The function of the strainer is to protect the valve or regulator from entraining dirt, scale or other solid substances carried in the process liquid, gas or vapor. Strainers are installed upstream from the valve or regulator to be protected at a minimum distance of 3'-0" of straight pipe. In hot vapor installations, upstream and downstream piping in the vicinity of the valve or regulator must be insulated to minimize condensation.
Steam traps are installed in steam lines to allow discharge of condensate and air while preventing loss of steam. The purpose of the steam trap is the discharge of condensate and non-condensable gases while preventing escape of live steam. The trap must be able to sense the difference and act accordingly. In the power plant, most traps remove condensate from steam lines. The condensate may be in large intermittent quantities, such as occur on start-up of a cold line or the quantities may be consistently large as for a constant heating or process load. A low, steady load can exist in a drain for a large insulated line that is shut off or carrying a light load. A trap must also discharge air and other non-condensable gases from the steam piping. This is a factor in trap design and selection