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Piping Layout-Purpose and General Rules

A Refinery 
Even though it is one of the most important aspects of Piping Design, There is no established code exists for Piping Layout. Piping Layout is all about the arrangement of Piping. Layout Preparation doesn’t deal with the ability of the piping system to handle fluid under given design condition, rather deals with the efficient and safe operation of the plant.


A talented Piping Layout Engineer should possess good craftsmanship with great personal skills, creative imaginations etc. In preparing a good Layout. Depending upon the particular situation, the piping arrangement will vary from case to case. To ensure a well laid out piping, a logical approach is necessary with an intelligent and careful study by the Piping Engineer.Piping Plans are usually made area wise.

Piping Plans:
A piping Plan is usually made in 1:33 1/3 scale for process units, 1:50 scale for pipe racks and validity units and 1:100 for Storage Tank Area. Generally, Piping Plans will be with floor wise plans and local sectional views are given as required.
Normally, a piping plan is prepared in two stages. In the first stage, it is called as a study Piping Plan. The piping study plan is basically a conceptual proposal consisting of pipe routings in plans and sections of all pipe sections of all pipelines. (2” NB and above) fulfilling all conditions laid down in P & ID s and identifying schematically locations of all control stations, rotameter stations, valves, inline-instruments, etc. The Piping study plan should necessarily show all platform sizes, locations, and elevations required for operations and maintenance of piping/instrument components. Lines less than 50 NB are generally not shown. However, depending on the criticality and extent of small sized lines in a particular unit line less than 50 NB may be required be shown. Usually, the study plan starts with laying of the critical lines first-Critical lines are those with either a Large diameter or having a high temperature or gravity lines.

The study piping plans along with ISO sketches are discussed with other departments in order to get their comments at the conceptual stage. Technically Speaking, there is no difference between a study piping plan and a final piping plan except a study piping is minus beautification/cosmetic look. While the main purpose of a study piping plan is obtaining approval on conceptual routing from inter departments as early as possible without spending much time on beautification of drawings.

Also, a few more Purposes are listed below.


1.     Freeze the equipment locations after piping study by
satisfying all requirements as far as possible.

2.     Finalize the Nozzle orientation and cleats for platforms & Ladders associated with the equipment.

3.     Feed data to stress group for thermal analysis of the lines.

4.     Furnish top of foundation elevations & other related data

5.     Furnish information to the modelling group for preparation of a scaled model where applicable.

6.     Preparation of Bill of Material for ordering Pipes & Fittings


7.     Other department references such as Instrumentation and electrical for finalization of their cable routings. Study piping Plans are usually updated after getting comments from other departments, as well as from stress group and also the review of the model by licensor/Client at different stages.

3D Piping Plan View

 Following Guidelines are very important for any good Piping Plan:
1.     All the Process Requirements as per P& ID demand should be met.
2.     Lines should be arranged in an orderly and neat manner with the proper grouping of lines or banks wherever it is practically possible to achieve.
3.     As far as possible the line routing should permit the use of Standard Pipe Fittings as per Pipe Spec.
4.     Routing should be made such that, it will be easy to support from available    structure 
5.     Piping should not be located at grade, especially at areas where frequent traffic is likely. This is important when         choice is to be made between sleepers and pipe rack
6.     Piping should not block material handling. Crane, hoists etc should be easy to operate
7.     Inline components which need regular maintenance should be easy to access
8.     Clear working space should be there around equipment demands the same.
9.     All Valves should be easily accessible from grade or from permanent platforms
10. Adequate arrangement for platforms and ladders for column manways
11. Removal of equipment for maintenance if any, should cause minimum dismantling to the Pipe.
12. Pocket formation should be avoided, especially in relief lines
13. Hotlines and condensate lines should be away from electrical conduits
14. Flexibility of Hotlines should be provided



       


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