Anderson Metals brass locknut with female pipe thread (NPT/FPT). A locknut threads onto a male NPT nipple or bulkhead fitting and tightens from the back side to clamp the fitting in place against a tank wall, panel, sink deck, junction box, or electrical service entrance. Solid brass body resists corrosion in damp service and won't rust like a steel locknut would.

• Material: Solid brass
• Thread: NPT (FPT - female pipe thread)
• Corrosion resistant - won't rust in damp service like steel
• Wrench-flat hex shape - tighten with a standard adjustable or open-end wrench
• Pairs with matched NPT male nipple, bulkhead fitting, or thru-panel valve stem
• Size: 1/2" FPT

Selection Tip: Match the locknut size exactly to the male NPT thread being anchored. A 1/2" locknut fits a 1/2" NPT nipple (real OD around 0.84"); a 3/4" locknut fits a 3/4" NPT nipple. Mixing sizes cross-threads brass and cracks the locknut. For service that will see hot water above 200 deg F or pressure above the low-to-medium range, step up to a forged brass or stainless locknut sized for the duty.

Application Tip: Use two wrenches when tightening - one on the locknut, one on the fitting being anchored - so the fitting doesn't spin in the bulkhead while you torque the locknut. Bed a washer or gasket between the locknut and the panel surface for tanks, troughs, or any wet-service penetration to prevent weeping at the threads. Wrap the male NPT thread with 2-3 turns of PTFE tape before final assembly.

Note: This is a low-to-medium pressure plumbing and pneumatic fitting. For potable water service, verify the part meets the lead-content rule that applies in your jurisdiction; for natural gas or LP service, verify the part is approved for fuel-gas duty by your local code.