pipe clamp fittings. Fittings are used to join and redirect pipes and components to form entire plumbing systems. Pipe fittings include things like pipe adapters, couplings, elbows, tees, sleeves, flanges, bulkhead fittings, reducers, and valves. Fittings are an important component of piping and plumbing systems that require money, time, materials, and tools to install. Pipe fittings are made separately and must be ordered separately.