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. Features: 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