Skip to main content

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



       


Comments

Post a Comment

Most Popular

Wall Thickness Calculation of Pipes

Nominal Wall Thickness Calculation Of metallic pipes needs the following information as a Pre-requisite. a) Design Pressure, b) Design Temperature, c) Material Specification, d) Pipe Size e) Applicable Code As Per B 31.3, the required thickness of a Straight Section of Pipe is given by the relation t m =t+c Where , t m =Minimum thickness required including, mechanical corrosion and erosion allowance t=Thickness Required to withstand internal pressure c=Sum of Mechanical Allowance (thread, groove depth) added with corrosion and erosion allowance. Let's Go through each term in the above equation i) Thickness Required to withstand internal pressure [ t ] Nominal wall thickness should be Greater than or equal to the sum of the minimum required thickness and Manufacturer’s Negative tolerance. As per the Code Minimum Thickness t =PD/2(SE+PY) Here, P=Design Pressure (Gauge) D=Outside Diameter of Pipe S=Allowable Stress...
Post a Comment
Read more

Piping Specification-details and the preparation process

Piping Specifications are usually in the form of a manual containing the below-listed points, but not limited to             1 )       Pipe Class and Specifications.             2)       Pipe and fittings thickness table for the different class of piping.             3)       P & ID Abbreviations and Symbols.             4)       List of fluids with Design conditions and Pipe Class.             5)       List of Valves and Gaskets.             6)       Table of Branch connections for different Pipe Classes.             7)       Table of Bolt length.         ...
Post a Comment
Read more

Details of Sustained and Displacement Stresses-Core of Pipe Stress Analysis

Piping flexibility analysis as per B31.3code requirements is dealing with two types of stress named as Sustained Stress and Displacement stress .  Both types of stress must be considered separately because sustained stresses are associated with sustained forces while displacement stresses are associated with fixed displacements. SUSTAINED STRESSES: Sustained Stresses are stresses caused by loads that are not relieved as the piping system deflects. See the diagrammatic representation below to get an idea about this.  The weight of the valve placed at the end of the cantilevered pipe induce Stress at the T-Joint. Regardless of the magnitude of the displacement (∆), the magnitude of the load (the weight of the valve) which causes the stress is unchanged.  Therefore, to avoid catastrophic failure, the magnitude of any sustained stress must not exceed the yield strength of the material.  Another example of a sustained stress is the hoop and longitudinal stres...
Post a Comment
Read more