What is 150 LB threaded pipe fittings ? 150 LB threaded pipe fittings are the parts that connect the pipe into a pipeline. According to the connection method, threaded fittings can be divided into four categories: socket pipe fittings, threaded pipe fittings, flange pipe fittings and welded pipe fittings. It is mostly made of the same material as the tube. There are elbows (elbow tubes), tee tubes, four-way tubes (cross heads) and reducers (large and small heads). Elbows are used where the tube turns; Tee tubes are used where three tubes converge; Four-way tubes are used where four tubes converge; Reducers are used where two tubes of different diameters are connected. Get more custom pipe fittings from HY Valve.