what is piperack and how to calculate piperack length

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

A piperack is a type of industrial structure that is commonly found in chemical and power plants, refineries, and other process industries. It serves as a support framework for various pipelines and process equipment that are interconnected throughout the facility.

The primary purpose of a piperack is to elevate and organize the network of pipes, conduits, and cables that transport fluids, gases, and electrical signals between different units or systems within the industrial plant. By lifting these components off the ground and arranging them systematically, it helps optimize space utilization and facilitates maintenance and inspection activities.

Piperacks are often made of  structural steel or concrete, depending on the facilfity’s specific needs. They are designed to withstand the weight of the pipes, support pipes and equipment they support, as well as environmental factors such as wind loads and seismic forces.

What point to be consider while designing piperack

  • Rack width
  • No of levels and elevations
  • Bent spacing, pipe flexibility
  • Access and maintenance of each item in the piperack.

How to calculate the width of Piperack

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.

Thumb rule for Pipe spacing to place the lines on pipe

Pipe Spacing (mm) = (Do + Dt) / 2 + 25mm + Thickness of Insulation (mm).

Where: D0 : OD of Small size Pipe (mm)

Dt : OD of Flange of Large size Pipe (mm)

Lines placement on the piperack

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 lines outside rack on cantilever beams or inside rack above top level, steam lines with expansion loops on one side of piperack, line s with orifice runs on one side of rack beside columns for maintenance using portable ladder.

In essence, a piperack is critical to the effective and safe functioning of industrial plants because it provides a sturdy and structured framework for the intricate network of pipes and equipment required for various operations. For piperack  information check here

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