LINE SIZING VELOCITY CRITERIA

LINE SIZING CRITERIA FOR LIQUID( HYDROCARBON AND OTHER ORGANIC LIQUIDS) LINES( carbon steel):In the Pump suction line sizing the safe velocity is 0.3-0.9 m/sec.for non boiling liquids and 0.3-0.6 m/sec for boiling liquid.
pump dischrge side line sizing velocity 1.2-2.7 m/sec. if the discharge side line is short length, for long length velocity criteria is 0.6-0.9 m/sec.

LIQUID FROM CONDENSER : 0.9-1.8 m/s          
REFRIGERATION LINE    : 0.6-1.2 m/s
GRAVITY FLOW LINE     : 0.9-2.5 m/s
REBOILER INLET        : 0.3-1.2 m/s
LIQUID FEED TO TOWER  : 1.2-1.8 m/s

WATER                                
General service      :0.6-1.5 m/s     
Pump discharge        :0.6-4.9 m/s
Boiler feed           :2.5-4.5 m/s
Cooling water         :3.6-4.8 m/s
caustic solution      :1.2-1.6 m/s
Viscous Oil
Pump suction :0.2 m/s
Pump discharge :0.3-0.9m/s

For reference for above writeup follow the link :

http://books.google.co.in/books?id=LlBbRckWAeQC&lpg=PA137&ots=x4yEU5vZBB&dq=line%20sizing%20criteria&pg=PA136#v=onepage&q=line%20sizing%20criteria&f=false