A pipe rack refers to a structure that is designed and installed specifically to support multiple pipes in a place where an adequate building or structure is not available. It is mainly designed outside the building. 

Pipe racks are utilised for arranging the process and utility pipelines all over the plant. It connects all the equipment (installed at different locations) with lines that can not be placed in an adjacent line. A pipe rack is considered the best means to group and route plant piping in an organised manner. 

Pipe racks are not just used to support multiple pipes, but they can also be used in other ways, such as carrying electrical wire, instrument wire, fire fighting systems, lights, etc. You might notice that air-cooled or fin-fan type heat exchangers are often supported above pipe racks to reduce the plant space requirements. 

Types of Pipe Rack

Generally, there are three types of Pipe racks:

• Steel Structure Type
• RCC Structure Type
• Sleeper Type (This is also called Pipe Track)

Design and Development of Pipe rack

Every plant has its requirement for pipe racks, so every plant will have a unique pipe rack layout design to comply with the plant’s requirements. 

While creating a pipe rack layout design, there are multiple things that one needs to consider, such as the configuration and size of the pipe rack. It is established based on the overall plot plan arrangement, process requirement, and plant economy. 

In the early stage of plant layout development, specifically at the conceptual stage (when things are put in theory and planned out), the main pipe racks must be sized to establish their overall footprint and elevations. The height and number of pipe rack levels should be established. The location and approximate size of the instrument and electrical trays should be established as well. As we progress toward a detailed development process and as more information becomes available, we can finalise a detailed rack layout. It includes:

• Finalizing the dimensions of the pipe rack
• Finalizing the spacing of pipes on the rack
• Finalizing the rack column spacing
• Expansion loop requirements
• Location of Anchor bays

A pipe rack structural drawing requires a considerable amount of planning and coordination with all disciplines to ensure that all the relevant requirements are taken into consideration, including the constructability aspects and any impact on the adjacent process units.

Piping Study

At the initial stage of plot development, a piping study is conducted to identify the various lines routed on the pipe rack. The piping study is conducted to find out the estimated pipe rack width and elevations and pipe rack runs required in various areas of the plant. Now, to proceed further with the piping study, the following inputs are required:

• Process and Instrumentation Diagrams.

• We need a line list. This list should indicate the line sizes, operating and design conditions, and insulation requirements. It might include any other specific process requirements such as lines with no pockets, lines requiring slope, orifice meter runs, etc.

• Based on the line list, we should identify the stress critical lines and a preliminary stress analysis must be carried out to identify the requirements of expansion loops and anchor bays.

• The pipe racks with hydrocarbons in them may require fire-proofing of structural members to ensure there is no risk to the critical structural elements.

While designing a pipe rack design, sufficient space should be provided for future expansions. The space for future expansion may vary from 15-30% depending on the requirements of the owner. The space for future expansion may determine the overall pipe rack width. It may become important to create a provision of another tier on the pipe rack if the future space requirements cannot accommodate within the pipe rack width.

We know that the pipe rack is located in the middle of the process units, so it must be erected before the erection of the adjacent process units. So, the load inputs and dimensions of the rack design to the structural department become important. It becomes one of the early requirements during the detailed design phase.

If you are inclined towards piping design and drafting, then there are a lot of piping design and drafting courses both online and offline. You could enroll yourself in any of the drafting courses and get yourself started with piping design. If you are not sure about a career in piping design and drafting, then there are a lot of videos and articles available over the net. Make use of your resources, do detailed research, and make your decision.