High-strength fasteners — bolts, nuts, washers of strength grades 8.8, 10.9, 12.9 for critical flange, friction-grip (shear-resistant) connections. Grade 8.8: σв = 800 MPa, σт = 640 MPa — standard for automotive, machinery, structural steelwork. Grade 10.9: σв = 1000 MPa — pipeline flanges, bridges, towers. Grade 12.9: σв = 1200 MPa — aviation, power generation, special equipment. Material: alloy steels 40Kh, 30KhGSA, 35Kh. Heat treatment: quenching + tempering. Coating: zinc flake (Geomet, Delta), hot-dip galvanizing, phosphate + oil. GOST R 52644 (flange), DIN 6914/EN 14399. Friction-grip (shear-resistant) connection: bolts tightened with controlled torque (torque wrench or DTI indicator bolts). Load is transferred by friction between parts, not by bolt shear. For bridges, high-rise buildings, seismic zones. Documentation: certificate 3.1 per EN 10204, tensile test report.