Strainers are important components of piping systems to protect equipment from potential damage due to dirt and other particles that may be carried by the process fluid.
During system start-up and flushing, Strainers may be placed upstream of pumps to protect them from construction debris that may have been left in the pipe. The figures here below depicts typical start-up Strainers. Permanent Strainers may be installed upstream of control valves, traps, and instruments to protect them from corrosion products that may become dislodged and carried throughout the piping system.
Centrifugal and reciprocating pumps handling material containing solids should have permanent Strainers provided in the suction lines to the pump or in the vessel from which the pump takes suction. The free area of such Strainers should be not less than three times the cross-sectional area of the suction line. The location of permanent Strainers (as contrasted to the temporary cone type which is installed at a flanged joint) also merits attention.