Quality USA made NPT threaded Aluminum weld flanges stamped from 6061 flat sheet. Offered In sizes 1/8" NPT Through 2" NPT. Popular uses include fuel tanks, hydraulic tanks, Oil reservoirs and water tanks. NPT Fitting Sizes are based on the "PIPE" that would typically thread into these couplings. Use the Chart below to find the proper size match. It's important to understand that both the Male and Female NPT fitting have a 1.8 DEG taper applied to the thread. This taper is intended to create an interference fit once threaded together. It is expected that the male mating fitting will not thread all the way down. Sufficient tightness is created approx. 1 turn or less past hand tight, any further and you risk damaging the fitting. To get a liquid tight seal you will need to use thread sealant that is appropriate for your application We quality check every fitting with the appropriate size L1 thread gauge before entering our inventory. We do not replace fittings after they have been welded.