Pentair FNS Plus Nylon Locknut

The Pentair FNS Plus Nylon Locknut (part number 58001000 or 58001000Z) is a precision-engineered structural fastening component designed exclusively for the heavy-duty external tension clamp assemblies of Pentair FNS Plus and select classic Titan series Diatomaceous Earth (D.E.) pool and spa filtration systems. Injection-molded from a high-tensile, glass-reinforced engineering nylon, this specialized hexagonal locknut features a localized polymer thread matrix designed to permanently bite into the main metal tension T-bolt. Its primary structural role is to serve as the main mechanical anchor that locks the split-ring metal tank clamp tightly around the overlapping flanges of the upper and lower tank shells. By maintaining continuous, uniform compressive tension on the main tank O-ring, this high-torque nut ensures the pressurized vessel can safely contain heavy hydraulic flow velocities and sustain internal system operating pressures up to 50 PSI without expanding, weeping at the mid-seam, or experiencing dangerous split-tank blowouts under intense pump vibration surges. Engineered to thrive in demanding outdoor mechanical pad environments, its reinforced nylon architecture completely resists thread-stripping, cross-threading, extreme seasonal thermal distortion, and corrosive exposure to splashed pool chemicals like concentrated chlorine, bromine, and winterizing acid washes. Due to its dense but ultra-compact polymer nut geometry, this individual hardware component is exceptionally lightweight, carrying a nominal product and shipping weight of approximately 0.01 pounds (about 0.16 ounces).