It is my understanding that pressure derating for tapered thread (npt) pvc pipe/fitting connections is 50%. However, I know that FEMALE pvc threaded fittings are more susceptable to breakage (splitting). My question: would connecting a threaded sch 80 pvc nipple to a brass female fitting also involve a 50% derating? If so, I am assuming that this would be due to the reduction in wall thickness in the exposed threaded area(?).