 0.25 mm. The product cures when confined in the absence of air between close-fitting metal surfaces and prevents loosening and leakage due to shock and vibration. It not only works on active metals but also on passive substrates, exhibiting robust cure performance. The product offers high-temperature performance and good oil tolerance, and tolerates minor surface contaminants.
  • High temperature resistance
  • Tolerates minor contaminants, including industrial oils
  • High strength on all metals, including passive substrates (e.g. stainless steel)
  • Ideal for shafts, gears, pulleys and similar cylindrical parts
  • P1 NSF Reg. No.: 123010
  • DVGW Approval (EN 751-1): NG-5146AR0619
  • WRAS Approval (BS 6920): 0511518
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Technical Information

Agency Approvals / Specifications DVGW (EN 751-1): NG-5146AR0619, NSF P1 Reg No: 123010, WRAS (BS 6920): 0511518
Color Green
Diametrical Clearance (Maximum) 0.25 mm
Fixture Time 4 min.
Fixture Time Temperature 39 °F
Full Cure Temperature 77 °F
Gap Fill 0.01 in.
Shear Strength Unit, Steel psi
Shear Strength, Steel 4500
Specific Gravity 1.09 g/l
Specific Gravity Temperature 25 °C
Substrates Metal: Steel
Temperature -65 - 300 °F
Viscosity 2500 mPa.s (cP) Brookfield
Viscosity Temperature 77 °F