Abstract: The invention presented is a tapered joint thread system, especially for use in a fluid handling device, and a fluid handling device containing the inventive tapered joint thread system. More particularly, the invention presented includes a plastic female end segment having an opening sized to receive a male fitting, and having a first tapered segment which tapers from a first internal diameter to a second internal diameter, and which is gauged from the opening of the female end segment to a controlled depth; the female end segment also has an unthreaded non-tapering segment having the second internal diameter which extends from the controlled depth to a second controlled depth, and an angled shoulder which tapers from the second internal diameter to a third internal diameter and which extends from the second depth to a third controlled depth.