Valve Usage, Typical Applications

The following are some general applications where valves are used to accomplish system design objectives :
a. To start and stop fluid flow as required by the process, e.g., sluice water flow for bottom ash conveying;
b. To modulate fluid flow as required by the process, e.g., deaerator storage tank level control;
c. To balance the flow between a number of parallel flow paths, e.g., cooling water disharge from lube oil coolers;
d. To fill and/or vent the system during startup, e.g., boiler filing valves or high point vents;
e. To drain the system after shutdown or to carry out repairs, e.g., equipment drain valves;
f. To prevent overpressure and potential failure of equipment, e.g., safety valves (A subject of another Rekayasa Industri Design Guide);
g. To isolate equipment or control valves for repair or maintenance, e.g., block valves upstream and downstream of a heater and a by-pass valve;
h. To reduce consequences of pipe breaks (i.e., insurance against an unexpected but possible event), e.g., isolation valves at branch lines or sectionalizing valve in a fire water loop;
i. Provisions for future additions, e.g., valves at connection points for future additions;
j. Instrument isolation. E.g., instrument root valves;
k. Connections for purging the equipment prior to repairs, e.g., such as steam-in and steam-out valved connections.