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LESSONS & TOPICS

Data Preparation

Data Preparation

So you have been assigned the responsibility to perform Stress Analysis for one of the piping system. So, followings are the things that you should do in order to make you ready forthe job, starting with below:

I. CALCULATION NUMBER

Lead Stress Engineer normally have prepared the list of calculation numbering format earlier in the project, under the document call as Piping Stress Analysis Guideline, or could be any other name, but with same idea whcih one othem consist of Calculation Numbering Format. This format normally least has: area number, sequence number, and revision number, while some company would have also project name.
 

The purpose of this calculation format and numbering is to put a good record of how many calculation for specific project as well as tracking which engineer performing the analysis. This is also good way to record any revision due to change in design parameter or design in piping layout.

 

II. STRESS SKETCH

Now we get the calculation number for the lines that we will perform the analysis. The next step is to get the blank form of Stress Isometric Sketch and ready to start the stress sketch. But, before you start sketching your pencil into the paper, we’d better to have several documents and do some preliminary hand-calculation to make the process of making piping stress sketch even smoother, as folowings:

 
1. PIPING SPECIFICATION
Piping Stress Analysis Specification, Pipe Support Drawings and Specification are the documents that you should have in your table once you are part of the Stress Team. You may also need to have copy of ASME B31.3 Codes in your computer and some other piping standards which will be handy when you need to know the Thermal Coefficient for specific material at temperature to calculate Nozzle Initial Movement, for example.
 
2. PIPING DATA
This document shows pipe data such as pipe outside diameter, wall thickness or schedule, pipe weight per meter, dimension, as well as the information about fittings, flanges, bolts, nuts, valves, which will be very useful and needed for completing the stress sketch prior to input into CAESAR II computer program. The information needed such as the dimension and weight, and etc.
 
3. PIPING DRAWINGS
Piping General Ararangement and Piping Isometric are the next documents or drawing you should have in order to start the making of piping stress sketch. Some company normally use Piping Isometric as Piping Stress Isometric, by just adding nodes point for each of location required as well as putting the type of pipe support. It’s ok if you just have short piping on the system, but it becoming not really nice when you have long line and branching everywhere and you could end up having 10 pages of isometric. Therefore, it’s better to draw it by your self.
 
4. PROCESS DATA
Next on the list is Process line list, which contains the design data of the system that you are going to analyse such as type of liquid, Design Pressure, Test medium, Maximum Design temperature, Minimum Temperature, Operating Temperature, Steam Out Temperature if any, one phase or two phase flow, any possibility of surge, etc.
 
5. EQUIPMENT DRAWINGS
This is very important to have at the early stage of project. You will need it to get the information of what the Equipment looks like, the design data, operating temperature, and Allowable Forces and Moments. With this documents, you can start calculate the Nozzle Initial Movement as well as pipe support movement if attached to the equipment such as Vertical Vessel or Column.
 
You may calculate the nozzle initial movement for every single nozzle using its Operating Temperature and make a note for each nozzle. So next time, when you come to the calculation for that nozzle, it will save your time to calculate the Initial Movement, as shown on sample image below.
 
6. SPRING HANGER CATALOGUE
Catalogue of Spring Hanger Support may also good to have in case your lines need to have those kind of devices in particular for the lines connected to sensitive equipment such as Compressors, Turbine, or even to Centrifugal Pumps. You may need to understand how it works and how to apply it into your calculation.