Loctite 577

LOCTITE 577 is an anaerobic acrylic based thread sealant supplied as a single component high viscosity yellow paste that requires no mixing before application. The product cures in the absence of air when confined between closely fitting metal threaded components and provides medium strength locking and sealing performance. It is particularly suitable for stainless steel and other passive substrates without requiring pre-activation, while also performing effectively on active metals such as brass and copper. The thixotropic nature of the material minimizes migration after application and allows controlled dispensing on vertical or overhead surfaces. The product is capable of sealing thread gaps up to approximately 0.25 mm and maintains curing performance even in the presence of minor contamination from cutting oils, lubricants, corrosion protection fluids and surfactant containing cleaners. The material is registered for use in specific industrial environments including applications where there is no possibility of food contact in food processing areas. It conforms to recognized European standards for sealing metallic threaded joints in contact with gases and hot water and carries certification for gas applications. It is approved for certain gas installations with working pressures up to 2000 kPa and operating temperatures from approximately −10°C to 135°C. The product has also been evaluated and certified for hydrogen service according to established approval requirements. The uncured product has a specific gravity of approximately 1.1 at 25°C. Brookfield viscosity measured at 25°C using spindle 6 is approximately 100,000 mPa·s at 2.5 rpm and about 24,500 mPa·s at 20 rpm, confirming its high viscosity thixotropic behavior. Cure speed depends on substrate type, temperature, bond gap and the use of activators. Elevated temperatures accelerate strength development, while lower temperatures slow curing. For inactive metals or when rapid strength build up is required, activators such as SF 7471, SF 7649 or SF 7091 may be used. After 24 hours curing at 22°C, breakaway torque values vary depending on fastener material and size. Typical values include approximately 33 N·m for M10 steel assemblies, 23 N·m for brass, 20 N·m for zinc dichromate, 15 N·m for stainless steel and 30 N·m for zinc phosphate fasteners. Smaller M6 fasteners show around 7 N·m and larger M16 fasteners approximately 69 N·m. Prevail torque values are lower but demonstrate consistent locking characteristics across different substrates. Breakloose torque on M10 steel fasteners pre-torqued to 5 N·m is approximately 27 N·m, and after one week cure at 22°C on zinc phosphate assemblies it reaches approximately 30 N·m. Compressive shear strength on steel pins and collars is about 5 N/mm². The cured material has a specific heat of approximately 2.0 kJ/(kg·K), tensile strength around 1.3 N/mm² according to ISO 37, and tensile modulus approximately 168 N/mm². The product has been evaluated for hot strength and maintains functionality at low temperatures down to −75°C. Heat aging tests at elevated temperatures show gradual changes in strength depending on exposure duration. Chemical resistance testing demonstrates good retention of strength after exposure to acetone, diesel exhaust fluid, brake fluid, ethanol, motor oil at elevated temperature, unleaded petrol, water/glycol mixtures, biodiesel and E85 fuel, with percentage strength retention varying according to environment and exposure time. For assembly, threaded components should be cleaned and dried before application. A continuous 360 degree bead should be applied to the leading threads of the male fitting, leaving the first thread free to reduce excess squeeze out. The material should be pressed into the threads to ensure complete void filling. For larger threads, additional product may be applied to female threads if required. Fittings should be assembled and tightened according to manufacturer recommendations. Properly tightened assemblies will seal immediately against moderate pressures, while maximum pressure and chemical resistance are achieved after a minimum curing time of 24 hours. Excess uncured material may be removed with an appropriate cleaning solvent. For disassembly, standard hand tools are normally sufficient. For large diameters or long engagement lengths exceeding approximately one inch, localized heating to about 250°C may be required prior to removal. Cured material can be cleaned using solvent soaking combined with mechanical methods such as wire brushing. The product is not recommended for use in pure oxygen or oxygen enriched systems and should not be selected as a sealant for chlorine or other strong oxidizing agents. It is generally not recommended for thermoplastic materials unless compatibility has been verified. Recommended storage temperature is between 8°C and 21°C in the original unopened container. Storage below 8°C or above 28°C may adversely affect product properties. The technical values provided represent typical performance data and users should conduct application specific validation testing before production use.