Reducing nipples, tapered male thread
Threaded fittings
Reducing nipples with a tapered male thread join two pipe sections of different size: the outside carries a tapered R thread, the inside a parallel Rp thread one or more steps smaller. The range covers 105 versions, male threads from R 1/8" to R 4", female threads from Rp 1/8" to Rp 3", rated up to 25 bar.
The tapered male thread seals in the thread flanks themselves, so no separate sealing face is needed on the mating part. Selection follows the two thread sizes, the pressure rating in addition to the material: cast stainless steel 1.4408, nickel plated brass as well as galvanised malleable iron, the latter covering the versions rated PN 25.
First determine the thread size of the port on the equipment, then the smaller size of the continuing line. A single step reduction such as R 1/2" to Rp 3/8" keeps the flow area high, whereas a large jump such as R 1" to Rp 3/8" creates a clear throttling effect. Match the material to the rest of the piping system so that no contact corrosion occurs at the joint.
Compressed air distribution in workshops as well as production halls, where ring mains in R 1" or R 2" step down to smaller branches feeding service units and tools. Also in pipework for water plus neutral fluids, when valves, pressure gauges and pumps carry a different thread size. Versions in 1.4408 serve chemical plants along with food processing lines, galvanised malleable iron serves systems rated 25 bar.
