PTFE Coated ASTM 3 B7 Thread Rod 2H Nut

A: For diameters up to 2-1/2 inches (64 mm), ASTM A193 Grade B7 requires minimum tensile strength of 125 ksi (860 MPa) and minimum yield strength of 105 ksi (724 MPa), with minimum elongation of 16% and reduction of area of 50%, and a maximum hardness of 321 HBW (35 HRC). For diameters larger than 2-1/2 inches up to 4 inches, tensile strength reduces to 115 ksi (793 MPa) with yield of 95 ksi (655 MPa). The material is heat-treated by quenching in a liquid medium followed by tempering at a minimum of 1100°F (593°C). Maximum continuous service temperature for Grade B7 is 450°C (842°F).

A: The PTFE (Xylan 1424) coating thickness typically ranges from 15–35 microns, with a coefficient of friction of 0.055–0.10 per ASTM D1894. The coating reduces the nut factor (K) to approximately 0.12, compared to 0.20 for plain dry steel and 0.15 for lubricated steel, enabling make-up torque reduction of up to 70% and consistent torque-tension relationships for preload control. Service temperature range for the PTFE coating is -50°C to +210°C, with salt spray resistance per ASTM B117 exceeding 1,000 hours to first red rust. The coating provides chemical inertness and prevents thread galling during installation and disassembly.

A: The threaded rod must be paired with ASTM A194 Grade 2H heavy hex nuts, which are quenched and tempered carbon steel nuts with a proof load stress of 175,000 psi minimum and hardness range of 24–35 HRC—the industry standard mating nut for B7 studs in pressure-containing bolting applications. Each threaded rod 3/8 inch diameter and larger requires the grade symbol "B7" and the manufacturer's identification mark stamped on one end. Heat code (traceability number) is also required, linking each fastener to its specific Mill Test Report (MTR) for full material traceability. For PTFE-coated assemblies, the coating is applied after heat treatment and thread rolling, and the assembly can be supplied with EN 10204 Type 3.1 inspection certificates upon request.