In Plants, if we consider equipments such as pumps, heat exchanger, turbines etc. as human organs, pipes will be easily understood if we imagine them as the human blood vessels (artery and vein). Equipments are important but they alone would be meaningless. Only after connected by pipes are they able to play their roles.
Taking the pipelines around a turbine as an example, pipes are needed to send off steam from the boiler to the turbine. At the same time, pipes are also need to discharge excess steam and water.
Since various considerations are required to circulate different kinds of fluids, it is important to have a comprehensive viewpoint in Piping Design.
Work Flow
| Planning (1) | Plan the general route of piping based on the equipment layout drawing |
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| Planning (2) | Set piping specifications that will satisfy temperature and pressure conditions of the equipments |
| Standard Design | Perform stress analysis on the representative line and calculate the approximate quantity. |
| Detailed Design | Conduct stress analysis mainly on lines of high importance, and check the safety of the piping while considering the effect of the piping on the equipment and/or the structure. |
Of the above, our company is mainly in charge of the detailed design.
We shall explain further the procedures in detailed design.
Our main job is divided into three; Isometric drawing, Stress Analysis and Preparation of Calculation Sheets.
| What is Isometric Drawing? | It is a diagram that includes the the piping shape, specification, location of accessories (valve etc.) and positioning of the equipment nozzles for a better understanding of the whole layout. |
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| What is stress analysis? | Stress analysis consists of constructing the 3D model based on the Piping Drawing and the Isometric Drawing, applying the loading conditions and checking for safety. Loads include the thermal, earthquake, wind and vibration loads. |
We mainly use AutoPIPE and CAESAR II as analysis softwares.
Piping Seismic Diagnosis
In the recent years, aside from the aging of existing plants, earthquake countermeasures have become an urgent task. The need for Piping Seismic Diagnosis to evaluate the safety of pipes is increasing. In Piping Seismic Diagnosis, the actual system is modeled in 3D then, in addition to setting the conditions, one must perform analysis while considering various situations.
In analysis, we check whether there are defective parts or if the system is over-designed. If there is a part that exceeds the allowable value, we must plan the placing of the Piping Support (supports and restrains piping) or review the whole layout to resolve the problem.
Also, even if no error was observed, there may be an excessive reaction force locally therefore, analysis results must be checked thoroughly and calculated figures must be analyzed in detail.
Two contradicting factors must also be considered; Displacement due to earthquake (response displacement) and displacement due to internal shaking (inertia force). Designing the system that satisfies both factors will maintain the safety which is the main task of seismic diagnosis.
What to keep in mind in Piping Design
In piping design and piping seismic diagnosis, the contents(fluids) are highly flammable and toxic. For example, a piping system connected to a tank in which a large amount of hazardous materials are stored must be designed while considering various possibilities so as not to allow any leakage or damage.
High Pressure Gas Safety Law may be applied to different Pipings such as in Petroleum and Chemical Plants. The field of High Pressure Gas has a lot classifications under it which allows different fields to use its Laws and Regulations making it high in expertise thus very complicated. Unlike general piping, high-pressure gas piping requires performing seismic diagnosis assuming various situations.
In addition, it is important to arrange the schedule while keeping in contact with everyone from the early stages of the design. When remodeling high pressure gas piping, meeting the deadline is of utmost importance since construction can not be done unless there is examination from the municipality that controls the plant. Also, there are cases when the earthquake loads (other than the guidelines and notices) to be considered are determined specifically by each municipalities. Before making a diagnosis, this must be confirmed at the manufacturing facility or other departments concerned.
In Piping Design, to present a safe design means you are contributing to a lot of different people in the society. You may profit from it but in a different view, it is a very important job because a person's life is in your hands. As a person who performs piping design, hardwork must be encouraged so that legal understanding and comprehensive design could be done while keeping in mind a safe design.
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