what is piperacks designing

In Pipe rack we are putting bunch of piping and electrical and instruments cable trays. Pipe rack is used to connect the pipes from one end to another end of the plant.  Rack saves a lots of plant design cost. Pipe rack may be two tiers, three tiers or may be single tier as per the requirement of the plant. 

While designing pipe rack following considerations have to take care:-
  • Rack width,
  • No of levels and elevations,
  • Bent spacing, pipe flexibility,
  • Access and maintenance of each item in the pipe rack.
Calculate the width of Pipe rack
w= (f X n X s) + A + B.      
f : Safety Factor
  • 1.5 if pipes are counted from PFD.
  • 1.2 if pipes are counted from P&ID.
n = number of lines in the densest area up to size 450NB.
  • 300 mm (Estimated average spacing)
  • 225 mm (if lines are smaller than 250 NB)
A : Additional Width for
  • Lines larger than 450 NB.
  • For instrument cable tray
  • For Electrical cable tray. 
s : 300 mm (estimated average spacing)
     225 mm (if lines are smaller than 250 NB)
B : future provision
  • 20% of (f X n X s) + A
The pipe Rack width is limited to 6.00 Mtrs. If the width of rack calculated is more then the arrangement shall be done in multiple layers. Normally, 5 to 6 Mtrs. spacing is kept in between the column of pipe rack.

The arrangements adopted are: -
  • Single column Rack ‘T’ type.
  • Double column Rack with a single tier.
  • Double column Rack with a double tier.
Lines placement on the pipe rack
Process lines on lower level, utility lines on top level, instrument and cable trays on utility level or separate topmost level, Heavy lines near columns, Flare line outside rack on cantilever beams or inside rack above top level, steam lines with expansion loops on one side of pipe rack, line s with orifice runs on one side of rack beside columns for maintenance using portable ladder.

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